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Re: [afnog] [Fwd: mail.one2net.co.ug security run output]




----- Original Message -----
From: Patrick Okui <pokui at one2net.co.ug>
Date: 19 Aug 2003 09:44:42 +0300
To: afnog at afnog.org
Subject: [afnog] [Fwd: mail.one2net.co.ug security run output]

> Got this in my logs... I can't seem to trace the renegade MAC address.
> Any reason this would happen the 216.250.215.15 should be a broadcast
> for one of my small services shouldn't it? Any clues on how to debug
> this?
> 
> 
> -----Forwarded Message-----
> 
> From: Charlie Root <root at mail.one2net.co.ug>
> To: root at mail.one2net.co.ug
> Subject: mail.one2net.co.ug security run output
> Date: 19 Aug 2003 03:01:03 +0300
> <snip>
> 
> mail.one2net.co.ug kernel log messages:
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> > arp: 00:50:ba:8c:57:e1 attempts to modify permanent entry for 216.250.215.15 on rl0
> 
> mail.one2net.co.ug login failures:
> 
> mail.one2net.co.ug refused connections:
> 
> -- End of security output --
>  
> the commands below give...
> 
> mail# arp -a
> 
> ? (216.250.215.9) at 00:d0:ba:58:ee:e0 on rl0 [ethernet]
> ns.one2net.co.ug (216.250.215.10) at 00:50:ba:85:ca:82 on rl0 [ethernet]
> ? (216.250.215.15) at ff:ff:ff:ff:ff:ff on rl0 permanent [ethernet]
> 
> mail# netstat -rn
> 
> Routing tables
>                                                                                                             
> Internet:
> Destination        Gateway            Flags    Refs      Use  Netif Expire
> default            216.250.215.9      UGSc       15     3424    rl0
> 127.0.0.1          127.0.0.1          UH          0    45082    lo0
> 216.250.215.8/29   link#1             UC          3        0    rl0
> 216.250.215.9      00:d0:ba:58:ee:e0  UHLW       16        0    rl0    617
> 216.250.215.10     00:50:ba:85:ca:82  UHLW        0      228    rl0   1191
> 216.250.215.15     ff:ff:ff:ff:ff:ff  UHLWb       0       22    rl0
>                           
> 
> __________________________________________________
> This is the Africa Network Operators' Group(AfNOG) 
> technical discussion list.
> The AfNOG website is: <http://www.afnog.org>



this is an attempt to poison the arp-cache for that particular host. 
or it is possible that another machine on your network has the same address or some linux box is announcing arp for all interfaces. try using tcpdump.
see http://www.bth.se/ces/ces.nsf/0/cd4076ac21f045b8c1256a690047dbb9/$FILE/Lindman.pdf  
g00gler

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This is the Africa Network Operators' Group(AfNOG) 
technical discussion list.
The AfNOG website is: <http://www.afnog.org>