ovs-ofctl(8)

💖 NAME 💖

ovs-ofctl — administer OpenFlow switches. This is the ovs-ofctl(8) page from the Open vSwitch Manual, and bestie, we are going to get through it together. 💅

🦋 SYNOPSIS 🦋

ovs-ofctl [options] command [switch] [args...]

✨ DESCRIPTION ✨

Okay so ovs-ofctl is a command line tool for monitoring and administering OpenFlow switches. It can also show the current state of an OpenFlow switch, including features, configuration, and table entries. And the iconic part? It should work with any OpenFlow switch, not just Open vSwitch. 🫶

🌈 OpenFlow Switch Management Commands 🌈

These commands let ovs-ofctl monitor and administer an OpenFlow switch. It is able to show the current state of a switch, including features, configuration, and table entries. ✨

Most of these commands take an argument that specifies the method for connecting to an OpenFlow switch. The following connection methods are supported:

• ssl:host[:port], tcp:host[:port] — The specified port on the given host, which can be expressed either as a DNS name (if built with unbound library) or an IP address in IPv4 or IPv6 address format. Wrap IPv6 addresses in square brackets, e.g. tcp:[::1]:6653. On Linux, use %device to designate a scope for IPv6 link-level addresses, e.g. tcp:[fe80::1234%eth0]:6653. For ssl, the --private-key, --certificate, and --ca-cert options are mandatory. If port is not specified, it defaults to 6653.
• unix:file — On POSIX, a Unix domain server socket named file.
• file — This is short for unix:file, as long as file does not contain a colon.
• bridge — This is short for unix:/run/openvswitch/bridge.mgmt, as long as bridge does not contain a colon.
• [type@]dp — Attempts to look up the bridge associated with dp and open as above. If type is given, it specifies the datapath provider of dp, otherwise the default provider system is assumed.

🎀 show switch 🎀

Prints to the console information on switch, including information on its flow tables and ports. Show me everything, king. 👑

🎀 dump-tables switch 🎀

Prints to the console statistics for each of the flow tables used by switch.

🎀 dump-table-features switch 🎀

Prints to the console features for each of the flow tables used by switch.

🎀 dump-table-desc switch 🎀

Prints to the console configuration for each of the flow tables used by switch for OpenFlow 1.4+.

🎀 mod-table switch table setting 🎀

This command configures flow table settings in switch for OpenFlow table table, which may be expressed as a number or (unless --no-names is specified) a name.

The available settings depend on the OpenFlow version in use. In OpenFlow 1.1 and 1.2 (which must be enabled with the -O option) only, mod-table configures behavior when no flow is found when a packet is looked up in a flow table. The following setting values are available:

• drop — Drop the packet.
• continue — Continue to the next table in the pipeline. (This is how an OpenFlow 1.0 switch always handles packets that do not match any flow, in tables other than the last one.)
• controller — Send to controller. (This is how an OpenFlow 1.0 switch always handles packets that do not match any flow in the last table.)

In OpenFlow 1.3 and later (which must be enabled with the -O option) and Open vSwitch 2.11 and later only, mod-table can change the name of a table:

• name:new-name — Changes the name of the table to new-name. Use an empty new-name to clear the name. (This will be ineffective if the name is set via the name column in the Flow_Table table in the Open_vSwitch database as described in ovs-vswitchd.conf.db(5).)

In OpenFlow 1.4 and later (which must be enabled with the -O option) only, mod-table configures the behavior when a controller attempts to add a flow to a flow table that is full. The following setting values are available:

• evict — Delete some existing flow from the flow table, according to the algorithm described for the Flow_Table table in ovs-vswitchd.conf.db(5).
• noevict — Refuse to add the new flow. (Eviction might still be enabled through the overflow_policy column in the Flow_Table table documented in ovs-vswitchd.conf.db(5).)
• vacancy:low,high — Enables sending vacancy events to controllers using TABLE_STATUS messages, based on percentage thresholds low and high.
• novacancy — Disables vacancy events.

🎀 dump-ports switch [netdev] 🎀

Prints to the console statistics for network devices associated with switch. If netdev is specified, only the statistics associated with that device will be printed. netdev can be an OpenFlow assigned port number or device name, e.g. eth0.

🎀 dump-ports-desc switch [port] 🎀

Prints to the console detailed information about network devices associated with switch. To dump only a specific port, specify its number as port. Otherwise, if port is omitted, or if it is specified as ANY, then all ports are printed. This is a subset of the information provided by the show command.

If the connection to switch negotiates OpenFlow 1.0, 1.2, or 1.2, this command uses an OpenFlow extension only implemented in Open vSwitch (version 1.7 and later).

Only OpenFlow 1.5 and later support dumping a specific port. Earlier versions of OpenFlow always dump all ports.

🎀 mod-port switch port action 🎀

Modify characteristics of port port in switch. port may be an OpenFlow port number or name (unless --no-names is specified) or the keyword LOCAL (the preferred way to refer to the OpenFlow local port). The action may be any one of the following:

• up, down — Enable or disable the interface. This is equivalent to ip link set up or ip link set down on a Unix system.
• stp, no-stp — Enable or disable 802.1D spanning tree protocol (STP) on the interface. OpenFlow implementations that don't support STP will refuse to enable it.
• receive, no-receive, receive-stp, no-receive-stp — Enable or disable OpenFlow processing of packets received on this interface. When packet processing is disabled, packets will be dropped instead of being processed through the OpenFlow table. The receive or no-receive setting applies to all packets except 802.1D spanning tree packets, which are separately controlled by receive-stp or no-receive-stp.
• forward, no-forward — Allow or disallow forwarding of traffic to this interface. By default, forwarding is enabled.
• flood, no-flood — Controls whether an OpenFlow flood action will send traffic out this interface. By default, flooding is enabled. Disabling flooding is primarily useful to prevent loops when a spanning tree protocol is not in use.
• packet-in, no-packet-in — Controls whether packets received on this interface that do not match a flow table entry generate a “packet in” message to the OpenFlow controller. By default, “packet in” messages are enabled.

The show command displays (among other information) the configuration that mod-port changes.

🎀 get-frags switch 🎀

Prints switch's fragment handling mode. See set-frags, below, for a description of each fragment handling mode.

The show command also prints the fragment handling mode among its other output.

🎀 set-frags switch frag_mode 🎀

Configures switch's treatment of IPv4 and IPv6 fragments. The choices for frag_mode are:

• normal — Fragments pass through the flow table like non-fragmented packets. The TCP ports, UDP ports, and ICMP type and code fields are always set to 0, even for fragments where that information would otherwise be available (fragments with offset 0). This is the default fragment handling mode for an OpenFlow switch.
• drop — Fragments are dropped without passing through the flow table.
• reassemble — The switch reassembles fragments into full IP packets before passing them through the flow table. Open vSwitch does not implement this fragment handling mode.
• nx-match — Fragments pass through the flow table like non-fragmented packets. The TCP ports, UDP ports, and ICMP type and code fields are available for matching for fragments with offset 0, and set to 0 in fragments with nonzero offset. This mode is a Nicira extension.

See the description of ip_frag, in ovs-fields(7), for a way to match on whether a packet is a fragment and on its fragment offset.

🎀 dump-flows switch [flows] 🎀

Prints to the console all flow entries in switch's tables that match flows. If flows is omitted, all flows in the switch are retrieved. See Flow Syntax, below, for the syntax of flows. The output format is described in Table Entry Output.

By default, ovs-ofctl prints flow entries in the same order that the switch sends them, which is unlikely to be intuitive or consistent. Use --sort and --rsort to control display order. The --names/--no-names and --stats/--no-stats options also affect output formatting. See the descriptions of these options, under OPTIONS below, for more information.

🎀 dump-aggregate switch [flows] 🎀

Prints to the console aggregate statistics for flows in switch's tables that match flows. If flows is omitted, the statistics are aggregated across all flows in the switch's flow tables. See Flow Syntax, below, for the syntax of flows. The output format is described in Table Entry Output.

