Why is SNMP broken?
Ubuntu Version: Ubuntu 14.04.1 LTS
SNMP Version: 5.7.2
Short Issue: A lot of the entries in the "default" configuration file are broken. Which doesn't really matter because I can't even get SNMP started.
Desired Outcome: I want a working SNMP instance, one with as many of the defaults functional in it as possible.
NOTE: From a great many sources, including Canonical owned Ubuntu websites, it is said that I have to modify export and SNMPDOPTS, in order to have basic functionality.
/etc/default/snmpd
export MIBS=UCD-SNMP-MIB
SNMPDRUN=yes
SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -g snmp -I -smux -p /var/run/snmpd.pid -c /etc/snmp/snmpd.conf'
TRAPDRUN=no
TRAPDOPTS='-Lsd -p /var/run/snmptrapd.pid'
SNMPDCOMPAT=yes
/etc/snmp/snmpd.conf
view systemonly included .1.3.6.1.2.1.1
view systemonly included .1.3.6.1.2.1.25.1
rocommunity public
rwcommunity nanana
sysLocation vm1-ryd-wlo
sysContact Paul Adams <[email protected]>
sysServices 72
disk / 10000
disk /var 5%
load 12 10 5
trapsink localhost public
iquerySecName internalUser
rouser internalUser
master agentx
/var/log/syslog
Oct 3 13:59:51 mdnsreflector-ryd-wlo snmpd[9120]: Server Exiting with code 1
Oct 3 14:00:09 mdnsreflector-ryd-wlo snmpd[9143]: Turning on AgentX master support.
Oct 3 14:00:09 mdnsreflector-ryd-wlo snmpd[9145]: NET-SNMP version 5.7.2
sudo service --status-all
[ + ] snmpd
sudo service ufw status
Status: inactive
Even though this configuration loads and is apparently running. You can't actually query anything from this SNMP instance from a remote device. The connection ultimately times out.
Querying it from the server itself yields nothing.
snmpwalk -Os -c public -v 1 localhost system
system: Unknown Object Identifier (Sub-id not found: (top) -> system)
- I had to remove the "agentAddress" entries because the software kept panicking every time it attempted to process that command. (Even though that is the default and the way it supposed to be listed in the configuration.)
/etc/var/syslog
Oct 3 14:10:32 mdnsreflector-ryd-wlo snmpd[9292]: Turning on AgentX master support.
Oct 3 14:10:32 mdnsreflector-ryd-wlo snmpd[9292]: Turning on AgentX master support.
Oct 3 14:10:32 mdnsreflector-ryd-wlo snmpd[9292]: Error opening specified endpoint "udp:161"
Oct 3 14:10:32 mdnsreflector-ryd-wlo snmpd[9292]: Server Exiting with code 1
sudo service --status-all
[ - ] snmpd
- I had to remove several of the default entries in the config because they also caused errors upon running them.
/etc/snmp/snmpd.conf
proc mount
proc ntalkd 4
proc sendmail 10 1
includeAllDisks 10%
extend test1 /bin/echo Hello, world!
extend-sh test2 echo Hello, world! ; echo Hi there ; exit 35
/var/log/syslog
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 90: Error: Already have an entry for this process.
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 92: Error: Already have an entry for this process.
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 94: Error: Already have an entry for this process.
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 106: Error: includeAllDisks already specified.
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 106: Error: #011ignoring: includeAllDisks 10%
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 146: Error: duplicate trigger name
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: message repeated 6 times: [ /etc/snmp/snmpd.conf: line 146: Error: duplicate trigger name]
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 148: Error: duplicate trigger name
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: /etc/snmp/snmpd.conf: line 148: Error: duplicate trigger name
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: duplicate table data attempted to be entered. row exists
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: Failed to register extend entry 'test1' - possibly duplicate name.
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: duplicate table data attempted to be entered. row exists
Oct 3 10:51:11 mdnsreflector-ryd-wlo snmpd[7575]: Failed to register extend entry 'test2' - possibly duplicate name.
Solution 1:
SNMP is not broken. The process to get it working is just a bit convoluted.
The following steps have been verified to work on 14.04:
After installing SNMP and its daemon(sudo apt-get install snmp snmpd), you will need to edit the file /etc/snmp/snmp.conf and comment out the line containing "mibs:"
Within this file, change the line:
mibs :
to
#mibs :
Next, assuming you haven't done this already, you will need to obtain the full set of IETF MIBs. These files do not ship, by default, on Debian/Ubuntu systems due to licensing issues.
From the terminal(Ctrl-Alt-t), enter the following commands:
sudo apt-get install snmp-mibs-downloader
sudo download-mibs
Then, you will need to modify /etc/snmp/snmpd.conf.
-
To allow SNMP the system to receive queries on interfaces other than its loopback address. The lines for this should look like this:
# Listen for connections from the local system only # agentAddress udp:127.0.0.1:161 # Listen for connections on all interfaces (both IPv4 *and* IPv6) agentAddress udp:161,udp6:[::1]:161Note that this will allow ANY system to query your machine. You will need to adjust this to limit SNMP access to your device.
-
You will now want to change your Read-only SNMP string from
publicto a custom string of your choosing, as below:#rocommunity public default -V systemonly rocommunity <My$ecret$tr1nG> (don't use this example!)Note: Removing
-V systemonlyfrom the line will allow access to the entire MIB tree and not restrict it to the system part of the tree. -
Restart the SNMP daemon
sudo service snmpd restart
Finally, your SNMP query should now respond properly.
e.g.:
snmpwalk -v 2c -c <My$ecret$tr1nG> <MachineName> ipadd
IP-MIB::ipAdEntAddr.127.0.0.1 = IpAddress: 127.0.0.1
IP-MIB::ipAdEntAddr.192.168.1.7 = IpAddress: 192.168.1.7
IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1
IP-MIB::ipAdEntIfIndex.192.168.1.7 = INTEGER: 2
IP-MIB::ipAdEntNetMask.127.0.0.1 = IpAddress: 255.0.0.0
IP-MIB::ipAdEntNetMask.192.168.1.7 = IpAddress: 255.255.255.0
IP-MIB::ipAdEntBcastAddr.127.0.0.1 = INTEGER: 0
IP-MIB::ipAdEntBcastAddr.192.168.1.7 = INTEGER: 1
See the following answers for additional reference:
How to get or configure IP-MIB in Ubuntu 12.04?
What is SNMP?