Re: DNS traffic sourced from my address space to myself.

[bmanning () vacation karoshi com]

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