• queue-stats switch [port [queue]] — okay so this prints to the console the stats for the specified queue on port inside switch. port can be an OpenFlow port number or name, the keyword LOCAL (the preferred way to refer to the OpenFlow local port), or the keyword ALL. Either port or queue or both may be omitted, or equivalently you can use the keyword ALL. If both are omitted, stats are printed for all queues on all ports. If only queue is omitted, then stats are printed for all queues on port; if only port is omitted, then stats are printed for queue on every port where it exists. slay.
• queue-get-config switch [port [queue]] — prints to the console the configuration of queue on port in switch. If port is omitted or ANY, it reports queues for all ports. If queue is omitted or ANY, it reports all queues. For OpenFlow 1.3 and earlier, the output always includes all queues, ignoring queue if specified. ngl, this command has limited usefulness, because ports often have no configured queues and because the OpenFlow protocol provides only very limited information about the configuration of a queue.
• dump-ipfix-bridge switch — prints to the console the statistics of bridge IPFIX for switch. If bridge IPFIX is configured on the switch, IPFIX statistics can be retrieved. Otherwise, an error message will be printed. This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later. iykyk.
• dump-ipfix-flow switch — prints to the console the statistics of flow-based IPFIX for switch. If flow-based IPFIX is configured on the switch, statistics of all the collector set ids on the switch will be printed. Otherwise, it prints an error message. Refer to ovs-vswitchd.conf.db(5) for more details on configuring flow based IPFIX and collector set ids. This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later. obsessed with a good collector set id.
• ct-flush-zone switch zone — flushes the connection tracking entries in zone on switch. This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later.
• ct-flush switch [zone=N] [mark=X[/M]] [labels=Y[/N]] [ct-orig-tuple [ct-reply-tuple]] — flushes the connection entries on switch based on zone, mark, labels and connection tracking tuples ct-[orig|reply]-tuple.

If ct-[orig|reply]-tuple is not provided, this flushes all the connection entries. If zone is specified, it only flushes the connections in zone. If mark or labels is provided, it will flush only entries that are matching the specific mark/labels. If ct-[orig|reply]-tuple is provided, it flushes the connection entry specified by ct-[orig|reply]-tuple in zone. The zone defaults to 0 if it is not provided. The mark and labels default to "0/0" if they are not provided. The userspace connection tracker requires flushing with the original pre-NATed tuple, and a warning log will be otherwise generated. The tuple can be partial and will remove all connections that are matching on the specified fields. In order to specify only ct-reply-tuple, provide an empty string as ct-orig-tuple.

Note: Currently there is limitation for matching on ICMP. In order to partially match on ICMP parameters, the ct-[orig|reply]-tuple has to include either source or destination IP.

An example of an IPv4 ICMP ct-[orig|reply]-tuple:

"ct_nw_src=10.1.1.1,ct_nw_dst=10.1.1.2,ct_nw_proto=1,icmp_type=8,icmp_code=0,icmp_id=10"

An example of an IPv6 TCP ct-[orig|reply]-tuple:

"ct_ipv6_src=fc00::1,ct_ipv6_dst=fc00::2,ct_nw_proto=6,ct_tp_src=1,ct_tp_dst=2"

This command uses an Open vSwitch extension that is only in Open vSwitch 3.1 and later. Support for matching on mark and labels is only in Open vSwitch 3.3 and later. the way this one has lore is unreal 💅

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🔥 OpenFlow Switch Flow Table Commands 🔥

These commands manage the flow table in an OpenFlow switch. In each case, flow specifies a flow entry in the format described in Flow Syntax, below; file is a text file that contains zero or more flows in the same syntax, one per line; and the optional --bundle option operates the command as a single atomic transaction, see option --bundle, below. bestie, atomic transaction is giving main character energy.

• [--bundle] add-flow switch flow [--bundle] add-flow switch - < file [--bundle] add-flows switch file — add each flow entry to switch's tables. Each flow specification (e.g., each line in file) may start with add, modify, delete, modify_strict, or delete_strict keyword to specify whether a flow is to be added, modified, or deleted, and whether the modify or delete is strict or not. For backwards compatibility, a flow specification without one of these keywords is treated as a flow add. All flow mods are executed in the order specified.
• [--bundle] [--strict] mod-flows switch flow [--bundle] [--strict] mod-flows switch - < file — modify the actions in entries from switch's tables that match the specified flows. With --strict, wildcards are not treated as active for matching purposes.
• [--bundle] del-flows switch [--bundle] [--strict] del-flows switch [flow] [--bundle] [--strict] del-flows switch - < file — deletes entries from switch's flow table. With only a switch argument, deletes all flows. Otherwise, deletes flow entries that match the specified flows. With --strict, wildcards are not treated as active for matching purposes.
• [--bundle] [--readd] replace-flows switch file — reads flow entries from file (or stdin if file is -) and queries the flow table from switch. Then it fixes up any differences, adding flows from file that are missing on switch, deleting flows from switch that are not in file, and updating flows in switch whose actions, cookie, or timeouts differ in file.

With --readd, ovs-ofctl adds all the flows from file, even those that exist with the same actions, cookie, and timeout in switch. In OpenFlow 1.0 and 1.1, re-adding a flow always resets the flow's packet and byte counters to 0, and in OpenFlow 1.2 and later, it does so only if the reset_counts flag is set. no cap, counters are precious.

• diff-flows source1 source2 — reads flow entries from source1 and source2 and prints the differences. A flow that is in source1 but not in source2 is printed preceded by a -, and a flow that is in source2 but not in source1 is printed preceded by a +. If a flow exists in both source1 and source2 with different actions, cookie, or timeouts, then both versions are printed preceded by - and +, respectively.

source1 and source2 may each name a file or a switch. If a name begins with / or ., then it is considered to be a file name. A name that contains : is considered to be a switch. Otherwise, it is a file if a file by that name exists, a switch if not.

For this command, an exit status of 0 means that no differences were found, 1 means that an error occurred, and 2 means that some differences were found. exit codes ate, fr fr.

• packet-out switch packet-out — connects to switch and instructs it to execute the packet-out OpenFlow message, specified as defined in Packet-Out Syntax section.

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🫶 Group Table Commands 🫶

These commands manage the group table in an OpenFlow switch. In each case, group specifies a group entry in the format described in Group Syntax, below; file is a text file that contains zero or more groups in the same syntax, one per line; and the optional --bundle option operates the command as a single atomic transaction, see option --bundle, below.

The group commands work only with switches that support OpenFlow 1.1 or later or the Open vSwitch group extensions to OpenFlow 1.0 (added in Open vSwitch 2.9.90). For OpenFlow 1.1 or later, it is necessary to explicitly enable these protocol versions in ovs-ofctl (using -O). For more information, see Q: What versions of OpenFlow does Open vSwitch support? in the Open vSwitch FAQ. lowkey a whole vibe check for protocol versions.

• [--bundle] add-group switch group [--bundle] add-group switch - < file [--bundle] add-groups switch file — add each group entry to switch's tables. Each group specification (e.g., each line in file) may start with add, modify, add_or_mod, delete, insert_bucket, or remove_bucket keyword to specify whether a flow is to be added, modified, or deleted, or whether a group bucket is to be added or removed. For backwards compatibility, a group specification without one of these keywords is treated as a group add. All group mods are executed in the order specified.
• [--bundle] [--may-create] mod-group switch group [--bundle] [--may-create] mod-group switch - < file — modify the action buckets in entries from switch's tables for each group entry. If a specified group does not already exist, then without --may-create, this command has no effect; with --may-create, it creates a new group. The --may-create option uses an Open vSwitch extension to OpenFlow only implemented in Open vSwitch 2.6 and later.
• [--bundle] del-groups switch [--bundle] del-groups switch [group] [--bundle] del-groups switch - < file — deletes entries from switch's group table. With only a switch argument, deletes all groups. Otherwise, deletes the group for each group entry.
• [--bundle] insert-buckets switch group [--bundle] insert-buckets switch - < file — add buckets to an existing group present in the switch's group table. If no command_bucket_id is present in the group specification, then all buckets of the group are removed. not me reading that twice, but okay periodt.
• [--bundle] remove-buckets switch group [--bundle] remove-buckets switch - < file — remove buckets to an existing group present in the switch's group table. If no command_bucket_id is present in the group specification, then all buckets of the group are removed.
• dump-groups switch [group] — prints group entries in switch's tables to console. To dump only a specific group, specify its number as group. Otherwise, if group is omitted, or if it is specified as ALL, then all groups are printed. Only OpenFlow 1.5 and later support dumping a specific group. Earlier versions of OpenFlow always dump all groups.
• dump-group-features switch — prints to the console the group features of the switch. iconic little info dump.
• dump-group-stats switch [group] — drops the console stats for the group you named in switch's tables. Skip the group arg and it just prints stats for, like, every group it's got. 💅

