DANTED.CONF(5)

📦
version 1.4.4 · 2 versions
, in ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 DANTED.CONF(5) — danted.conf 💖

okay bestie, welcome to the DANTED.CONF(5) manual page — it's giving config-file energy, and we're about to make it make sense. This is the syntax for the Dante server configuration file. 💅

✨ NAME ✨

danted.conf — Dante server configuration file syntax

🌸 DESCRIPTION 🌸

okay so the config file for the Dante server? It controls both access controls and logging. It's split into three parts: server settings, rules, and routes.

important bestie: server settings MUST come before rules and routes. No cap.

A line can be commented out using the standard comment character #. Periodt.

👑 SERVER SETTINGS 👑

The server settings control the generic behaviour of the server. Each keyword is separated from its value by a : character.

The following keywords are available:

  • clientmethod — A list of acceptable authentication methods for client-rules, listed in order of preference. These are authentication methods that are to be checked immediately after the SOCKS client has connected to Dante, and before any socks-negotiation has started.

Supported values are pam.address, pam.any, none, and rfc931 .

For all methods the authentication will be based on solely on the IP-address of the client, possibly in combination with a rfc931 ("ident") lookup towards the host the client is running on.

Any credentials provided during this pass will also be available for use in later socks-rules, when the socks-request from the client is evaluated.

The default value for this keyword is all methods that may be necessary for the later socks-based authentication methods, as specified as values to the global socksmethod keyword. Normally you should not need to set this keyword, as Dante will set it to the correct value by it self.

  • compatibility — With the sameport keyword, the server attempts to use the same port on the server's external side as the client used on the server's internal side. This is normally the default, but when this option is given it will be done with privileged ports also, meaning if a client connects to Dante from a privileged port, Dante will attempt to connect to the target destination from a privileged port too. There can be security issues involved with this, so normally this option should not be set.

The draft-5.05 keyword will enable usage of parts of the socks v5-05 draft. The only feature from this draft that Dante supports is the "USECLIENTSPORT" extension. Note that there is a conflicting interpretation of this extension, so enabling it might prevent clients using the conflicting interpretation from working correctly. Only affects UDP.

  • cpu — The CPU settings for the various type of Dante processes. Note that the possibility for configuring these settings depend on the platform Dante is running on. Not all platforms may provide support for these type of CPU settings.

There are four process types: mother, negotiate, request, and io.

The currently supported options are:

  • schedule.<process type>: <scheduling policy>/<priority>.

Example:

cpu.schedule.mother: SCHED_FIFO/20

The above requests that the kernel schedules the mother process(es) using a first-in, first-out policy, at priority 20.

The default is to not request any specific scheduling.

  • mask.<process type>: <cpu id 1> [cpu id 1 ...]/any.

Example:

cpu.mask.mother: any

Example:

cpu.mask.io: 0 1

The mask gives control over the CPU/cores on which the different process types will run. Specifying the default (all) allows the process type to run on any CPU id. Specifying one or more numeric CPU id limits the process to that set of CPUs.

The cpu keywords (schedule and mask) should in most cases not be necessary. If they are to be used, the io processes are where most of the work is done and adjusting the priority or CPU usage is what is likely to have the most significant performance effect client performance and overhead from the server. The other processes are primarily used during connection/session establishment and changes to settings for the non-io process types will primarily affect these operations.

The default is to not limit processes to any specific cpu.

  • debug — Print debug info to the logs. The value sets the debug level.
  • errorlog — This value can be set to receive only error-related logoutput. Note that this does not include client-specific errors, but only more serious "global" errors.

The possible values are the same as for the logoutput keyword mentioned below.

The intent is to have a special place that only serious errors are logged so that they can discovered quickly. The default is to not have any special place to log errors.

  • external — The address to be used for outgoing connections. The address given may be either an IP address or an interface name. Can be given multiple times for different addresses.
  • external.log.<loglevel>.error — See internal.log.<loglevel>.error. This option has an identical syntax and semantics, but applies to error related to the external interface side.
  • external.protocol — By default Dante will use the address families specified and available, and there is no need to set this keyword.

In some cases the operator may however wish to specify an address in a form that may include more than one address family, yet not wish for Dante to use all the address families available for that address form.

This will typically happen if the operator wishes to specify that Dante should use the addresses on a network interface card which has both IPv4 and IPv6 addresses configured, yet the operator wishes Dante to only use one of these two address families. The operator can then specify the address family he wants Dante too look for when expanding the interface name for IP-addresses to use.

