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Re: [LUG] rootkit, chkrootkit

 

On Fri, Oct 07, 2005 at 09:30:15PM +0100, Grant Sewell wrote:
> On Thu, 6 Oct 2005 21:10:08 +0100
> Henry Bremridge wrote:
> 
> > I installed chkrootkit (debian sarge) and the first night I received the
> > following email:
> > 
> > ----- Forwarded message from Cron Daemon <root@newdebian> -----
> > 
> > Subject: Cron <root@newdebian> test -x /usr/sbin/anacron || run-parts --report 
> > /etc/cron.daily
> > Date: Tue, 04 Oct 2005 06:25:30 +0100
> > 
> > /etc/cron.daily/chkrootkit:
> > eth0: PACKET SNIFFER(/sbin/dhclient[2834])
> > 
> > ----- End forwarded message -----
> > 
> > 
> > I have just checked this out on google and the only message I got was
> > versions of the following: "dhclient does set some socket options which
> > chkrootkit might detect as sniffing. Basically, dhclient needs to accept
> > any traffic, because it runs before the interface has an IP. That's my
> > guess, at least, sorry for the non-confidence inspiring lack of
> > technical details."
> > 
> > Can anyone comment?
> > 
> > Many thanks
> 
> Don't know much about root-kits or chkrootkit either for that matter, but the 
> above sounds semi plausible.  A dhcp client does need to accept traffic from 
> anywhere due to the broadcast nature of the dhcp offer/acknowledge/accept process, 
> but IIRC all dhcp communications occur on specific port numbers for both the 
> sending and receiving on both server and client (unlike ordinary traffic which 
> only uses specific port numbers for the server side), so I am not certain as to 
> the above statement's technical validity.
> 
> Or I could be wrong.
> 
> Grant.

Still not sure about the dhclient but have checked the system
with http://www.inside-security.de/insert_en.html and all was negitive

> 

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