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🎀 OpenFlow 1.3+ Switch Meter Table Commands 🎀

okay so these commands are all about managing the meter table inside an OpenFlow switch. In every single one of these, meter means a meter entry written in the format described down in Meter Syntax, below — go look, it's there, bestie. 🌸

Real talk though: meters are an OpenFlow 1.3 thing, so these commands only work with switches that actually support OpenFlow 1.3 or later. Like, you have to explicitly enable those protocol versions — both in ovs-ofctl (that's the -O option, mwah) and in the switch itself (that's the protocols column in the Bridge table). For the whole story, peep "Q: What versions of OpenFlow does Open vSwitch support?'' in the Open vSwitch FAQ. iykyk 📖

• add-meter switch meter — adds a meter entry to switch's tables. The meter syntax is, again, described in section Meter Syntax, below. go off 💖
• mod-meter switch meter — modifies a meter that already exists. glow-up, not a rebirth ✨
• del-meters switch [meter] — deletes entries from switch's meter table. Wanna delete just one specific meter? Pass its number as meter. Otherwise, if meter is omitted — or if you literally write it as all — then every single meter gets deleted. all of them. periodt 💀
• dump-meters switch [meter] — prints entries from switch's meter table. Specific meter only? Give its number as meter. Otherwise, if meter is omitted, or if it's specified as all, then all meters get printed. 🫶
• meter-stats switch [meter] — prints meter statistics. meter can pin down a single meter with the syntax meter=id, or grab all of them with the syntax meter=all. 🌈
• meter-features switch — prints meter features. that's it, that's the whole vibe 👑

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🦋 OpenFlow Switch Bundle Command 🦋

So you wanna make transactional updates to both the flow table and the group table at the same time? That's literally what the bundle command is for, bestie. 🔥

file is a text file containing zero or more flow mods, group mods, or packet-outs, written in Flow Syntax, Group Syntax, or Packet-Out Syntax respectively. Each line has to be preceded by the flow, group, or packet-out keyword, correspondingly. Okay and here's the cute part:

• the flow keyword may optionally be followed by one of add, modify, modify_strict, delete, or delete_strict — and if you just give a bare flow, then add is what's assumed.
• same energy for the group keyword: it may optionally be followed by one of add, modify, add_or_mod, delete, insert_bucket, or remove_bucket — and yep, add is assumed if you give a bare group.
• bundle switch file — executes all the flow and group mods in file as one single atomic transaction against switch's tables. Every bundled mod runs in the order you specified them. no queue-jumping, no cutting in line 💅

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🧚 OpenFlow Switch Tunnel TLV Table Commands 🧚

Open vSwitch keeps a mapping table between tunnel option TLVs (defined by <class, type, length>) and NXM fields tun_metadatan, where n ranges from 0 to 63 — and you can operate on those bad boys for the purposes of matches, actions, etc. This TLV table works for Geneve option TLVs, or honestly any other protocol whose options are in the same TLV format as Geneve options. 🎀

The thing is: this mapping has to be explicitly specified by you, the user, through the following commands. No vibes-based auto-mapping here, sorry.

A TLV mapping gets specified with this syntax:

{class=class,type=type,len=length}->tun_metadatan

Once an option mapping exists for a given tun_metadatan, matching on that defined field becomes possible. Like, for example:

ovs-ofctl add-tlv-map br0 "{class=0xffff,type=0,len=4}->tun_metadata0"

ovs-ofctl add-flow br0 tun_metadata0=1234,actions=controller

⚠️ Do not change a mapping while it's actively being used by a flow. The result of doing that is undefined. like genuinely do not, bestie 😭

These commands are Nicira extensions to OpenFlow and they require Open vSwitch 2.5 or later. 📌

• add-tlv-map switch option[,option]... — adds each option to switch's tables. Duplicate fields? rejected. we don't do repeats here 🙈
• del-tlv-map switch [option[,option]]... — deletes each option from switch's table — or, if you don't specify any option, it deletes the whole option TLV mapping. Fields that aren't mapped are ignored, no drama. ✨
• dump-tlv-map switch — shows you the currently mapped fields in the switch's option table, plus the switch capabilities while it's at it. two-for-one 💖

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💜 OpenFlow Switch Monitoring Commands 💜

• snoop switch — connects to switch and prints, to the console, every single OpenFlow message it receives. 👀

But here's the twist, and it's kind of the main character detail: unlike other ovs-ofctl commands, if switch is the name of a bridge, then snoop connects to a Unix domain socket named /run/openvswitch/switch.snoop. ovs-vswitchd listens on a socket like that for each bridge, and it sends to it all the OpenFlow messages sent to or received from its configured OpenFlow controller. So basically, this command lets you spy on the OpenFlow protocol activity between a switch and its controller. iconic 🔥

When a switch has more than one controller configured, only the traffic to and from a single controller gets output. If none of the controllers is configured as a primary or a secondary (that's using a Nicira extension to OpenFlow 1.0 or 1.1, or a standard request in OpenFlow 1.2 or later), then a controller is chosen arbitrarily among them. The full priority list, since you asked:

1. if there's a primary controller, it's the chosen one;
2. otherwise, if there are any controllers that are not primaries or secondaries, one of those gets chosen arbitrarily;
3. otherwise, a secondary controller gets chosen arbitrarily.

This choice is made once, at connection time, and it does not change as controllers reconfigure their roles. set it and forget it ✨

Also: if a switch has no controller configured, or if the configured controller is disconnected, then no traffic is sent — so monitoring won't show you any traffic. it's giving silent treatment 😭

• monitor switch [miss-len] [invalid_ttl] [watch:[spec...]] — connects to switch and prints every OpenFlow message received to the console. Usually, switch should be the name of a bridge in the ovs-vswitchd database. Fair warning: this is available only in OpenFlow 1.0, as a Nicira extension. 📼

If miss-len is provided, ovs-ofctl sends an OpenFlow ``"set configuration"'' message at connection setup time that requests miss-len bytes of each packet that misses the flow table. Here's the catch — Open vSwitch does not send these (or other asynchronous messages) to an ovs-ofctl monitor client connection unless you specify a nonzero value on this argument. (So if miss-len isn't specified, very little traffic will ordinarily be printed. like, barely anything. tumbleweeds 💀)

If invalid_ttl is passed, ovs-ofctl sends an OpenFlow "set configuration"'' message at connection setup time that requests `INVALID_TTL_TO_CONTROLLER`, so that `ovs-ofctl monitor` can receive "packet-in"'' messages when TTL reaches zero on dec_ttl action. Only OpenFlow 1.1 and 1.2 support invalid_ttl; Open vSwitch also implements it for OpenFlow 1.0 as an extension. fancy 🎀

watch:[spec...] causes ovs-ofctl to send a ``"monitor request"'' Nicira extension message to the switch at connection setup time. That message makes the switch send you info about flow table changes as they happen. The following comma-separated spec syntax is available, bestie:

• !initial — do not report the switch's initial flow table contents.
• !add — do not report newly added flows.
• !delete — do not report deleted flows.
• !modify — do not report modifications to existing flows.
• !own — abbreviate changes made to the flow table by ovs-ofctl's own connection to the switch. (These could only occur using the ofctl/send command described below under RUNTIME MANAGEMENT COMMANDS.)
• !actions — do not report actions as part of flow updates.
• table=table — limits the monitoring to the table with the given table, which may be expressed as a number between 0 and 254 or (unless --no-names is specified) a name. By default, all tables are monitored. slay 🦋
• out_port=port — if set, only flows that output to port are monitored. The port may be an OpenFlow port number or a keyword (e.g. LOCAL).
• out_group=group — if set, only flows that output to group number group are monitored. Heads up: this field requires OpenFlow 1.4 (-OOpenFlow14) or later. 🔥
• field=value — monitors only flows that have field specified as the given value. Any syntax that's valid for matching on dump-flows may be used. 🌈

This command may be useful for debugging switch or controller implementations. And with watch:, it's particularly useful for observing how a controller updates flow tables. lowkey a whole vibe for debugging 👑

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💖 OpenFlow Switch and Controller Commands 💖

The following commands, just like the ones in the previous section, may be applied to OpenFlow switches using any of the connection methods described in that section. Unlike those commands though? These can also be applied to OpenFlow controllers. equal opportunity ✨