Valid values for this keyword are: ipv4 and ipv6, indicating that Dante should only use the IPv4 address family or only the IPv6 address family, respectively. The default is to use both families, if available.

A corresponding keyword exists for the internal side (see internal.protocol).

  • external.rotation — If more than one external address is given, this governs which of the given addresses is selected as the source address for outgoing connections/packets. Note that regardless of which external rotation value is used, all external addresses that are to be used must be listed via the external keyword first.

Valid values are none (the default), route, and same-same.

none indicates the first address on the list of external addresses should be used.

route indicates the kernels routing table should be consulted to find out what the source address for a given destination will be, and might require you to set user.privileged to root. Note that route might create problems for ftp-clients using active ftp if the Dante bind extension is enabled for the ftp-client.

same-same indicates the source address for a given destination should be the same address as the Dante server accepted the clients connection on.

  • internal — The internal addresses. Connections will only be accepted on these addresses. The address given may be either an IP address or an interface name.
  • internal.log.<loglevel>.error — Specifies that certain system call failures, listed as symbolic errno values, or certain dns failures, listed as symbolic libresolv failure-codes, should be logged, possibly an extra time, at the log-level log-level.

Note that this only applies to errors on the internal interface side only.

A corresponding keyword exists for the external side (see external.log).

In addition to the standard errno and getaddrinfo(3) error symbols, the following special symbols are accepted:

  • no-route — Any error related to no route.
  • dns-any — Any error related to DNS/hostname-resolving.
  • system-any — Any system error. I.e., any errno value.
  • internal.protocol — See external.protocol. This option has an identical syntax and semantics, but applies to the internal interface, for addresses to listen to connections from clients on.
  • libwrap.hosts_access — If the server is compiled with libwrap support, determines whether the hosts_access() function should be used for access control. When enabled by setting this value to yes, the libwrap library determines if TCP connections or UDP packets should be immediately dropped or not, typically by consulting /etc/hosts.allow and /etc/hosts.deny. These checks are applied to all traffic, before the rule processing starts. The default value is no (disabled).
  • logoutput — This value controls where the server sends logoutput. It can be set to syslog[/facility], stdout, stderr, a filename, or a combination. The default is nowhere. Note that if errorlog is also set, there will be a overlap between what is logged there (errors only), and what will be logged here (errors, and everything else).
  • socksmethod — A list of acceptable authentication methods for socks-rules, listed in order of preference. It is thus important that you specify these in the desired order, normally with the more secure methods first.

Supported values are bsdauth, gssapi, none, pam.any, pam.address, pam.username, rfc931, and username,

If a method is not set in this list it will never be selected. The default is no methods, which means all socks-requests will be blocked.

See the section on AUTHENTICATION METHODS for an explanation of the different methods and their meaning.

  • srchost — This keyword allows you to configure a few options that relate to the srchost, i.e., the host the Dante server accepts the connections from.

With the nodnsmismatch keyword, the server will not accept connections from addresses having a mismatch between DNS IP address and hostname. Default is to accept them.

  • nodnsunknown — turn this on and the server will straight up refuse connections from addresses that have no DNS record. Default? It accepts them. (yes bestie, letting the DNS-less in is the default 💖)
  • checkreplyauth — makes the server double-check that the auth on bind-replies and udp-replies actually matches what's set in the rule and the global socksmethod. Normally you do NOT want auth on replies, because they're literally just replies going back to the socks-clients from non-socks clients, so only a tiny limited set of auth methods is even possible. 😭

The methods that work for TCP are the ones that don't involve the socks protocol at all, and they're listed up in the clientmethod section we already talked about. For UDP-replies? No methods can be used. None. Zero. Nada. 💀

Default is not to check the auth on replies.

  • timeout.connect — how many seconds the server will sit there waiting for a connect that it started on behalf of the socks-client to finish. Default is 30. Set it to 0 and it'll just use the system's default. ✨
  • timeout.io — how many seconds an established connection is allowed to just vibe there idle. Default is 0, which means forever. 👑 (also go peek at the -n option in the danted(8) manpage, it's related.)

You can set individual timeouts for TCP and UDP by sticking .<protocolname> onto io, i.e. timeout.io.tcp or timeout.io.udp.

You can also set individual timeouts inside rules using the exact same syntax. When you do that, the timeout set in the rule overrides the default timeouts for clients matching that rule. periodt.

  • timeout.negotiate — how many seconds a client gets to spend negotiating with the Dante server for a socks session before Dante just closes the connection on them. Default is 30. Set it to 0 for forever, though that is strongly discouraged. don't do it bestie, i'm begging 🙈
  • timeout.tcp_fin_wait — the timeout for the equivalent of TCP's FIN-WAIT-2. Default is 0, which means use the system's default (normally, no timeout).
  • udp.connectdst — enables or disables whether the server should try to connect UDP sockets to the destination. Valid values are yes and no.

