Snort mailing list archives
Re: RST vs RST|ACK
From: jbradberry () aafes com (John Benjamin Bradberry)
Date: Fri, 02 Nov 2001 10:50:14 -0600
A RST|ACK is created by a server when a connection request arrives and no server process is listening. There are only 2 times you should NOT see an ACK during 'normal' TCP: On the first segment of a connection sent by a client On RST segments used to abort a connection Now, if you see a SYN|ACK from your server on TCP 27374, that's another story! RFC 793 is a good start [see section 3.4] but I think the Stevens text is still the finest available. Also take a look at the O'Reilly book by Eric Hall. Regards. -- John Bradberry The Greentree Group Ian Melven wrote:
Hi everyone A question on portscans.. I've been scanned for SubSeven a few times.. I set up a rule to track outgoing packets from the default port (27374) with the ACK flag set.. this caught 2 machines sending RST|ACK packets in response to a SYN... Can someone explain why these are sending RST|ACK instead of just a RST ? I thought RST was the standard response to a SYN from a closed port ? Is this because the initial incoming SYN had some data in it (I believe this is allowed...) I need to get an office copy of TCP/IP Illustrated :/ thanks ! Ian
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Current thread:
- RST vs RST|ACK Ian Melven (Nov 01)
- Re: RST vs RST|ACK John Benjamin Bradberry (Nov 02)