• probe target — sends a single OpenFlow echo-request message to target and waits for the response. With the -t or --timeout option, this command can test whether an OpenFlow switch or controller is up and running. vibe check, literally 🫶
• ping target [n] — sends a series of 10 echo request packets to target and times each reply. Each echo request packet consists of an OpenFlow header plus n bytes (default: 64) of randomly generated payload. This measures the latency of individual requests. ⏱️
• benchmark target n count — sends count echo request packets, each consisting of an OpenFlow header plus n bytes of payload, and waits for each response. Then it reports the total time required. This is a measure of the maximum bandwidth to target for round-trips of n-byte messages. bandwidth queen 💅

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🌸 Other Commands 🌸

• ofp-parse file — reads file (or stdin if file is -) as a series of OpenFlow messages in the binary format used on an OpenFlow connection, and prints them to the console. Super useful for printing OpenFlow messages you captured from a TCP stream. 🍓
• ofp-parse-pcap file [port...] — reads file, which has to be in the PCAP format used by network capture tools like tcpdump or wireshark. It extracts all the TCP streams for OpenFlow connections and prints the OpenFlow messages in those connections in human-readable format on stdout. detective mode activated 🔍💜

OpenFlow connections are distinguished by TCP port number. Non-OpenFlow packets are just, like, ignored bestie. By default, data on TCP ports 6633 and 6653 are considered to be OpenFlow. Specify one or more port arguments to override the default. 💅

This command cannot usefully print SSL/TLS encrypted traffic. And it does not understand IPv6. Not even a little. 😭

🦋 Flow Syntax 🦋

Some ovs-ofctl commands accept an argument that describes a flow or flows. Such flow descriptions comprise a series of field=value assignments, separated by commas or white space. (Embedding spaces into a flow description normally requires quoting to prevent the shell from breaking the description into multiple arguments — the shell is not a girl's girl about this, she will split on you. 🙈)

Flow descriptions should be in normal form. This means that a flow may only specify a value for an L3 field if it also specifies a particular L2 protocol, and that a flow may only specify an L4 field if it also specifies particular L2 and L3 protocol types. For example, if the L2 protocol type dl_type is wildcarded, then L3 fields nw_src, nw_dst, and nw_proto must also be wildcarded. Similarly, if dl_type or nw_proto (the L3 protocol type) is wildcarded, so must be the L4 fields tcp_dst and tcp_src. ovs-ofctl will warn about flows not in normal form. Consider this your vibe check. ✨

ovs-fields(7) describes the supported fields and how to match them. In addition to match fields, commands that operate on flows accept a few additional key-value pairs:

• table=table — for flow dump commands, limits the flows dumped to those in table, which may be expressed as a number between 0 and 255 or (unless --no-names is specified) a name. If not specified (or if 255 is specified as table), then flows in all tables are dumped.

For flow table modification commands, behavior varies based on the OpenFlow version used to connect to the switch, so buckle up:

• OpenFlow 1.0 — OpenFlow 1.0 does not support table for modifying flows. ovs-ofctl will exit with an error if table (other than table=255) is specified for a switch that only supports OpenFlow 1.0.

In OpenFlow 1.0, the switch chooses the table into which to insert a new flow. The Open vSwitch software switch always chooses table 0. Other Open vSwitch datapaths and other OpenFlow implementations may choose different tables. Rude, but true. 🤷‍♀️

The OpenFlow 1.0 behavior in Open vSwitch for modifying or removing flows depends on whether --strict is used. Without --strict, the command applies to matching flows in all tables. With --strict, the command will operate on any single matching flow in any table; it will do nothing if there are matches in more than one table. (The distinction between these behaviors only matters if non-OpenFlow 1.0 commands were also used, because OpenFlow 1.0 alone cannot add flows with the same matching criteria to multiple tables.)

• OpenFlow 1.0 with table_id extension — Open vSwitch implements an OpenFlow extension that allows the controller to specify the table on which to operate. ovs-ofctl automatically enables the extension when table is specified and OpenFlow 1.0 is used. ovs-ofctl automatically detects whether the switch supports the extension. As of this writing, this extension is only known to be implemented by Open vSwitch. main character extension honestly 👑

With this extension, ovs-ofctl operates on the requested table when table is specified, and acts as described for OpenFlow 1.0 above when no table is specified (or for table=255).

• OpenFlow 1.1 — OpenFlow 1.1 requires flow table modification commands to specify a table. When table is not specified (or table=255 is specified), ovs-ofctl defaults to table 0.
• OpenFlow 1.2 and later — OpenFlow 1.2 and later allow flow deletion commands, but not other flow table modification commands, to operate on all flow tables, with the behavior described above for OpenFlow 1.0.

• duration=..., n_packet=..., n_bytes=... — ovs-ofctl ignores assignments to these "fields" to allow output from the dump-flows command to be used as input for other commands that parse flows. Iconic recycling behaviour actually 🎀

The add-flow, add-flows, and mod-flows commands require an additional field, which must be the final field specified:

• actions=[action][,action...] — Specifies a comma-separated list of actions to take on a packet when the flow entry matches. If no action is specified, then packets matching the flow are dropped. See ovs-actions(7) for details on the syntax and semantics of actions.

An opaque identifier called a cookie can be used as a handle to identify a set of flows:

• cookie=value — a cookie can be associated with a flow using the add-flow, add-flows, and mod-flows commands. value can be any 64-bit number and need not be unique among flows. If this field is omitted, a default cookie value of 0 is used.
• cookie=value/mask — when using NXM, the cookie can be used as a handle for querying, modifying, and deleting flows. value and mask may be supplied for the del-flows, mod-flows, dump-flows, and dump-aggregate commands to limit matching cookies. A 1-bit in mask indicates that the corresponding bit in cookie must match exactly, and a 0-bit wildcards that bit. A mask of -1 may be used to exactly match a cookie.

The mod-flows command can update the cookies of flows that match a cookie by specifying the cookie field twice (once with a mask for matching and once without to indicate the new value):

ovs-ofctl mod-flows br0 cookie=1,actions=normal

Change all flows' cookies to 1 and change their actions to normal. Slay, batch edit 💅

ovs-ofctl mod-flows br0 cookie=1/-1,cookie=2,actions=normal

Update cookies with a value of 1 to 2 and change their actions to normal.

The ability to match on cookies was added in Open vSwitch 1.5.0.

The following additional field sets the priority for flows added by the add-flow and add-flows commands. For mod-flows and del-flows when --strict is specified, priority must match along with the rest of the flow specification. For mod-flows without --strict, priority is only significant if the command creates a new flow, that is, non-strict mod-flows does not match on priority and will not change the priority of existing flows. Other commands do not allow priority to be specified.

• priority=value — the priority at which a wildcarded entry will match in comparison to others. value is a number between 0 and 65535, inclusive. A higher value will match before a lower one. An exact-match entry will always have priority over an entry containing wildcards, so it has an implicit priority value of 65535. When adding a flow, if the field is not specified, the flow's priority will default to 32768.

OpenFlow leaves behavior undefined when two or more flows with the same priority can match a single packet. Some users expect "sensible" behavior, such as more specific flows taking precedence over less specific flows, but OpenFlow does not specify this and Open vSwitch does not implement it. Users should therefore take care to use priorities to ensure the behavior that they expect. So like... actually use the priorities, bestie. Don't make it weird. 😭

The add-flow, add-flows, and mod-flows commands support the following additional options. These options affect only new flows. Thus, for add-flow and add-flows, these options are always significant, but for mod-flows they are significant only if the command creates a new flow, that is, their values do not update or affect existing flows.

• idle_timeout=seconds — causes the flow to expire after the given number of seconds of inactivity. A value of 0 (the default) prevents a flow from expiring due to inactivity.
• hard_timeout=seconds — causes the flow to expire after the given number of seconds, regardless of activity. A value of 0 (the default) gives the flow no hard expiration deadline.
• importance=value — sets the importance of a flow. The flow entry eviction mechanism can use importance as a factor in deciding which flow to evict. A value of 0 (the default) makes the flow non-evictable on the basis of importance. Specify a value between 0 and 65535.

