Network grep

Thresher

Article from Issue 148/2013
Author(s):

Ngrep is a pattern-matching tool that sorts the wheat from the chaff and doubles as a lightweight packet sniffer.

You might want to inspect your network at a very detailed level for a number of legitimate reasons. Much of the time, it’s to debug an application that’s misbehaving and connecting to a server on the wrong port, or maybe a colleague has noticed a slowdown on a particular network link, and you need to diagnose where the sudden flood of multidirectional traffic is coming from.

On the other hand, you might need to check the exact nature of an attack and perform some realtime forensic diagnostics to circumvent it. Leaving the networking aspects aside for a moment, even an admin solely responsible for systems and not networks (an exceptionally rare remit these days, admittedly) needs a highly functional packet sniffer available at all times. Because systems rely so heavily on connectivity for multifaceted Internet usage, it’s imperative for admins to be able to inspect the contents of the network deeply and interpret the results proficiently.

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