Smokeping_prob...TMonTcpConnect(3)

📦
version 2.9.0 · 12 versions
, in alpine 3.23, alpine 3.24

🌸 NAME 🌸

okay bestie, welcome to the manual page for Smokeping_prob...TMonTcpConnect(3) from SmokePing. The probe itself is Smokeping::probes::CiscoRTTMonTcpConnect — literally a probe for SmokePing. 💅

✨ SYNOPSIS ✨

copy-paste config energy, no cap:

 *** Probes ***

 +CiscoRTTMonTcpConnect

 forks = 5
 offset = 50%
 step = 300
 timeout = 15

 # The following variables can be overridden in each target section
 /^influx_.+/ = influx_location = In the basement
 ioshost = RTTcommunity@Myrouter.foobar.com.au # mandatory
 iosint = 10.33.22.11
 pings = 5
 port = 80
 timeout = 15
 tos = 160

 # [...]

 *** Targets ***

 probe = CiscoRTTMonTcpConnect # if this should be the default probe

 # [...]

 + mytarget
 # probe = CiscoRTTMonTcpConnect # if the default probe is something else
 host = my.host
 /^influx_.+/ = influx_location = In the basement
 ioshost = RTTcommunity@Myrouter.foobar.com.au # mandatory
 iosint = 10.33.22.11
 pings = 5
 port = 80
 timeout = 15
 tos = 160

🦋 DESCRIPTION 🦋

okay so picture this: this probe uses the ciscoRttMon MIB functionality (aka “Service Assurance Agent”, “SAA”) of Cisco IOS to measure TCP connect times between a Cisco router and a TCP server. The measured value is the time to establish a TCP session — iykyk, it’s the time between the router’s initial SYN TCP packet and the host’s SYN ACK packet. The router terminates the TCP session immediately after the reception of SYN ACK with a FIN packet. iconic behavior, honestly. 🔥

🧚 VARIABLES 🧚

💖 Supported probe-specific variables

  • forks — run this many concurrent processes at maximum. Example value: 5. Default value: 5.
  • offset — if you run many probes concurrently you may want to prevent them from hitting your network all at the same time. Using the probe-specific offset parameter you can change the point in time when each probe will be run. Offset is specified in % of total interval, or alternatively as 'random', and the offset from the 'General' section is used if nothing is specified here. Note that this does NOT influence the rrds itself, it is just a matter of when data acquisition is initiated. (This variable is only applicable if the variable 'concurrentprobes' is set in the 'General' section.) Example value: 50%.
  • step — duration of the base interval that this probe should use, if different from the one specified in the 'Database' section. Note that the step in the RRD files is fixed when they are originally generated, and if you change the step parameter afterwards, you’ll have to delete the old RRD files or somehow convert them. (This variable is only applicable if the variable 'concurrentprobes' is set in the 'General' section.) Example value: 300.
  • timeout — how long a single 'ping' takes at maximum. Example value: 15. Default value: 5.

🎀 Supported target-specific variables

  • /^influx_.+/ — this is a tag that will be sent to influxdb and has no impact on the probe measurement. The tag name will be sent without the influx_ prefix, which will be replaced with tag_ instead. Tags can be used for filtering. Example value: influx_location = In the basement.
  • ioshost — the (mandatory) ioshost parameter specifies the Cisco router, which will establish the TCP connections as well as the SNMP community string on the router. Example value: RTTcommunity@Myrouter.foobar.com.au. This setting is mandatory. 🚨
  • iosint — the (optional) iosint parameter is the source address for the TCP connections. This should be one of the active (!) IP addresses of the router to get results. IOS looks up the target host address in the forwarding table and then uses the interface(s) listed there to send the TCP packets. By default IOS uses the (primary) IP address on the sending interface as source address for a connection. Example value: 10.33.22.11.
  • pings — how many pings should be sent to each target, if different from the global value specified in the Database section. Note that the number of pings in the RRD files is fixed when they are originally generated, and if you change this parameter afterwards, you’ll have to delete the old RRD files or somehow convert them. Example value: 5.
  • port — the (optional) port parameter lets you configure the destination TCP port on the host. The default is the http port 80. Default value: 80.
  • timeout — how long a single RTTMon TcpConnect 'ping' takes at maximum plus 10 seconds to spare. Since we control our own timeout the only purpose of this is to not have us killed by the ping method from basefork. Example value: 15. Default value: 15.
  • tos — the (optional) tos parameter specifies the value of the ToS byte in the IP header of the packets from the router. Multiply DSCP values times 4 and Precedence values times 32 to calculate the ToS values to configure, e.g. ToS 160 corresponds to a DSCP value 40 and a Precedence value of 5. Please note that this will not influence the ToS value in the packets sent by the host. Example value: 160. Default value: 0.

👑 AUTHORS 👑

shoutout to Joerg.Kummer at Roche.com — main character energy. 💜

🌈 NOTES 🌈

🍓 IOS VERSIONS

This probe only works with Cisco IOS 12.0(3)T or higher. It is recommended to test it on less critical routers first. fr fr, don’t YOLO it on your most important router.

🦋 INSTALLATION

To install this probe copy ciscoRttMonMIB.pm to ($SMOKEPINGINSTALLDIR)/Smokeping/lib and CiscoRTTMonTcpConnect.pm to ($SMOKEPINGINSTALLDIR)/lib/Smokeping/probes. V0.97 or higher of Simon Leinen’s SNMP_Session.pm is required.

The router(s) must be configured to allow read/write SNMP access. Sufficient is:

snmp-server community RTTCommunity RW

If you want to be a bit more restrictive with SNMP write access to the router, then consider configuring something like this:

access-list 2 permit 10.37.3.5
snmp-server view RttMon ciscoRttMonMIB included
snmp-server community RTTCommunity view RttMon RW 2

The above configuration grants SNMP read-write only to 10.37.3.5 (the smokeping host) and only to the ciscoRttMon MIB tree. The probe does not need access to SNMP variables outside the RttMon tree. locked down and slaying. 🔐✨

💀 BUGS 💀

ngl, there’s a known quirk: the probe establishes unnecessary connections, i.e. more than configured in the "pings" variable, because the RTTMon MIB only allows to set a total time for all connections in one measurement run (one "life"). Currently the probe sets the life duration to "pings"*5+3 seconds (5 secs is the timeout value hardcoded into this probe). it’s giving “the MIB said no” energy, honestly. 😭

🦋 SEE ALSO 🦋

The best source for background info on SAA is Cisco’s documentation on http://www.cisco.com and the CISCO-RTTMON-MIB documentation, which is available at: ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RTTMON-MIB.my

that’s the whole vibe, bestie — SmokePing source/version 2.9.0, dated 2025-06-30. now go measure those TCP connects and slay. 💖✨

📦 where this page comes from