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snmptest

If you need to query a device that supports the Simple Network Management Protocol (SNMP), you can do so from a command line interface, i.e, a shell prompt, on a Mac OS X or Linux system using the snmptest tool. To use the utility, issue the snmptest command specifying the "community string", which is somewhat equivalent to a password, with the -c option, specify the version of SNMP with the -v option and then specify the IP address or fully qualified domain name (FQDN). You will get a "Variable:" prompt when you run the command. You can specify an object identifider (OID) that you wish to query at that prompt. If you hit Enter the prompt will be repeated. When you've finished entering variables you wish to query, hit Enter at the next "Variable" prompt without entering any variable. You should then see the results returned as shown below. You can hit Ctrl-C to terminate the program.

# snmptest -c SomeSecret0123 -v 1 192.168.0.11
Variable: system.sysLocation.0
Variable: system.sysContact.0
Variable:
Received Get Response from UDP: [192.168.0.11]:161->[0.0.0.0]:41231
requestid 0xAF07FC2 errstat 0x0 errindex 0x0
SNMPv2-MIB::sysLocation.0 = STRING: London
SNMPv2-MIB::sysContact.0 = STRING: John Doe
Variable: ^C
#

[ More Info ]

[/network/snmp] permanent link

Get ARP Table

I needed to be able to get the ARP table from Cisco devices, so I created get_arp, a Perl script which will query a router, switch, etc. via SNMP and obtain the ARP table from the device. There are two mandatory arguments for the script, the hostname or IP address for the device and the read-only community string for the device. If given only those two arguments, the script will produce output similar to what is shown below:

% ./get_arp 192.168.220.76 tViSoN1a
ARP table for 192.168.220.76 on Wed Feb  1 22:21:38 2006

192.168.220.65 = 0:30:f2:ec:17:fc
192.168.220.66 = 0:30:f2:ec:8b:fc
192.168.220.67 = 0:30:f2:ec:17:ff
192.168.220.68 = 0:30:f2:ec:8b:ff
192.168.220.69 = 0:90:b1:81:e9:0
192.168.220.70 = 0:60:3e:7e:c7:40
192.168.220.75 = 0:9:b7:7d:e6:0
192.168.220.76 = 0:60:3e:7e:1e:a0
192.168.220.77 = 0:f:f7:5b:b:0
192.168.220.78 = 0:f:f7:5d:64:f0

An optional argument "--nomac" will cause the script to only display the IP addresses in the ARP table, not the MAC addresses associated with the IP addresses as shown below:

% ./get_arp --nomac 192.168.220.76 tViSoN1a
ARP table for 192.168.220.76 on Wed Feb  1 22:21:49 2006

192.168.220.65
192.168.220.66
192.168.220.67
192.168.220.68
192.168.220.69
192.168.220.70
192.168.220.75
192.168.220.76
192.168.220.77
192.168.220.78

To use the script, download the script and use chmod 744 to make the script executable by the owner. Modify the first line, if Perl is located somewhere else on your system, which you can determine by the command which perl. The script relies on the snmpwalk utility, which is available from http://www.net-snmp.org/. You can determine if it is available on your system already by issuing the command which snmpwalk.

[/network/snmp] permanent link

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Thu, Oct 14, 2010 7:44 pm

Wed, Feb 01, 2006 6:49 pm