Default is yes, which makes UDP faster 🚀 but may not play nice with some UDP-based application protocols, because it means the server can only receive packets from the destination address.

The socket only stays connected as long as the client keeps sending UDP packets to a single destination address. The moment packets go to multiple destinations, the socket stops being connected and replies can come in from any destination. 💅

🫶 Userids 🫶

On platforms that provide a privilege-model Dante supports, the Dante server does not do userid-switching via the seteuid(2) system call. On other platforms, it's prudent to set the userid the Dante server uses to appropriate values. The Dante server can use two different userids — or three if it's compiled with libwrap support. Here they are, bestie:

  • user.privileged — the username used for doing privileged operations. If you need special privileges to read the danted.conf file, or to write the danted.pid file (you can create it manually before starting danted), or you have anything in your config that requires binding privileged TCP/UDP ports (ports below 1024), or you use some sort of password-based authentication — then this probably needs to be set to root.

If not, you can probably set it to the same value as user.unprivileged. ✨

  • user.unprivileged — the user the server runs as most of the time. This should be an id with as little privileges as possible. It's recommended that a separate userid is created just for this purpose. keep it humble, keep it locked down 🔒
  • user.libwrap — the user used to execute libwrap commands. Normally this should be the same as user.unprivileged.

✨ MODULES ✨

The following modules are supported by Dante. Modules are purchased separately from Inferno Nettverk A/S and may add extra functionality that most users don't even need. See the Dante homepage for more info. 💸

  • bandwidth — the bandwidth module gives you control over how much bandwidth the Dante server uses on behalf of different clients, or to different targets.
  • redirect — the redirect module gives you control over what addresses the server uses on behalf of the clients, and it also lets you redirect client requests to different addresses. slay.

🌈 SOCKET OPTIONS 🌈

The server supports setting a large number of low-level socket options on both incoming and outgoing traffic. Most users will not need to set any of these, but some might want to, to enable special network features or to perform various experiments. 🧪

Options can be set globally as defaults for all traffic, or set in the access control rules so they only affect clients and targets matching that given rule.

The socket options available vary between platforms, so while the server is being configured and built, the options that are available get determined. Currently, the following options should be detected, when available, for the specified protocol levels:

  • SOCKET — so_bindany, so_broadcast, so_debug, so_dontroute, so_jumbo, so_keepalive, so_oobinline, so_priority, so_rcvbuf, so_rcvbufforce, so_rcvlowat, so_sndbuf, so_sndbufforce, so_sndlowat, so_useloopback
  • TCP — tcp_cork, tcp_cwnd, tcp_init_cwnd, tcp_keepcnt, tcp_keepidle, tcp_keepintvl, tcp_linger2, tcp_maxrt, tcp_maxseg, tcp_md5sig, tcp_nodelay, tcp_noopt, tcp_nopush, tcp_sack_enable, tcp_stdurg, tcp_syncnt, tcp_window_clamp
  • UDP — udp_cork
  • IP — ip_auth_level, ip_dontfrag, ip_esp_network_level, ip_esp_trans_level, ip_freebind, ip_ipcomp_level, ip_minttl, ip_mtu_discover, ip_portrange, ip_recvtos, ip_tos, ip_ttl

The syntax for setting socket options goes like this:

<direction>.<level>.<option>: <value>

The value field corresponds to the value the socket option should be set to. For many socket options this is an integer value. The level and option values correspond to the socket names and protocol levels listed above. Both should be in lower-case.

The direction keyword specifies whether the socket option should be set for traffic on the internal or the external interface, and can have the values internal and external. For example, to set the IP_TOS socket option on outgoing traffic, you can use:

external.ip.ip_tos: 0x10

In this example the argument value (0x10) is specified as a hex value. For some of the socket options the value can also be set symbolically. Currently that's possible for the following options, with the listed values:

  • ip_portrange — ip_portrange_default, ip_portrange_low, ip_portrange_high

The IP_TOS socket option also supports this, but handling this option is somewhat complicated by the same bits having different meanings in different RFCs. 😵💫 This is handled with a subfield that indicates what type of argument should be used. The following subfields are defined and should be added to the name of the socket option as specified below:

