Forum Discussion

wilcdr's avatar
wilcdr
Icon for Nimbostratus rankNimbostratus
Oct 18, 2016

Making SNMP queries in iRules

From other questions people have asked, it looks like there is no built-in command for SNMP queries that you can make from iRules. Is that still true (running LTM 11.6)?   If that is not possible...
application delivery
BIG-IP
devops
iRules
  • Kai_Wilke's avatar
    Kai_Wilke
    Feb 08, 2023

    Running an periodic iCall Job in the Config-Plane to query SNMP and write results to a DG would be a much easier and elegant alternative. No? Dealing with ASN1-BER in iRules isn't much fun... 🙂

    Cheers, Kai

    LiefZimmerman : Good to see that the ordering in DevCentral has finally been changed, so that we can see if something gets added to rather old questions. Thanks!

VernonWells's avatar
VernonWells
Icon for Employee rankEmployee
Oct 19, 2016

Actually, with SNMP, unless everything is correct (including the community for v1/v2c or the auth credentials for v3), then the remote end usually does not respond. A good way to test is to use 

tcpdump
on the BIG-IP and open the capture in Wireshark. Usually, the dissector will catch errors. This will also tell you if the remote end is sending anything back.

Incidentally, when using a sideband connection, it is always best to go through a Virtual Server, rather than sending traffic directly. Virtual Servers provide much better control. Simply create an internal VS with a pool containing your target, and set the protocol to UDP.