Re: Interesting traffic...

[Ashley Thomas <athomas () unity ncsu edu>]

some observations:

127.0.0.1 should never be seen as src/dst ip on the network.
and moreover if the dst ip is 127.0.0.1 as dest ip it cannot come from
outside for obvious reasons.

so i think the direction is correctly shown by Snort.
and it can be from outside.

TTL: 63 --> it must have been 64 and reduced once by your Firewall.

what can be the reason for MSS 16344 in 1st packet and 1460 in 2nd ?
is it trying some kind of negotiation ..reducing it after the first try.

Window size is also 0xFFFF !!

-ashley


On Tue, 26 Feb 2002, Mark Mason wrote:

> Finally some interesting traffic. I know the IP is spoofed, but is there any
> way snort might have gotten the direction of the traffic confused ? As it is
> it appears to come from inside my network (it could happen) the obscured
> address is a real IP, but doesn't appear to be up now. It is interesting
> that the MSS is very high on the first packet. Any idea what this could be
> caused by ?
>
> [**] [1:528:2] BAD TRAFFIC loopback traffic [**]
> [Classification: Potentially Bad Traffic] [Priority: 2]
> 02/26-11:25:30.667238 127.0.0.1:15158 -> xxx.xxx.xxx.xxx:6473
> TCP TTL:63 TOS:0x0 ID:9155 IpLen:28 DgmLen:68 DF
> IP Options (2) => LSRR NOP
> ******S* Seq: 0x1BE3F7DA  Ack: 0x0  Win: 0xFFFF  TcpLen: 40
> TCP Options (6) => MSS: 16344 NOP WS: 1 NOP NOP TS: 281854 0
>
> [**] [1:528:2] BAD TRAFFIC loopback traffic [**]
> [Classification: Potentially Bad Traffic] [Priority: 2]
> 02/26-11:25:33.657238 127.0.0.1:15158 -> xxx.xxx.xxx.xxx:6473
> TCP TTL:63 TOS:0x0 ID:9156 IpLen:28 DgmLen:68 DF
> IP Options (2) => LSRR NOP
> ******S* Seq: 0x1BE3F7DA  Ack: 0x0  Win: 0xFFFF  TcpLen: 40
> TCP Options (6) => MSS: 1460 NOP WS: 1 NOP NOP TS: 282154 0
>
> [**] [1:528:2] BAD TRAFFIC loopback traffic [**]
> [Classification: Potentially Bad Traffic] [Priority: 2]
> 02/26-11:25:36.657238 127.0.0.1:15158 -> xxx.xxx.xxx.xxx:6473
> TCP TTL:63 TOS:0x0 ID:9157 IpLen:28 DgmLen:68 DF
> IP Options (2) => LSRR NOP
> ******S* Seq: 0x1BE3F7DA  Ack: 0x0  Win: 0xFFFF  TcpLen: 40
> TCP Options (6) => MSS: 1460 NOP WS: 1 NOP NOP TS: 282454 0
>
>
>
>
>
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