  • ip_tos.dscp — af11 af12 af13 af21 af22 af23 af31 af32 af33 af41 af42 af43 cs0 cs1 cs2 cs3 cs4 cs5 cs6 cs7 ef
  • ip_tos.prec — netcontrol internetcontrol critic_ecp flashoverride flash immediate priority routine
  • ip_tos.tos — lowdelay throughput reliability

When numerical arguments are given to subfields, the values are shifted so they only apply to the subfield's bit range. The following example shows the different ways of setting IP_TOS to lowdelay on external traffic:

external.ip.ip_tos:     0x10       #base value, numerically
external.ip.ip_tos.tos: 0x08       #subfield, numerically
external.ip.ip_tos.tos: lowdelay   #subfield, symbolically

The first value sets the value directly, the second sets only the TOS bits, which are shifted relative to the base value. The final line sets the TOS value symbolically. ✨

This functionality gives you a huge amount of control over socket options, but it should not be used without some understanding of how the kernel allows the socket option to be set, and the limitations that apply when socket options are set as either defaults or in rules. 🫣

Setting a socket option in a client pass or socks-rules will cause any defaults to be overridden. Global options are set before bind() is called on internal sockets, or before connect() is called on external sockets. Options set in client rules are also applied before bind() is called on the internal socket, but they cannot be set for the external socket. For socks-rules, both external and internal options can be set, but because the socks-request must be interpreted before the rules can be evaluated, socket options can only be set on internal sockets after the connection has been received.

Some socket options must be set before a connection has been established, while others can only be set after a connection has been established. Others can be set at any time. the range, honestly 💅

Socket options that aren't listed above can also be set by specifying the socket option name numerically, for example:

external.ip.10:     0x12

In this example the socket option corresponding to the value 10 will be set. These numbers are platform dependent but can typically be figured out by looking at the appropriate system header files. Specifying options numerically might result in some warnings, but it lets you specify any socket option, as long as it takes a numerical argument. This is not the recommended approach for setting socket options, but it's a simple way of setting socket options the server doesn't directly support, like local kernel extensions. 🦋

💖 AUTHENTICATION METHODS 💖

okay bestie, so Dante can check who's knocking at the door in a bunch of different ways ✨ Here's the whole menu of methods it supports. Real talk though — depending on your platform, some installs of Dante might only support a subset of these 👀 so vibe check your own setup before you commit.

  • none — the "no thoughts, head empty" option 🫶 literally no form of authentication required. Just walk right in. Zero friction, zero security, main character energy.
  • username — classic bestie move: the client has to hand over a username and a password, and that combo has to match the username and password sitting in the system password file 📁. No match, no entry, periodt.
  • gssapi — this one needs you to actually set up a Kerberos environment first 🔥 but the payoff is it can give you strong encryption and authentication, depending on which gssapi settings you pick. You choose the settings, you choose the vibe 💅
  • rfc931 — requires the host that the socks client is running on to supply an rfc931 ("ident") username for that client 🦋 and that username has to match a username given in the system password file. Ident gotta ident, fr fr.
  • pam.address — IP-based (rhosts) PAM authentication ✨
  • pam.any — this one will try to match against any type of PAM authentication, depending on whatever info happens to be available at the moment 🙈 Normally it's of limited use, so instead of letting it wildcard around, you should just set the pam-based method(s) you actually want. Be specific, bestie, it's giving "choose your fighter" 🎀
  • pam.username — username/password-based PAM authentication 🔐 It's a lot like the username method, except the info gets passed to the PAM subsystem to handle the auth, instead of Dante going straight to the system password file itself. 💡 Heads up though: when you're using PAM, be wary of memory leakages and other bugs in the external PAM library that Dante is forced to use on your platform 😭 not Dante's fault, but you're living with the consequences.
  • bsdauth — this method needs the available client data to be verified by the BSD Authentication system 🌸 Same deal as the username method, except everything gets passed to the BSD authentication system instead. Sibling energy fr.

🌈 ADDRESSES 🌈

Every address field can be one of these things, and honestly? Pick your lane 💫

  • an IP address — and where it's required, you can tack on a netmask, separated from the IP address by a / sign
  • a hostname
  • a domainname — you designate it as a domainname by giving it a leading .
  • an interface name

An IP address can be written in IPv4 form, in IPv6 form, or as the very special value 0/0 👑 which matches all IP addresses — every single one, IPv4 or IPv6, no cap. That special value is intended for rules that should match both IPv4 and IPv6 clients or targets 🦋 so if you've got a rule that needs to catch absolutely everybody, that's your girl.

