tcpdump mailing list archives
Re: Data in SYN and SYN acknowledgement packets
From: "Guy Harris" <guy () alum mit edu>
Date: Tue, 5 Aug 2003 15:41:58 -0700 (PDT)
Justin Robinson said:
Can someone please confirm that these packets are not supposed to have a payload?
No, they can't confirm that, because it's not true. To quote RFC 793 "Transmission Control Protocol": Sequence Number: 32 bits The sequence number of the first data octet in this segment (except when SYN is present). If SYN is present the sequence number is the initial sequence number (ISN) and the first data octet is ISN+1. and LISTEN STATE If active and the foreign socket is specified, then change the connection from passive to active, select an ISS. Send a SYN segment, set SND.UNA to ISS, SND.NXT to ISS+1. Enter SYN-SENT state. Data associated with SEND may be sent with SYN segment or queued for transmission after entering ESTABLISHED state. so it's perfectly legitimate to put data in a SYN segment. - This is the TCPDUMP workers list. It is archived at http://www.tcpdump.org/lists/workers/index.html To unsubscribe use mailto:tcpdump-workers-request () tcpdump org?body=unsubscribe
Current thread:
- Data in SYN and SYN acknowledgement packets Justin Robinson (Aug 18)
- Re: Data in SYN and SYN acknowledgement packets Jefferson Ogata (Aug 15)
- Re: Data in SYN and SYN acknowledgement packets Justin Robinson (Aug 18)
- Re: Data in SYN and SYN acknowledgement packets Aaron Turner (Aug 15)
- Re: Data in SYN and SYN acknowledgement packets Guy Harris (Aug 15)
- Re: Data in SYN and SYN acknowledgement packets Jefferson Ogata (Aug 15)