I was recently testing Zenoss on a CentOS 5 system when I discovered that the snmpd component of net-snmp would not start. There were no error messages in /var/log/snmpd.log so this made diagnosis a bit tricky given I had never used the tool before. :-)

Running the daemon manually with snmpd -f showed the following error:

snmpd: symbol lookup error: snmpd: undefined symbol: smux_snmp_select_list_get_length

A quick Google search found the following bug based upon that error: http://bugs.centos.org/view.php?id=2700

This bug indicates that the net-snmp-libs package was not being updated when the net-snmp package was updated using CentOS's built-in update manager. A quick check validated this:

[root@cgibbons-dev CentOS]# rpm --query net-snmp
net-snmp-5.3.1-19.el5_1.4
[root@cgibbons-dev CentOS]# rpm --query net-snmp-libs
net-snmp-libs-5.3.1-14.el5

And then a quick update of the net-snmp-libs package solved the issue:

[root@cgibbons-dev ~]# yum update net-snmp-libs
Loading "installonlyn" plugin
Setting up Update Process
Setting up repositories
base                      100% |=========================| 1.1 kB    00:00     
updates                   100% |=========================|  951 B    00:00     
addons                    100% |=========================|  951 B    00:00     
extras                    100% |=========================| 1.1 kB    00:00     
Reading repository metadata in from local files
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for net-snmp-libs to pack into transaction set.
net-snmp-libs-5.3.1-19.el 100% |=========================|  27 kB    00:00     
---
\> Package net-snmp-libs.i386 1:5.3.1-19.el5\_1.4 set to be updated --\> Running transaction check Dependencies Resolved ============================================================================= Package Arch Version Repository Size ============================================================================= Updating: net-snmp-libs i386 1:5.3.1-19.el5\_1.4 updates 1.2 M Transaction Summary ============================================================================= Install 0 Package(s) Update 1 Package(s) Remove 0 Package(s) Total download size: 1.2 M Is this ok [y/N]: Y Downloading Packages: (1/1): net-snmp-libs-5.3. 100% |=========================| 1.2 MB 00:00 Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Updating : net-snmp-libs ######################### [1/2] Cleanup : net-snmp-libs ######################### [2/2] Updated: net-snmp-libs.i386 1:5.3.1-19.el5\_1.4 Complete!