One lil' exception bestie: every address except the external address can include an optional port specifier ✨

✨ RULES ✨

okay bestie, listen up 💖 there are literally two sets of rules and they work at different levels. The rules prefixed with client get checked first, and they decide if the client is even allowed to connect to the Dante server. We call them "client-rules". They start with client pass if the rule allows the client, or client block if it blocks the client.

It is recommended that the client-rules do not use hostnames, only IP-addresses, both for security and performance reasons. These rules operate at the TCP level. periodt.

The other rules, which we call "socks-rules", are prefixed with socks and operate at the socks protocol level. They start with socks pass for a rule that allows the client, or socks block for a rule that blocks the client.

These rules are only checked if the client connection has already been allowed by the client-rules. The socks-rules are used to evaluate the socks request that the client sends.

While it's less important that these rules use only IP-addresses (provided the client-rules have been configured to only allow access from a pre-defined range of client IP-addresses), it is still recommended. no cap.

Both sets of rules include a pass or deny keyword. The pass/deny keyword determines whether connections matching the rule are to be passed through or be blocked.

Both the client-rules and the socks-rules also specify a from/to address pair which gives the addresses the rule will match.

In both contexts, from refers to the client's address, i.e., the address the client is connecting to the Dante server from. The to address however refers to different things depending on whether it's used in a client-rule or in a socks-rule.

In the client-rule context, to means the address the request is accepted on, i.e., an address the Dante server listens on.

In the socks-rule context, to means the client's destination address, as expressed in the client's socks request. I.e., the address the Dante server should connect to (for TCP sessions) or send packets to (for UDP session) on behalf of the client.

Both sets of rules are evaluated on a "first match is best match" basis. That means the first rule matched for a particular client or socks request is the rule that will be used. iykyk.

In addition to the addresses there is a set of optional keywords which can be given. There are two forms of keywords; conditions and actions. For each rule, all conditions are checked and if they match the request, all actions are executed.

The list of condition keywords is: clientcompatibility, clientmethod, command, from, group, socksmethod, protocol, proxyprotocol, to, user.

The list of action keywords is: bandwidth, libwrap, log, session, redirect, timeout.connect, timeout.negotiate, timeout.io, timeout.tcp_fin_wait, and udp.portrange.

The format and content of the keyword as used in client-rules or socks-rules is identical, but client-rules can contain only a subset of the keyword that socks-rules may contain.

💖 The contents of a client-rule can be 💖

  • bandwidth — The clients matching this rule will all share the given amount of bandwidth, measured in bytes per second. Requires the bandwidth module.
  • clientcompatibility — Enables certain options for compatibility with broken clients. Valid values are: necgssapi, for compatibility with clients implementing GSSAPI the NEC socks way.
  • from — The rule applies to requests coming from the specified address.
  • group — The user must belong to one of the groups given as value.

Note that if gssapi-based authentication is used, the username as provided to the Dante server normally includes the Kerberos domain. The name must be listed on the same form here and in the system groupfile (usually /etc/passwd) if it is to be used.

  • gssapi.enctype — Which encryption to enforce for GSSAPI-authenticated communication. Possible values are clear, integrity, or confidentiality. The default is to accept whatever the client offers except clear, as clear is not part of the SOCKS GSSAPI standard.
  • gssapi.keytab — Value for keytab to use. The default is "FILE:/etc/danted.keytab".
  • gssapi.servicename — Which servicename to use when involving GSSAPI. Default is "rcmd".
  • libwrap — The server will pass the specified parameter line to libwrap for execution.
  • log — Used to control logging. Accepted keywords are connect, disconnect, data, error, ioop, and tcpinfo. The default is no logging.
  • session — Control the max number of sessions or session establishment rate. See below for details.
  • clientmethod — Require that the connection be "authenticated" using one of the given clientmethods.
  • pam.servicename — Which servicename to use when involving pam. Default is "danted".
  • port — Parameter to from, to and via. Accepts the keywords eq/=, neq/!=, ge/>=, le/<=, gt/>, lt/< followed by a number. A port range can also be given as port <start #> - <end #>, which will match all port numbers within the range <start #> and <end #>.

The default is to match all ports.

  • redirect — The source and/or destination can be redirected using the redirect statement. Requires the redirect module.

The syntax of the redirect statement is as follows:

redirect from: ADDRESS

See the redirect manual for detailed information.

  • socksmethod — If the client offers more than one authentication method, Dante will select the method to use based on the order the methods are listed here. Valid values are the same as in the global socksmethod line. Normally there will be no need to set this keyword in a client-rule, but if it is set and the client offers none of the methods listed, the client will be blocked at this stage.
  • timeout.negotiate — See the global timeout.negotiate option.
  • to — The rule applies to requests going to the address given as value.
  • user — The user must match one of the names given as value. If no user value is given for a rule requiring usernames, the effect will be the same as listing every user in the password file.

