Unable to retrieve Squid OID information for monitoring proxy

Question

I installed Squid and snmp on my CentOS 7 virtual machine and now I would like to monitor the proxy server using snmp. The problem is that I cannot retrieve (by the snmpwalk command) any of the available Squid OID under the 1.3.6.1.4.1.3495 parent tree. See this link for the entire collection: Squid Wiki

For instance, if I prompt the command:

snmpwalk -v 1 -c public <machine_ip>:3401 .1.3.5.1.4.1.3495.1.1.2.0

which is supposed to retrieve the cacheSysStorage, I get a "NO Response" error. I even tried the following alternative prompts:

snmpwalk -v 1 -c public <machine_ip> OID_number

snmpwalk -v 1 -c public localhost:3401 OID_number

So with or without the 3401 port, it does not matter: it always results with a timeout error. Looking at the snmpd.conf file, I saw that another OID tree is getting some system information, so I prompted the following:

snmpwalk -v 1 -c public <machine_ip> .1.3.6.1.4.1.2021.100

I get a positive response! But it is not the OID tree needed for monitoring the Squid proxy server.

FYI, I edited the snmpd.conf file with the following:

proxy -v 1 -c public <machine_ip>:3401 .1.3.6.1.4.1.3495.1

and I double checked that the public zone in FirewallD service has the port UDP 3401 allowed. I think to have tried any possible action but I am still unable to test OID information retrievement.

Could you suggest me anything to check or modify? Thank you.

Answer 1

Ok, it looks like an incorrect configuration setting of the squid.conf file. For anyone in the future would come here...

I setup the access control properties by using Webmin (Servers > Squid proxy server > Proxy restrictions): I had allowed the snmp_community called public (which is the one I use) but this created a http_access allow rule in the configuration file instead a snmp_access, as written here: http://etutorials.org/Server+Administration/Squid.+The+definitive+guide/Chapter+14.+Monitoring+Squid/14.3+Using+SNMP/

Now I am getting the information correctly. Thank you.