DNS traffic sourced from my address space to myself.

Wed Jul 7 16:26:41 UTC 2010

On Wed, Jul 07, 2010 at 08:07:07AM -0400, Drew Weaver wrote:
> Howdy,
> 
> Recently I have been noticing a good amount of totally bogus DNS traffic coming in on my transit links via my own IP addresses (spoofed). 
> 
> SLOT 2:Jul  2 11:26:02 EDT: %SEC-6-IPACCESSLOGP: list 119 permitted udp x.x.145.161(0) -> x.x.145.235(0), 1 packet
> SLOT 2:Jul  2 11:26:02 EDT: %SEC-6-IPACCESSLOGP: list 119 permitted udp x.x.146.74(0) -> x.x.145.235(0), 1 packet
> SLOT 2:Jul  2 11:26:02 EDT: %SEC-6-IPACCESSLOGP: list 119 permitted udp x.x.146.70(0) -> x.x.145.235(0), 1 packet
> SLOT 2:Jul  2 11:26:02 EDT: %SEC-6-IPACCESSLOGP: list 119 permitted udp x.x.146.57(0) -> x.x.145.235(0), 1 packet
> 
> There are multiple different instances of this traffic, the pattern seems to be:
> 
> -The source is always 'my own IPs' and obviously spoofed.
> -It's DNS traffic
> -The "source addresses" all seem to be randomly chosen from the same /23 as the destination address (they cycle through randomly).
> 
> Has anyone else noticed anything similar coming in on their transit links or am I just lucky?
> 
> Normally my iACL catches this but I've just been noticing more of it lately.
> 
> -Drew
> 
> 

	Yeah... I've seen this type of behaviour w/ folks picking random source addresses
	from the IPv6 /32...  Sure wish I could announce something smaller.

--bill