Please Help! How to STOP them...

Bill Moran wmoran at
Fri Jan 12 21:48:05 UTC 2007

In response to VeeJay <maanjee at>:

> I am reading many hundred lines similar to below mentioned?
> Could you please advise me what to do and how can I make my box more secure?
> Jan  9 17:54:42 localhost sshd[5130]: reverse mapping checking getaddrinfo
> for [] failed - POSSIBLE
> Jan  9 17:54:42 localhost sshd[5130]: Invalid user sysadmin from

Somebody is trying to break in to your system:

In order to stop the messages, disconnect the system from the Internet,
the attacker will then be unable to reach it.

There are, however, less drastic workarounds.  An exercise with google will
turn up a number of programs that will reduce the problem to a manageable
level.  This topic comes up about once a week on this list alone.

Bill Moran
Collaborative Fusion Inc.

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