Only OpenFlow 1.4 and later support importance. 🫶

• send_flow_rem — marks the flow with a flag that causes the switch to generate a "flow removed" message and send it to interested controllers when the flow later expires or is removed.
• check_overlap — forces the switch to check that the flow match does not overlap that of any different flow with the same priority in the same table. (This check is expensive so it is best to avoid it. ngl, highkey expensive. 💀)
• reset_counts — when this flag is specified on a flow being added to a switch, and the switch already has a flow with an identical match, an OpenFlow 1.2 (or later) switch resets the flow's packet and byte counters to 0. Without the flag, the packet and byte counters are preserved.

OpenFlow 1.0 and 1.1 switches always reset counters in this situation, as if reset_counts were always specified.

Open vSwitch 1.10 added support for reset_counts.

• no_packet_counts, no_byte_counts — adding these flags to a flow advises an OpenFlow 1.3 (or later) switch that the controller does not need packet or byte counters, respectively, for the flow. Some switch implementations might achieve higher performance or reduce resource consumption when these flags are used. These flags provide no benefit to the Open vSwitch software switch implementation.

OpenFlow 1.2 and earlier do not support these flags.

Open vSwitch 1.10 added support for no_packet_counts and no_byte_counts.

The dump-flows, dump-aggregate, del-flow and del-flows commands support these additional optional fields:

• out_port=port — if set, a matching flow must include an output action to port, which must be an OpenFlow port number or name (e.g. local).
• out_group=group — if you set this, then a matching flow has to include a group action naming group, and group has to be an actual OpenFlow group number 💖. This field is supported in Open vSwitch 2.5 and later, and it requires OpenFlow 1.1 or later. iykyk.

🌸 Table Entry Output 🌸

The dump-tables and dump-aggregate commands spill the tea on the entries in a datapath's tables. Every line of output is a flow entry, exactly like the ones described in Flow Syntax above, plus a few extra fields:

• duration=secs — the time, in seconds, that the entry has been sitting in the table. secs gives you as much precision as the switch provides, possibly down to nanosecond resolution ✨.
• n_packets — the number of packets that have matched the entry.
• n_bytes — the total number of bytes from the packets that have matched the entry 💜.

The following extra fields show up only if the switch is Open vSwitch 1.6 or later and the NXM flow format is used to dump the flow (peep the description of the --flow-format option below). Heads up bestie: the values of these extra fields are approximations only, and in particular idle_age will sometimes become nonzero even for busy flows 😭.

• hard_age=secs — the integer number of seconds since the flow was added or modified. hard_age is displayed only if it differs from the integer part of duration. (It's separate from duration because mod-flows restarts the hard_timeout timer without zeroing duration.) 🎀
• idle_age=secs — the integer number of seconds that have passed without any packets passing through the flow.

🦋 Packet-Out Syntax 🦋

The ovs-ofctl bundle command accepts packet-outs to be specified in the bundle file. Each packet-out is a series of field=value assignments, separated by commas or white space. (Embedding spaces into a packet-out description normally requires quoting to prevent the shell from breaking the description into multiple arguments.) Unless noted otherwise, only the last instance of each field is honoured. This same syntax is also supported by the ovs-ofctl packet-out command 🫶.

• in_port=port — the port number to be considered the in_port when processing actions. This can be any valid OpenFlow port number, or any of LOCAL, CONTROLLER, or NONE. This field is required 👑.
• pipeline_field=value — optionally, you can specify a list of pipeline fields for a packet-out message. The supported pipeline fields include tunnel fields and register fields as defined in ovs-fields(7).
• packet=hex-string — the actual packet to send, expressed as a string of hexadecimal bytes. This field is required.
• actions=[action][,action...] — the syntax of actions is identical to the actions= field described in Flow Syntax above. Specifying actions= is optional, but omitting actions is interpreted as a drop, so the packet will not be sent anywhere from the switch 💀. actions must be specified at the end of each line, like for flow mods.

💅 Group Syntax 💅

Some ovs-ofctl commands accept an argument that describes a group or groups. Such group descriptions are a series of field=value assignments, separated by commas or white space. (Embedding spaces into a group description normally requires quoting to prevent the shell from breaking the description into multiple arguments.) Unless noted otherwise only the last instance of each field is honoured ✨.

• group_id=id — the integer group id of the group. When this field is specified in del-groups or dump-groups, the keyword all may be used to designate all groups. This field is required.
• type=type — the type of the group. The add-group, add-groups and mod-groups commands require this field. It is prohibited for other commands. The following keywords designate the allowed types:
  • all — execute all buckets in the group.
  • select — execute one bucket in the group, balancing across the buckets according to their weights. To select a bucket, for each live bucket, Open vSwitch hashes flow data with the bucket ID and multiplies by the bucket weight to obtain a ``score,'' and then selects the bucket with the highest score. Use selection_method to control the flow data used for selection 🎯.
  • indirect — executes the one bucket in the group.
  • ff, fast_failover — executes the first live bucket in the group which is associated with a live port or group.
• command_bucket_id=id — the bucket to operate on. The insert-buckets and remove-buckets commands require this field. It is prohibited for other commands. id may be an integer or one of the following keywords:
  • all — operate on all buckets in the group. Only valid when used with the remove-buckets command, in which case the effect is to remove all buckets from the group.
  • first — operate on the first bucket present in the group. In the case of the insert-buckets command the effect is to insert new bucets just before the first bucket already present in the group; or to replace the buckets of the group if there are no buckets already present in the group. In the case of the remove-buckets command the effect is to remove the first bucket of the group; or do nothing if there are no buckets present in the group.
  • last — operate on the last bucket present in the group. In the case of the insert-buckets command the effect is to insert new bucets just after the last bucket already present in the group; or to replace the buckets of the group if there are no buckets already present in the group. In the case of the remove-buckets command the effect is to remove the last bucket of the group; or do nothing if there are no buckets present in the group.

If id is an integer then it should correspond to the bucket_id of a bucket present in the group. In case of the insert-buckets command the effect is to insert buckets just before the bucket in the group whose bucket_id is id. In case of the iremove-buckets command the effect is to remove the in the group whose bucket_id is id. It is an error if there is no bucket persent group in whose bucket_id is id. 😭 ik it's a mouthful but that's literally what it says.

• selection_method=method — the selection method used to select a bucket for a select group. This is a string of 1 to 15 bytes in length known to lower layers. This field is optional for add-group, add-groups and mod-group commands on groups of type select. Prohibited otherwise. If no selection method is specified, Open vSwitch up to release 2.9 applies the hash method with default fields. From 2.10 onwards Open vSwitch defaults to the dp_hash method with symmetric L3/L4 hash algorithm, as long as the weighted group buckets can be mapped to dp_hash values with sufficient accuracy. In 2.10 this was restricted to a maximum of 64 buckets, and in 2.17 the limit was raised to 256 buckets. In those rare cases Open vSwitch 2.10 and later fall back to the hash method with the default set of hash fields 🌈.
  • dp_hash — use a datapath computed hash value. The hash algorithm varies across different datapath implementations. dp_hash uses the upper 32 bits of the selection_method_param as the datapath hash algorithm selector. The supported values are 0 (corresponding to hash computation over the IP 5-tuple) and 1 (corresponding to a symmetric hash computation over the IP 5-tuple). Selecting specific fields with the fields option is not supported with dp_hash). The lower 32 bits are used as the hash basis.

Using dp_hash has the advantage that it does not require the generated datapath flows to exact match any additional packet header fields. For real though — for example, even if multiple TCP connections thus hashed to different select group buckets have different source port numbers, generally all of them would be handled with a small set of already established datapath flows, resulting in less latency for TCP SYN packets. The downside is that the shared datapath flows must match each packet twice, as the datapath hash value calculation happens only when needed, and a second match is required to match some bits of its value. This double-matching incurs a small additional latency cost for each packet, but this latency is orders of magnitude less than the latency of creating new datapath flows for new TCP connections 🔥.

• hash — use a hash computed over the fields specified with the fields option, see below. If no hash fields are specified, hash defaults to a symmetric hash over the combination of MAC addresses, VLAN tags, Ether type, IP addresses and L4 port numbers. hash uses the selection_method_param as the hash basis.

Note that the hashed fields become exact matched by the datapath flows 👀. For example, if the TCP source port is hashed, the created datapath flows will match the specific TCP source port value present in the packet received. Since each TCP connection generally has a different source port value, a separate datapath flow will be need to be inserted for each TCP connection thus hashed to a select group bucket.

This option uses a Netronome OpenFlow extension which is only supported when using Open vSwitch 2.4 and later with OpenFlow 1.5 and later.