Note that if gssapi-based authentication is used, the username as provided to the Dante server normally includes the Kerberos domain. The name must be listed on the same form here if it is to be used.

🦋 The contents of a socks-rule can be 🦋

  • bandwidth — The clients matching this rule will all share the given amount of bandwidth, measured in bytes per second. Requires the bandwidth module.
  • bsdauth.stylename — The name of the BSD authentication style to use. The default is to not specify a value, causing the default system style to be used.
  • command — The rule applies to the given commands. Valid commands are bind, bindreply, connect, udpassociate and udpreply. Can be used instead of, or to complement, protocol. The default is all commands valid for the protocols allowed by the rule.
  • from — The rule applies to requests coming from the address given as value.
  • group — The user must belong to one of the groups given as value.
  • libwrap — The server will pass the line to libwrap for execution.
  • log — Used to control logging. Accepted keywords are connect, disconnect, data, ioop, and tcpinfo.
  • session — Control the max number of sessions or session establishment rate. See
  • socksmethod — Require that the connection be established using one of the given authentication methods. A method normally refers to the socks client part of the rule, and thus authenticates the client, and not the target destination (see checkreplyauth for information about authentication the target destination). Valid values are the same as in the global socksmethod line.
  • pam.servicename — What servicename to use when involving pam. Default is "danted".
  • port — Parameter to from, to and via. Accepts the keywords eq/=, neq/!=, ge/>=, le/<=, gt/>, lt/< followed by a number. A portrange can also be given as port <start #> - <end #>, which will match all port numbers within the range <start #> and <end #>.

The default is all ports.

  • protocol — The rule applies to the given protocols. Valid values are tcp and udp. The default is all supported protocols that can apply to the given commands.
  • proxyprotocol — The rule applies to requests using the given proxy protocol. Valid proxy protocols are socks_v4 and socks_v5. The default is all supported proxy protocols.
  • redirect — The source and/or destination can be redirected using the redirect statement. Requires the redirect module.

The syntax of the redirect statement is as follows:

redirect from: ADDRESS

redirect to: ADDRESS

The semantics of from and to vary according to command. See the redirect manual for detailed information.

  • timeout.connect — See the global timeout.connect option.
  • timeout.io — See the global timeout.io option.
  • timeout.tcp_fin_wait — See the global timeout.tcp_fin_wait option.
  • to — The rule applies to requests going to or using the address given as value. Note that the meaning of this address is affected by command.
  • udp.portrange — The argument to this keyword is two port numbers, separated by a dash (-). They specify the UDP port-range that will be used between the socks-client and the Dante-server for UDP packets. Note that this has no relation to the UDP port-range used between the Dante-server and external, non-socks, clients/servers.
  • user — The user must match one of the names given as value. If no user value is given for a rule requiring usernames, the effect will be the same as listing every user in the password file.

🌸 SESSION 🌸

okay bestie so the session keyword is a lil glow-up you can slap onto any rule to cap how many sessions are vibing at once and how fast new ones are allowed to show up. There are two main commands running this whole operation:

  • session.max — controls the max number of sessions that can be matched 💅
  • session.throttle — controls the connection rate ⏱️

These can be applied as the total limit for all matching clients, and they can be set as global defaults, or dropped into any of the rule types. So flexible, so iconic.

session.max takes a number as its argument — that number is the highest count of simultaneous connections you're allowing. Periodt.

session.throttle takes two numbers separated by a slash character: the first is the number of connections, the second is a time duration in seconds. If more than the specified number of connections come through in the specified number of seconds, the extra connections get dropped. Bye 👋

🦋 Stateful tracking (the fancy part) 🦋

Stateful session tracking on a per IP-address basis is also supported, bestie. With stateful tracking, the limits apply to each connection with a matching IP-address, and the session.state.key keyword is what controls how that IP-address gets determined. Right now two values are supported:

  • from — the limit applies to all hosts with the same source IP-address
  • hostid — the limit applies to all TCP connections with the same hostid value

If a hostid value is used, you can also bring in session.state.key.hostindex to choose which of the two hostid values gets used — the first value is the default. ✨

👑 How limits get evaluated 👑

Limits are evaluated in this order, no cap:

  1. client rules
  2. hostid rules
  3. socks rules

By default, a limit set in a matching client rule will be used also by any subsequent matching hostid or socks rules — unless either of those rules also has session limit keywords of their own. That's the session inheritance situation, iykyk.

