snmposter

SNMP Agent Simulator

This tool allows you to take the output of an snmpwalk command and then pretend to be the agent that it was gathered from. This can be useful when you're developing SNMP management tools.

Requirements

Twisted, TwistedSNMP, PySNMP-SE and Tornado Web Server.

Twisted is available from PyPI and will be automatically installed if you go the route of easy_install or pip. TwistedSNMP and PySNMP-SE are not currently available from PyPI and should be individually downloaded from sourceforge and installed from source.

Installation

Follow the basic guidelines to use snmposter on CentOS.

https://github.com/cluther/snmposter

Ubuntu 14.04

1. Install Python development tools.

   $ sudo apt-get install gcc python-dev python-setuptools python-tornado git-core

2. Install TwistedSNMP dependency.

   $ wget http://downloads.sourceforge.net/project/twistedsnmp/twistedsnmp/0.3.13/TwistedSNMP-0.3.13.tar.gz
   $ tar -xzf TwistedSNMP-0.3.13.tar.gz
   $ cd TwistedSNMP-0.3.13
   $ sudo python setup.py install
   $ cd ..

3. Install PySNMP-SE dependency.

   $ wget http://downloads.sourceforge.net/project/twistedsnmp/pysnmp-se/3.5.2/pysnmp-se-3.5.2.tar.gz
   $ tar -xzf pysnmp-se-3.5.2.tar.gz
   $ cd pysnmp-se-3.5.2
   $ sudo python setup.py install
   $ cd ..

4. Install my snmposter.

   $ git clone https://github.com/netbuffalo/snmposter.git
   $ cd snmposter
   $ sudo python setup.py install
   $ cd ..

Basic Usage

Installing will create a command line tool called snmposter. This tool requires root access because it listens on 161/udp and creates loopback aliases to support emulating multiple SNMP agents simultaneously.

The snmposter command takes a single command line argument: -f or --file. The file passed to this option must contain one or more rows with two columns each. The first column should be the absolute or relative path to a file containing the output of an snmpwalk command. The second column should contain an IP address that this snmpwalk data will be exposed on.

Example usage:

$ sudo snmposter -f /path/to/agents.csv

Example contents of /etc/snmposter/agents.csv:

/path/to/Cisco_2811.snmpwalk,127.0.1.11
/path/to/NetApp_Filer_FAS3020.snmpwalk,127.0.1.12

This example usage will cause snmposter to run in the background, create two new IP aliases on the loopback interface (127.0.1.11 and 127.0.1.12), and expose the contents of each snmpwalk file as an SNMP agent on UDP port 161 of the appropriate IP address. If you're going to be using this frequently I would recommend adding some entries to your /etc/hosts file to make it even easier.

Example additions to /etc/hosts:

127.0.1.11      cisco-2811
127.0.1.12      netapp-filer-fa3020

Important Note: The snmpwalk output file that snmposter consumes must be generated with very specific snmpwalk command line options. These options allow snmposter to get the most raw data possible and provides the most accurate simulation.

Example snmpwalk command to generate the above Cisco_2811.snmpwalk file:

# SNMPv1
$ snmpwalk -v1 -c public -OxbenU cisco2811-address .1 > Cisco_2811.snmpwalk

# SNMPv2c
$ snmpbulkwalk -v2c -c public -OxbenU cisco2811-address .1 > Cisco_2811.snmpwalk

$ head Cisco_2811.snmpwalk
.1.3.6.1.2.1.1.1.0 = STRING: "Cisco Internetwork Operating System Software IOS (tm)..."
.1.3.6.1.2.1.1.2.0 = OID: .1.3.6.1.4.1.9.1.317
.1.3.6.1.2.1.1.3.0 = Timeticks: (880537345) 101 days, 21:56:13.45
.1.3.6.1.2.1.1.4.0 = STRING: "netbuffalo"
.1.3.6.1.2.1.1.5.0 = ""
.1.3.6.1.2.1.1.6.0 = ""
.1.3.6.1.2.1.1.7.0 = INTEGER: 12
.1.3.6.1.2.1.2.1.0 = INTEGER: 5746
.1.3.6.1.2.1.2.2.1.1.1 = INTEGER: 1
.1.3.6.1.2.1.2.2.1.1.2 = INTEGER: 2

The important command line options are -m none -O enU to get the raw output and '-C c' to ignore out of sequence responses from the switch. (Sometimes this validation error is triggered when walking routing MIBS on some switches)

Don't worry if you get an error like Cannot find module (none): At line 0 in (none) as this is expected and a result of us trying to load a non-existent MIB.

WebAPI Usage

# start snmposter (WebAPI port: 8888).
$ sudo snmposter -f agents.csv -w 8888

# update mib objects.
$ curl -v -H "Content-type: application/json" -X POST --data @/path/to/data.json \
  http://snmposter-host:8888/mib/oper/update

# json format.
$ cat /path/to/data.json
{
"127.0.1.11": [ # agent address.
# {OID, Data Type, Object Value}
{ "oid":".1.3.6.1.2.1.1.1.0" , "type":"STRING", "value":"UPDATED DESCRIPTION." },
{ "oid":".1.3.6.1.2.1.1.3.0" , "type":"Timeticks", "value":"0" }
]
}

# updated?
$ snmpget -v1 -c public 127.0.1.11 .1.3.6.1.2.1.1.1.0
iso.3.6.1.2.1.1.1.0 = STRING: "UPDATED DESCRIPTION."

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