• selection_method_param=param — 64-bit integer parameter to the selection method selected by the selection_method field. The parameter's use is defined by the lower-layer that implements the selection_method. It is optional if the selection_method field is specified as a non-empty string. Prohibited otherwise. The default value is zero 💫.

Okay so this option uses a Netronome OpenFlow extension that’s only supported when you’re using Open vSwitch 2.4 and later with OpenFlow 1.5 and later. No cap.

• fields=field and fields(field[=mask]...) — These are the field parameters for whatever selection method the selection_method field picked. The syntax is described in Flow Syntax, with the extra restrictions that if a value is provided it’s treated as a wildcard mask, and wildcard masks following a slash are prohibited. The pre-requisites of fields must be provided by any flows that output to the group. The use of the fields is defined by the lower-layer that implements the selection_method. They’re optional if the selection_method field is specified as hash, and prohibited otherwise. The default is no fields.

Heads up again, bestie: this option will use a Netronome OpenFlow extension which is only supported when using Open vSwitch 2.4 and later with OpenFlow 1.5 and later. 💅

• bucket=bucket_parameters — The add-group, add-groups and mod-group commands require at least one bucket field. Bucket fields must appear after all other fields. Multiple bucket fields are how you specify multiple buckets. The order in which buckets are specified corresponds to their order in the group. If the type of the group is indirect then only one group may be specified. bucket_parameters consists of a list of field=value assignments, separated by commas or white space, followed by a comma-separated list of actions. The fields for bucket_parameters are:
  • bucket_id=id — The 32-bit integer group id of the bucket. Values greater than 0xffffff00 are reserved. This field was added in Open vSwitch 2.4 to conform with the OpenFlow 1.5 specification. It is not supported when earlier versions of OpenFlow are used. Open vSwitch will automatically allocate bucket ids when they are not specified.
  • actions=[action][,action...] — The syntax of actions is identical to the actions= field described in Flow Syntax above. Specifying actions= is optional; any unknown bucket parameter will be interpreted as an action.
  • weight=value — The relative weight of the bucket as an integer. This may be used by the switch during bucket select for groups whose type is select.
  • watch_port=port — Port used to determine liveness of group. This or the watch_group field is required for groups whose type is ff or fast_failover. This or the watch_group field can also be used for groups whose type is select.
  • watch_group=group_id — Group identifier of group used to determine liveness of group. This or the watch_port field is required for groups whose type is ff or fast_failover. This or the watch_port field can also be used for groups whose type is select.

🎀 Meter Syntax 🎀

The meter table commands accept an argument that describes a meter. Such meter descriptions comprise a series of field=value assignments, separated by commas or white space. (Embedding spaces into a group description normally requires quoting to prevent the shell from breaking the description into multiple arguments.) Unless noted otherwise, only the last instance of each field is honoured. Periodt.

• meter=id — The identifier for the meter. An integer is used to specify a user-defined meter. In addition, the keywords all, controller, and slowpath are also supported as virtual meters. The controller and slowpath virtual meters apply to packets sent to the controller and to the OVS userspace, respectively.

When this field is specified in del-meter, dump-meter, or meter-stats, the keyword all may be used to designate all meters. This field is required, except for meter-stats, which dumps all stats when this field is not specified.

• kbps, pktps — The unit for the rate and burst_size band parameters. kbps specifies kilobits per second, and pktps specifies packets per second. A unit is required for the add-meter and mod-meter commands.
• burst — If set, enables burst support for meter bands through the burst_size parameter.
• stats — If set, enables the collection of meter and band statistics.
• bands=band_parameters — The add-meter and mod-meter commands require at least one band specification. Bands must appear after all other fields.
  • type=type — The type of the meter band. This keyword starts a new band specification. Each band specifies a rate above which the band is to take some action. The action depends on the band type. If multiple bands’ rate is exceeded, then the band with the highest rate among the exceeded bands is selected. The following keywords designate the allowed meter band types:
    • drop — Drop packets exceeding the band’s rate limit.

The other band_parameters are:

• rate=value — The relative rate limit for this band, in kilobits per second or packets per second, depending on whether kbps or pktps was specified.
• burst_size=size — If burst is specified for the meter entry, configures the maximum burst allowed for the band in kilobits or packets, depending on whether kbps or pktps was specified. If unspecified, the switch is free to select some reasonable value depending on its configuration.

✨ OPTIONS ✨

• --strict — Uses strict matching when running flow modification commands. Very demure, very strict.
• --names, --no-names — Every OpenFlow port has a name and a number, and every OpenFlow flow table has a number and sometimes a name. By default, ovs-ofctl commands accept both port and table names and numbers, and they display port and table names if ovs-ofctl is running on an interactive console, numbers otherwise. With --names, ovs-ofctl commands both accept and display port and table names; with --no-names, commands neither accept nor display port and table names.

If a port or table name contains special characters or might be confused with a keyword within a flow, it may be enclosed in double quotes (escaped from the shell). If necessary, JSON-style escape sequences may be used inside quotes, as specified in RFC 7159. When it displays port and table names, ovs-ofctl quotes any name that does not start with a letter followed by letters or digits.

Open vSwitch added support for port names and these options. Open vSwitch 2.10 added support for table names. Earlier versions always behaved as if --no-names were specified.

Open vSwitch does not place its own limit on the length of port names, but OpenFlow limits port names to 15 bytes. Because ovs-ofctl uses OpenFlow to retrieve the mapping between port names and numbers, names longer than this limit will be truncated for both display and acceptance. Truncation can also cause long names that are different to appear to be the same; when a switch has two ports with the same (truncated) name, ovs-ofctl refuses to display or accept the name, using the number instead.

OpenFlow and Open vSwitch limit table names to 32 bytes.

• --stats, --no-stats — The dump-flows command by default, or with --stats, includes flow duration, packet and byte counts, and idle and hard age in its output. With --no-stats, it omits all of these, as well as cookie values and table IDs if they are zero. It’s giving less is more.
• --read-only — Do not execute read/write commands. Look, don’t touch.
• --bundle — Execute flow mods as an OpenFlow 1.4 atomic bundle transaction.
  • Within a bundle, all flow mods are processed in the order they appear and as a single atomic transaction, meaning that if one of them fails, the whole transaction fails and none of the changes are made to the switch’s flow table, and that each given datapath packet traversing the OpenFlow tables sees the flow tables either as before the transaction, or after all the flow mods in the bundle have been successfully applied.
  • The beginning and the end of the flow table modification commands in a bundle are delimited with OpenFlow 1.4 bundle control messages, which makes it possible to stream the included commands without explicit OpenFlow barriers, which are otherwise used after each flow table modification command. This may make large modifications execute faster as a bundle.
  • Bundles require OpenFlow 1.4 or higher. An explicit -O OpenFlow14 option is not needed, but you may need to enable OpenFlow 1.4 support for OVS by setting the OVSDB protocols column in the bridge table.
• -O [version[,version]...], --protocols=[version[,version]...] — Sets the OpenFlow protocol versions that are allowed when establishing an OpenFlow session.

These protocol versions are enabled by default:

• OpenFlow10, for OpenFlow 1.0.

The following protocol versions are generally supported, but for compatibility with older versions of Open vSwitch they are not enabled by default:

• OpenFlow11, for OpenFlow 1.1.
• OpenFlow12, for OpenFlow 1.2.
• OpenFlow13, for OpenFlow 1.3.
• OpenFlow14, for OpenFlow 1.4.
• OpenFlow15, for OpenFlow 1.5.

• -F format[,format...], --flow-format=format[,format...] — ovs-ofctl supports the following individual flow formats, any number of which may be listed as format:
  • OpenFlow10-table_id — This is the standard OpenFlow 1.0 flow format. All OpenFlow switches and all versions of Open vSwitch support this flow format.