You can disable that inheritance in client and hostid rules, which makes them only apply in the rule where they appear. How? Set session.inheritable to no. Simple as.

🚨 real talk: the session keywords must be set in a rule (either client, hostid, or socks). Setting them globally is not supported. Don't try it, bestie.

🌈 TRAFFIC MONITORING 🌈

The Dante server can be configured to monitor the traffic passing through it, and to trigger alarms based on the observed network traffic. It's giving surveillance but make it ✨helpful✨.

The alarms live in so-called monitors. These objects have the same general format as the rules Dante uses for access control, and they let you passively monitor network traffic — or the lack of network traffic. Which is honestly the more dramatic option. 💀

Here's the general monitor syntax, showing a monitor with no monitoring operations at all:

         monitor {
          from: 0.0.0.0/0 to: www.example.org port = 80
          protocol: tcp
         }

A monitor can include many of the same keywords available in the Dante ACL rules. Currently supported subset:

  • from — normally specifies what SOCKS client addresses/networks to monitor
  • to — normally specifies what target addresses/networks to monitor
  • protocol — restricts monitoring to a certain protocol (TCP, UDP or both). Note: only TCP should be used for now
  • hostid — restricts monitoring to only clients with a specific hostid value set
  • hostindex — used along with the hostid keyword to control which of the two possible hostid values will be used when matching
⚠️ NOTE: it is currently recommended that the protocol keyword is always specified and set to tcp, because there is currently only limited support for monitoring of UDP traffic, and testing of UDP traffic monitoring has not been done. 🫶

The main function of monitors is to be a container for one or more alarms, which are specified using a whole new set of keywords that aren't available for other rules. Alarms specify a condition that will make Dante log a warning if the condition is triggered. 🔔

Active TCP sessions will at most match one monitor, but multiple alarms can be specified inside a single monitor. That means you can set up multiple sets of conditions for the same TCP sessions, depending on what network interface the traffic is transferred on and whether the traffic is being received or transmitted. Versatile queen. 👑

Alarms can trigger because of periods of no data or little data being transmitted, or a large number of TCP connections disconnecting during a short period of time, or for other reasons. Full list of triggerable conditions is below. ⬇️

🎀 Data alarms 🎀

Adding an alarm.data keyword to a monitor means warnings get logged if there are periods with too little network traffic. 🥺

Dante has four network paths and data alarms can be configured independently for each of them:

  • internal.alarm.data.recv — data received on Dante's internal interface (data sent from the SOCKS clients to Dante)
  • internal.alarm.data.send — data sent out on Dante's internal interface (data sent from Dante to the SOCKS clients)
  • external.alarm.data.recv — data received on Dante's external interface (data sent from the target servers to Dante)
  • external.alarm.data.send — data sent out on Dante's external interface (data sent from Dante to the target servers)

The data.alarm keyword takes two parameters: a byte count and a duration in seconds. The alarm triggers if the specified number of seconds pass with only the specified number of bytes (or less) being transmitted. So like… nothing happened, and that's the problem. 😭

The syntax is:

internal.alarm.data.recv: DATALIMIT in INTERVAL

The DATALIMIT is a number specifying the byte limit. The INTERVAL is a number specifying the duration. If only DATALIMIT bytes (or less) have been transferred during a period of INTERVAL seconds, an alarm triggers in Dante. 🚨

Data alarms trigger when a period of data idleness has been detected. Once a data alarm has triggered, it remains active until it is cleared. A warning gets logged when the alarm triggers, and then again when the alarm condition is cleared. In between those two points, no warnings related to this alarm get logged — this avoids repeating the same alarm/warning a million times during network problems that last for an extended amount of time. Very considerate of it, honestly. When the alarm is cleared, Dante also includes info about how long the alarm condition lasted. ⏳

A data alarm can be cleared in two ways:

  1. automatically — once enough data has been transferred in a short enough amount of time
  2. manually — by sending the Dante server a SIGHUP signal

A SIGHUP will cause all active alarms to be cleared. And no log messages indicating that the alarms have cleared will be logged when alarms are cleared this way. Silent slay. 🤫

Once an alarm has been cleared, it can trigger again if enough data isn't being transferred.

💀 Note: data alarms will trigger regardless of whether there are active sessions matching the monitor or not; if enough data is not being transmitted or received, a data alarm will trigger. Alarms will trigger also shortly after server startup, if the Dante server does not receive sufficient traffic to prevent the alarms from triggering.
💀 Note: the message indicating that an alarm has cleared is not logged if the alarm was cleared due to a SIGHUP signal being received.

