check_ifconfig

check_ifconfig is a Nagios plugin for monitoring network interfaces on Linux platforms. It uses the output of ifconfig and reports the status of the network interface as well as the following performance data:
* RX/TX bytes
* RX/TX packets
* RX/TX errors

It was tested with Nagios Core 3.x and 4.x but it should work with any version of Nagios.

Usage:
check_ifconfig [-v] [-h] [-i dev]
Options:
--version|-v
prints the program version
--help|-h
prints this help information
--interface|-i
specifies the network interface to check


Example:

# ./check_ifconfig -i eth0
eth0 RUNNING | RX_Bytes=736019798B;;;; TX Bytes=760915818B;;;; RX_packets=3233473;;;; RX_errors=0;;;; TX_packets=2726202;;;; TX_errors=0;;;;

=============
Oct. 31, 2014 What's new in version 0.93
- the path for binary executables is no more hard coded, which makes the script capable to run on virtually any Linux or UNIX system, without the need to edit it.
- the path for binary executables (grep, sed, ifconfig) can be overwritten in the parameters section, at the beginning of the script
- introduced a new function for bringing the size strings to humanly readable format (ex.: 1024 bytes=>1KB)