🔥 OpenFlow10+table_id

Okay so this one is literally the standard OpenFlow 1.0 flow format plus a little Nicira extension that lets ovs-ofctl say which flow table a particular flow should land in. Open vSwitch 1.2 and later support it, periodt. 💅

🌸 NXM-table_id (Nicira Extended Match)

This Nicira extension to OpenFlow is flexible and extensible, bestie — it's giving main character energy. It supports all the Nicira flow extensions, like tun_id and registers. Open vSwitch 1.1 and later support this flow format. ✨

🦋 NXM+table_id (Nicira Extended Match)

This one combines Nicira Extended match with the ability to place a flow in a specific table. Open vSwitch 1.2 and later support this flow format. Slay. 🎀

👑 OXM-OpenFlow12, OXM-OpenFlow13, OXM-OpenFlow14, OXM-OpenFlow15

These are the standard OXM (OpenFlow Extensible Match) flow format in OpenFlow 1.2 and later. Iconic, no cap. ⭐

ovs-ofctl also supports these abbreviations for collections of flow formats:

• any — literally any supported flow format. 💖
• OpenFlow10 — means OpenFlow10-table_id or OpenFlow10+table_id.
• NXM — means NXM-table_id or NXM+table_id.
• OXM — means OXM-OpenFlow12, OXM-OpenFlow13, or OXM-OpenFlow14.

For commands that modify the flow table, ovs-ofctl by default negotiates the most widely supported flow format that supports the flows being added. For commands that query the flow table, ovs-ofctl by default uses the most advanced format supported by the switch. 🧠✨

This option, where format is a comma-separated list of one or more of the formats listed above, limits ovs-ofctl's choice of flow format. If a command cannot work as requested using one of the specified flow formats, ovs-ofctl will report a fatal error. 😭 (Vibe check failed, basically.)

-P format

--packet-in-format=format

ovs-ofctl supports the following ``packet-in'' formats, in order of increasing capability:

• standard — This uses the OFPT_PACKET_IN message, the standard ``packet-in'' message for any given OpenFlow version. Every OpenFlow switch that supports a given OpenFlow version supports this format.
• nxt_packet_in — This uses the NXT_PACKET_IN message, which adds many of the capabilities of the OpenFlow 1.1 and later ``packet-in'' messages before those OpenFlow versions were available in Open vSwitch. Open vSwitch 1.1 and later support this format. Only Open vSwitch 2.6 and later, however, support it for OpenFlow 1.1 and later (but there is little reason to use it with those versions of OpenFlow).
• nxt_packet_in2 — This uses the NXT_PACKET_IN2 message, which is extensible and should avoid the need to define new formats later. In particular, this format supports passing arbitrary user-provided data to a controller using the userdata option on the controller action. Open vSwitch 2.6 and later support this format. 🫶

Without this option, ovs-ofctl prefers nxt_packet_in2 if the switch supports it. Otherwise, if OpenFlow 1.0 is in use, ovs-ofctl prefers nxt_packet_in if the switch supports it. Otherwise, ovs-ofctl falls back to the standard packet-in format. When this option is specified, ovs-ofctl insists on the selected format — no negotiating, bestie. If the switch does not support the requested format, ovs-ofctl will report a fatal error. 💀

Before version 2.6, Open vSwitch called standard format openflow10 and nxt_packet_in format nxm, and ovs-ofctl still accepts these names as synonyms. (The name openflow10 was a misnomer because this format actually varies from one OpenFlow version to another; it is not consistently OpenFlow 1.0 format. Similarly, when nxt_packet_in2 was introduced, the name nxm became confusing because it also uses OXM/NXM.) 🙈

This option affects only the monitor command.

--timestamp

Prints a timestamp before each received packet. This option only affects the monitor, snoop, and ofp-parse-pcap commands. ⏰

-m

--more

Increases the verbosity of OpenFlow messages printed and logged by ovs-ofctl commands. Specify this option more than once to increase verbosity further. 🗣️🔥

--sort[=field]

--rsort[=field]

Display output sorted by flow field in ascending (--sort) or descending (--rsort) order, where field is any of the fields that are allowed for matching or priority to sort by priority. When field is omitted, the output is sorted by priority. Specify these options multiple times to sort by multiple fields. 🎀

Any given flow will not necessarily specify a value for a given field. This requires special treatement:

• A flow that does not specify any part of a field that is used for sorting is sorted after all the flows that do specify the field. For example, --sort=tcp_src will sort all the flows that specify a TCP source port in ascending order, followed by the flows that do not specify a TCP source port at all.
• A flow that only specifies some bits in a field is sorted as if the wildcarded bits were zero. For example, --sort=nw_src would sort a flow that specifies nw_src=192.168.0.0/24 the same as nw_src=192.168.0.0.

These options currently affect only dump-flows output.

---

🌈 Daemon Options 🌈

The following options are valid on POSIX based platforms. 🐧

--pidfile[=pidfile]

Causes a file (by default, ovs-ofctl.pid) to be created indicating the PID of the running process. If the pidfile argument is not specified, or if it does not begin with /, then it is created in /run/openvswitch. 📁

If --pidfile is not specified, no pidfile is created.

--overwrite-pidfile

By default, when --pidfile is specified and the specified pidfile already exists and is locked by a running process, ovs-ofctl refuses to start. Specify --overwrite-pidfile to cause it to instead overwrite the pidfile. 💅

When --pidfile is not specified, this option has no effect.

--detach

Runs ovs-ofctl as a background process. The process forks, and in the child it starts a new session, closes the standard file descriptors (which has the side effect of disabling logging to the console), and changes its current directory to the root (unless --no-chdir is specified). After the child completes its initialization, the parent exits. ovs-ofctl detaches only when executing the monitor or snoop commands. 🦋

--monitor

Creates an additional process to monitor the ovs-ofctl daemon. If the daemon dies due to a signal that indicates a programming error (SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV, SIGXCPU, or SIGXFSZ) then the monitor process starts a new copy of it. If the daemon dies or exits for another reason, the monitor process exits. 👀

This option is normally used with --detach, but it also functions without it.

--no-chdir

By default, when --detach is specified, ovs-ofctl changes its current working directory to the root directory after it detaches. Otherwise, invoking ovs-ofctl from a carelessly chosen directory would prevent the administrator from unmounting the file system that holds that directory. 😬

Specifying --no-chdir suppresses this behavior, preventing ovs-ofctl from changing its current working directory. This may be useful for collecting core files, since it is common behavior to write core dumps into the current working directory and the root directory is not a good directory to use. 🗂️

This option has no effect when --detach is not specified.

--no-self-confinement

By default daemon will try to self-confine itself to work with files under well-known directories determined during build. It is better to stick with this default behavior and not to use this flag unless some other Access Control is used to confine daemon. Note that in contrast to other access control implementations that are typically enforced from kernel-space (e.g. DAC or MAC), self-confinement is imposed from the user-space daemon itself and hence should not be considered as a full confinement strategy, but instead should be viewed as an additional layer of security. 🔒✨

--user

Causes ovs-ofctl to run as a different user specified in "user:group", thus dropping most of the root privileges. Short forms "user" and ":group" are also allowed, with current user or group are assumed respectively. Only daemons started by the root user accepts this argument. 👑

On Linux, daemons will be granted CAP_IPC_LOCK and CAP_NET_BIND_SERVICES before dropping root privileges. Daemons that interact with a datapath, such as ovs-vswitchd, will be granted three additional capabilities, namely CAP_NET_ADMIN, CAP_NET_BROADCAST and CAP_NET_RAW. The capability change will apply even if the new user is root. 🔥

--unixctl=socket

Sets the name of the control socket on which ovs-ofctl listens for runtime management commands (see RUNTIME MANAGEMENT COMMANDS, below). If socket does not begin with /, it is interpreted as relative to /run/openvswitch. If --unixctl is not used at all, the default socket is /run/openvswitch/ovs-ofctl.pid.ctl, where pid is ovs-ofctl's process ID. 🎀

Specifying none for socket disables the control socket feature. 🚫

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🔐 Public Key Infrastructure Options 🔐

-p privkey.pem

--private-key=privkey.pem

Specifies a PEM file containing the private key used as ovs-ofctl's identity for outgoing SSL/TLS connections. 🗝️💖

-c cert.pem

--certificate=cert.pem

Specifies a PEM file containing a certificate that certifies the private key specified on -p or --private-key to be trustworthy. The certificate must be signed by the certificate authority (CA) that the peer in SSL/TLS connections will use to verify it. 📜✨

• -C cacert.pem, --ca-cert=cacert.pem — points at a PEM file with the CA cert that ovs-ofctl should use to verify certs handed over by SSL/TLS peers. This might be the same cert the peers use to verify the cert from -c or --certificate, or it might be a different one — depends on the PKI design, bestie. 🎀
• -C none, --ca-cert=none — disables verification of certs presented by SSL/TLS peers. Security risk alert: this means certs can’t be verified as belonging to known trusted hosts. 😭
• --ssl-server-name=servername — sets the server name used for TLS Server Name Indication (SNI). By default, the hostname from the connection string is used for SNI. This option lets you override the SNI hostname, which is useful when connecting through proxies or service meshes where the connection endpoint differs from the intended server name. ✨
• -v[spec], --verbose=[spec] — sets logging levels. With no spec, it sets the log level for every module and destination to dbg.

