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Got bogus unix line

UML Utilities/missing kernel hooks cause misleading error

Warning, Got Bogus UNIX Line
Re: netstat returns "warning, got bogus unix line."
Resolution: stop uml-utilities
10/05/2005

Quick update. After my next boot I found the problem is back. I stopped uml-utilities and the problem went away. I don't think I added uml hooks into the kernel the last time I compiled it. I now suspect this error is related to that condition. (I have UML on another box, with the kernel hooks in place and it does not throw the same error with netstat...)


Resolution: Re-install debian package uml-utilities
09/26/2005

This note is more a footnote than anything, and really doesn't answer the question "Why am I getting this error"

A little background. A few weeks ago I noticed a series of "warning, got bogus unix line." messages in my daily cron job's emails. Too busy, I ignored them for a while. Eventually I took the time to do a little investigating. After some checking, I discovered the line was coming from chkrootkit. This made me pay attention! ...so I dug in further. I Googled a bit, and found numerous references to virus infected systems with root kits installed. What differed with my situation is my chkrootkit wasn't saying anything about a virus, it was saying "got bogus unix line."

So I read the man page for chkrootkit in greater detail and found the "-d" parameter (debug mode). I ran it this way and found it was running netstat when it got the "bogus unix line" message. I tried running netstat by itself:

netstat -anp
and found I consistently got the "bogus" message. What was not consistent was where it appeared in the listing. This was confusing. It also made me nervous. What if my server was compromised, and the virus was smart enough to hide itself from my netstat inquiries? After a little experimenting, I found I didn't get the "bogus" message using
netstat -an --tcp
or using
netstat -an --udp
More Googling found a copy of the netstat source code and illustrated the "got bogus unix line" message only applied to unix domain sockets, not to tcp or udp. More experimenting and I finally stumbled on
netstat -anp --unix 2>&1 | grep bogus
returned consistent results, and the culprit was uml-utilities!

Armed with consistent results from netstat, I turned uml-utilities off using

/etc/init.d/uml-utilities stop
and ran the netstat command again. No Error! I turned it back on, ran the netstat command, and the error re-appeared,

So, the resolution was to re-install the package, using

apt-get install --reinstall uml-utilities
Once reinstalled, I started uml-utilities and tried netstat again. No Error!

I have neglected to mention this is a debian sarge installation using a 2.6.9 kernel.

I hope this saves at least one other person 1) the worry of thinking their server has been compromised, and 2) the time spent tracking it down! If you find this helpful, please take a moment to drop me a message using this link.

Comments

Date :  9/10/2011 9:34:04 AM
Name :  Robert
Comments :  Thanks, this saved me a lot of digging

Date :  3/19/2010 7:15:57 AM
Name :  lefty.crupps
Comments :  I was also getting that line with a run of netstat, running Debian Sid (getting to be Debian 6). The reinstall of uml-utilities and its restart has also fixed this for me.

Date :  9/10/2009 12:28:21 AM
Name :  John
Comments :  4 years later, your post just saved my day too! Exact same symptoms, exact same solution! Thanks!!

Date :  1/26/2009 12:44:01 PM
Name :  Kunthar
Comments :  Thank you very much man. You saved my day :) Peace

Date :  12/7/2008 4:13:15 AM
Name :  Richar
Comments :  Thenks!

Date :  11/13/2006 6:48:40 AM
Name :  Lee Wilding
Comments :  Very useful. Thank you

Date :  3/28/2006 3:19:03 PM
Name :  cryptomail
Comments :  1) thank goodness for google 2) thank goodness for your information

Date :  3/7/2006 2:57:30 AM
Name :  Peter
Comments :  Your information was very helpful. Got exact the same thing! Strange anyway ...

Date :  12/29/2005 12:18:03 AM
Name :  Sebastian Fischer
Comments :  I found the same error with tiger. But not with netstat and not with chkrootkit. Your Information stops the panic, the servers are cracked Thanks from Belgium. Sebastian Fischer

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