RE: Please help with this strangeness

["David Gillett" <gillettdavid () fhda edu>]

  This is a kind of strange address block you've described.  Let's try
to clarify that before proceeding to the traffic itself.

  It sounds like you're trying to describe the 81.174.224.68/30 block,
that's with a subnet mask of 255.255.255.252.  Blocks this size are
sometimes used for ISP connections to sites that are NATting to internal
addresses at their border.
  Of the four addresses in the block, ONE is usable by the client.  The
'all zeros' host address 81.174.224.68 is reserved for the network; 
in most cases, it will get treated as a broadcast.  The 'all ones' address
is the normal broadcast address, and in this case it's 81.174.224.71.
  That leaves .69 and .70.  To be useful as an ISP link, one of those
is going to be assigned to a router at the ISP end of the link.  The
other one is going to be available for the client router; the ISP router's
address should be configured as the default gateway on the client router.

  So a key question is:  Does this look like what you see?  If .69 is
the address of your router, then is its default gateway address pointing
at .70?  If not, what *is* it pointing at?  Is its subnet mask
255.255.255.252?  If not, what is it?
  If these values are different from what I expect, either (a) your ISP 
connection follows some different model that would be helpful to 
understand, or (b) the traffic may be an artefact of a configuration error.

David Gillett


> -----Original Message-----
> From: Michael Thompson [mailto:mike () thompsonmike co uk]
> Sent: January 14, 2004 19:03
> To: security-basics () securityfocus com
> Subject: Please help with this strangeness
>
>
> Hi Security-basics,
>
>
> I was going through all my security logs today and I noticed something
> a little odd, and wonderd if anyone could offer any insight? I am not
> that good at detailed security!
>
> I have a IPBlock assigned from my ISP, where 81.174.224.68 to
> 81.174.224.70.
>
> As I understand it, 68 is a broadcast address, 69 is assigned to the
> router, 70 is for a server, which I dont use at the present time.
>
> Now, in my snort logs, which is connected to the outside of the
> firewall I get the following logs..
>
> [**] [1:483:2] ICMP PING CyberKit 2.2 Windows [**]
> [Classification: Misc activity] [Priority: 3] 
> 01/15-02:49:35.625784 81.174.224.69 -> 81.174.224.70
> ICMP TTL:111 TOS:0xA0 ID:45600 IpLen:20 DgmLen:92
> Type:8  Code:0  ID:512   Seq:52213  ECHO
> [Xref => http://www.whitehats.com/info/IDS154]
>
> [**] [1:483:2] ICMP PING CyberKit 2.2 Windows [**]
> [Classification: Misc activity] [Priority: 3] 
> 01/15-02:49:35.641759 81.174.224.69 -> 81.174.224.68
> ICMP TTL:110 TOS:0xA0 ID:45598 IpLen:20 DgmLen:92
> Type:8  Code:0  ID:512   Seq:51701  ECHO
> [Xref => http://www.whitehats.com/info/IDS154]
>
> [**] [1:483:2] ICMP PING CyberKit 2.2 Windows [**]
> [Classification: Misc activity] [Priority: 3] 
> 01/15-02:49:35.642071 81.174.224.69 -> 81.174.224.70
> ICMP TTL:110 TOS:0xA0 ID:45600 IpLen:20 DgmLen:92
> Type:8  Code:0  ID:512   Seq:52213  ECHO
> [Xref => http://www.whitehats.com/info/IDS154]
>
> [**] [1:483:2] ICMP PING CyberKit 2.2 Windows [**]
> [Classification: Misc activity] [Priority: 3] 
> 01/15-02:49:35.649566 81.174.224.69 -> 81.174.224.71
> ICMP TTL:111 TOS:0xA0 ID:45601 IpLen:20 DgmLen:92
> Type:8  Code:0  ID:512   Seq:52469  ECHO
> [Xref => http://www.whitehats.com/info/IDS154]
>
> [**] [1:483:2] ICMP PING CyberKit 2.2 Windows [**]
> [Classification: Misc activity] [Priority: 3] 
> 01/15-02:49:35.665945 81.174.224.69 -> 81.174.224.71
> ICMP TTL:110 TOS:0xA0 ID:45601 IpLen:20 DgmLen:92
> Type:8  Code:0  ID:512   Seq:52469  ECHO
> [Xref => http://www.whitehats.com/info/IDS154]  
>
>
> Now, I thought of welchia or one of its many variants, and all
> machines are clean, the DHCP records show only one machine on the
> network connected mostly, thats my machine. It's clean.
>
> What could be causing these broadcasts? Any one have any ideas?
>
> -- 
>
> Best regards,
>  Michael (mike () thompsonmike co uk)
>    
> Join the American Non-Sequitur Society -- we don't make 
> sense, but we do like pizza. 
>
> http://www.thompsonmike.co.uk/
> PGP KeyID := 0xA9547E32
>
> 'To see a world in a grain of sand
> And heaven in a wild flower
> To hold infinity in the palm of your hand
> And eternity in an hour'
>
> Using TheBat! Version 2.02.3 CE
> Running On Windows XP (2600, Service Pack 1)
> Sent From OneAndOne

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