Otherwise, spec is a list of words separated by spaces, commas, or colons, with up to one from each category below:

• A valid module name, as displayed by the vlog/list command on ovs-appctl(8), limits the log level change to the specified module.
• syslog, console, or file limits the log level change to only the system log, only the console, or only a file, respectively. (If --detach is specified, ovs-ofctl closes its standard file descriptors, so logging to the console will have no effect.)
• off, emer, err, warn, info, or dbg controls the log level. Messages of the given severity or higher will be logged, and messages of lower severity will be filtered out. off filters out all messages. See ovs-appctl(8) for a definition of each log level.

Case is not significant within spec. 💅

Regardless of the log levels set for file, logging to a file will not take place unless --log-file is also specified (see below).

For compatibility with older versions of OVS, any is accepted as a word but has no effect.

• -v, --verbose — sets the maximum logging verbosity level, equivalent to --verbose=dbg. 🔥
• -vPATTERN:destination:pattern, --verbose=PATTERN:destination:pattern — sets the log pattern for destination to pattern. Refer to ovs-appctl(8) for a description of the valid syntax for pattern. 🦋
• -vFACILITY:facility, --verbose=FACILITY:facility — sets the RFC5424 facility of the log message. facility can be one of kern, user, mail, daemon, auth, syslog, lpr, news, uucp, clock, ftp, ntp, audit, alert, clock2, local0, local1, local2, local3, local4, local5, local6, or local7. If this option is not specified, daemon is used as the default for the local system syslog, and local0 is used while sending a message to the target provided via the --syslog-target option. 🎀
• --log-file[=file] — enables logging to a file. If file is specified, then it is used as the exact name for the log file. The default log file name used if file is omitted is /var/log/openvswitch/ovs-ofctl.log. 🍓
• --syslog-target=host:port — sends syslog messages to UDP port on host, in addition to the system syslog. The host must be a numerical IP address, not a hostname. No cap. 📡
• --syslog-method=method — specifies how syslog messages should be sent to the syslog daemon. These forms are supported:
  • libc — use the libc syslog() function. The downside is that libc adds a fixed prefix to every message before it is actually sent to the syslog daemon over the /dev/log UNIX domain socket.
  • unix:file — use a UNIX domain socket directly. It’s possible to specify an arbitrary message format with this option. However, rsyslogd 8.9 and older versions use a hard coded parser function anyway that limits UNIX domain socket use. If you want to use an arbitrary message format with older rsyslogd versions, then use a UDP socket to the localhost IP address instead.
  • udp:ip:port — use a UDP socket. With this method it’s possible to use an arbitrary message format also with older rsyslogd. When sending syslog messages over a UDP socket, extra precaution needs to be taken into account: for example, the syslog daemon needs to be configured to listen on the specified UDP port, accidental iptables rules could be interfering with local syslog traffic, and there are some security considerations that apply to UDP sockets, but do not apply to UNIX domain sockets.
  • null — discards all messages logged to syslog.

The default is taken from the OVS_SYSLOG_METHOD environment variable; if it is unset, the default is libc. 🫶

• --color[=when] — colorizes the output (for some commands). when can be never, always, or auto (the default). 🌈

Only some commands support output coloring. Color names and default colors may change in future releases.

The environment variable OVS_COLORS can be used to specify user-defined colors and other attributes used to highlight various parts of the output. If set, its value is a colon-separated list of capabilities that defaults to ac:01;31:dr=34:le=31:pm=36:pr=35:sp=33:vl=32. Supported capabilities were initially designed for coloring flows from the ovs-ofctl dump-flows switch command, and they are as follows:

• ac=01;31 — SGR substring for the actions= keyword in a flow. The default is a bold red text foreground.
• dr=34 — SGR substring for the drop keyword. The default is a dark blue text foreground.
• le=31 — SGR substring for the learn= keyword in a flow. The default is a red text foreground.
• pm=36 — SGR substring for flow match attribute names. The default is a cyan text foreground.
• pr=35 — SGR substring for keywords in a flow that are followed by arguments inside parentheses. The default is a magenta text foreground.
• sp=33 — SGR substring for some special keywords in a flow, notably: table=, priority=, load:, output:, move:, group:, CONTROLLER:, set_field:, resubmit:, exit. The default is a yellow text foreground.
• vl=32 — SGR substring for a lone flow match attribute with no field name. The default is a green text foreground.

See the Select Graphic Rendition (SGR) section in the documentation of the text terminal that is used for permitted values and their meaning as character attributes. ✨

• -h, --help — prints a brief help message to the console. 🎀
• -V, --version — prints version information to the console. 👑

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🔮 RUNTIME MANAGEMENT COMMANDS 🔮

ovs-appctl(8) can send commands to a running ovs-ofctl process. The supported commands are listed below. 🫶

• exit — causes ovs-ofctl to gracefully terminate. This command applies only when executing the monitor or snoop commands. 💅
• ofctl/set-output-file file — causes all subsequent output to go to file instead of stderr. This command applies only when executing the monitor or snoop commands. 📁
• ofctl/send ofmsg... — sends each ofmsg, specified as a sequence of hex digits that express an OpenFlow message, on the OpenFlow connection. This command is useful only when executing the monitor command. 📨
• ofctl/packet-out packet-out — sends an OpenFlow PACKET_OUT message specified in Packet-Out Syntax, on the OpenFlow connection. See the Packet-Out Syntax section for more information. This command is useful only when executing the monitor command. 🎀
• ofctl/barrier — sends an OpenFlow barrier request on the OpenFlow connection and waits for a reply. This command is useful only for the monitor command. 🛑

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💖 EXAMPLES 💖

The following examples assume that ovs-vswitchd has a bridge named br0 configured. 🦋

• ovs-ofctl dump-tables br0 — prints out the switch’s table stats. (This is more interesting after some traffic has passed through.) 📊
• ovs-ofctl dump-flows br0 — prints the flow entries in the switch. 🌸
• ovs-ofctl add-flow table=0 actions=learn(table=1,hard_timeout=10, NXM_OF_VLAN_TCI[0..11],output:NXM_OF_IN_PORT[]), resubmit(,1) ovs-ofctl add-flow table=1 priority=0 actions=flood Implements a level 2 MAC learning switch using the learn. 🧚

Here’s that first bit in a clean code block so the line break stays exactly where it belongs:

ovs-ofctl add-flow table=0 actions=learn(table=1,hard_timeout=10,
NXM_OF_VLAN_TCI[0..11],output:NXM_OF_IN_PORT[]), resubmit(,1)
ovs-ofctl add-flow  table=1 priority=0 actions=flood

• ovs-ofctl add-flow br0 'table=0,priority=0 actions=load:3->NXM_NX_REG0[0..15],learn(table=0,priority=1,idle_timeout=10,NXM_OF_ETH_SRC[],NXM_OF_VLAN_TCI[0..11],output:NXM_NX_REG0[0..15]),output:2 — in this use of a learn action, the first packet from each source MAC will be sent to port 2. Subsequent packets will be output to port 3, with an idle timeout of 10 seconds. NXM field names and match field names are both accepted, e.g. NXM_NX_REG0 or reg0 for the first register, and empty brackets may be omitted. 😭🔥

Exact command, no fixes, no edits:

ovs-ofctl add-flow br0 'table=0,priority=0 actions=load:3->NXM_NX_REG0[0..15],learn(table=0,priority=1,idle_timeout=10,NXM_OF_ETH_SRC[],NXM_OF_VLAN_TCI[0..11],output:NXM_NX_REG0[0..15]),output:2

Additional examples may be found documented as part of related sections. 💜

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🌈 SEE ALSO 🌈

ovs-fields(7), ovs-actions(7), ovs-appctl(8), ovs-vswitchd(8), ovs-vswitchd.conf.db(8) 🎀

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Footer vibes, bestie: source Open vSwitch, version 4.0.0, page ovs-ofctl(8) — iconic, no cap. 💅✨