💅 Disconnect alarms 💅

Disconnect alarms are all about connection disconnects, and by using the alarm.disconnect keyword the Dante server can log warnings based on the number and rate of terminated connections. Oof, the drama of it all. 🍓

There are two variants of the alarm keyword — one for the internal network interface (between the SOCKS clients and Dante), and one for the external interface (between the Dante server and the target servers):

  • internal.alarm.disconnect — connections between SOCKS clients and the Dante server
  • external.alarm.disconnect — connections between the Dante server and target servers

Each alarm keyword takes three parameters: a minimum count, a ratio value, and a time interval. The format is:

internal.alarm.disconnect: MINCOUNT/RATIO in INTERVAL

  • The MINCOUNT is the minimum number of connections that must be disconnected for the alarm to trigger.
  • The RATIO is used together with the MINCOUNT to express the number of connections, relative to the total number of connections that have existed in the time period, that must be disconnected for the alarm to trigger.
  • The INTERVAL is the time in seconds within which the disconnects must occur for the alarm to trigger.

To set values that are actually useful, you need some knowledge about the expected amount of network traffic and number of sessions. If the rate of disconnects, as a percentage, is lower than the ratio specified, an alarm will not trigger. Conversely, if the MINCOUNT is set too low, alarms might trigger too frequently — because only a small number of disconnects might be sufficient to achieve the required number of disconnects and disconnect ratio at times when there are only a few active sessions. Tuning matters, bestie. 🎯

Only connections that are terminated on the specified interface are counted. Like, an external.alarm.disconnect alarm will only trigger for connections terminated on the network interface between the Dante server and the target server — either by the target server closing the connection to Dante, or by Dante receiving a fatal network error from that side of the connection (e.g., a TCP RST packet).

Connections that are closed on the internal interface (by the SOCKS clients) will not count towards a disconnect alarm on the external side. Likewise, connections closed by target servers will not count towards a disconnect alarm on the internal side.

A practical consequence of this: if a large number of connections are simultaneously closed by both the client and the target server, each connection will only be counted as a disconnect on one of the sides — either the external side or the internal side, depending on which side closes the connection first. First one to leave wins, I guess. 🙈

Alarms trigger each time a sufficient number of disconnects occur. Each sufficiently large burst of disconnects will result in an alarm, but normally at most one warning per alarm will be logged during each time interval — though this might change in a later version of Dante. 👀

Separate alarms are produced for each distinct alarm keyword when multiple alarms are specified in a monitor rule. ✨

🛣️ ROUTES

okay so routes get set up with a route keyword, and then inside a lil pair of curly braces ({}) you get a whole set of keywords that control how that route behaves. bestie, check dante.conf(5) for the full rundown — this is what makes server-chaining happen, where one socks-server connects to another socks-server further upstream. it's giving relay race. 🏃‍♀️💨

The syntax for these routes is the same as the routes used by the client. so yeah, go peek at dante.conf(5) for all the route syntax tea.

But there are some special things you need to be aware of regarding serverchaining and routes specified for the server, and honestly some of these are 🚨 important 🚨:

  • At present serverchaining is only supported for the tcp connect command. that's it. that's the list. 💀
  • If the route specifies that a username/password-method should be offered to the upstream proxy, Dante will forward the username/password received from its own client to the foreign upstream proxy, meaning the upstream proxy will receive the user's username and password in cleartext from Dante. 😭 cleartext!! like, the whole password, just vibing out there unprotected. be so serious about this one.
  • At present serverchaining does not scale well in Dante and should not be used for anything but minimal client loads. so like, keep it cute and small. this is not your main character load balancer. 🙈

📚 EXAMPLES

See the example/ directory in the distribution. that's where the good stuff lives, go look. ✨

🗂️ FILES

  • /etc/danted.conf — Dante server configuration file. the whole point of this page fr.
  • /etc/passwd — systemfile used when doing standard username/password authentication.

👑 AUTHORS

For inferno Nettverk A/S:

  • Michael Shuldman
  • Karl-Andre' Skevik

the legends themselves, we stan. 🫶

🔗 SEE ALSO

Information about new releases and other related issues can be found on the Dante WWW home page: http://www.inet.no/dante/

Information about commercial support can be found on the Dante WWW support page: http://www.inet.no/dante/support.html

okay bestie that's a wrap on the whole page!! 💖 this one's DANTED.CONF(5), dated July 29 2013 — yes she's an icon from 2013 and she still ate, no cap. go configure something slay, and remember: cleartext passwords are NOT the vibe. periodt. 💅✨🌸

📦 where this page comes from