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From: jbvb@FTP.COM (James B. Van Bokkelen)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: MacTCP has bad segment size
Message-ID: <9103291708.AA29336@ftp.com>
Date: 29 Mar 91 17:08:31 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: jbvb@ftp.com
Organization: The Internet
Lines: 17


    Ethernet:  ( router -> pop host)  type: IP(0x0800)
    Internet:    Mac IP -> pop host IP  hl: 6  ver: 4  tos: 0
     len: 48  id: 0x0009  fragoff: 0  flags: 00  ttl: 58  prot: TCP(6)
     xsum: 0x6a75 bsec resv 4:
    TCP:  10593 -> POP-2(109)  seq: 5d60a560  ack: ----
     win: 11648  hl: 6  xsum: 0x3a3a  urg: 0  flags: <SYN>  mss: 576

    ...  The thing I have never seen in a TCP packet before is the
    "bsec resv 4:".

LANWatch is telling you that your IP header contains the "Basic Security"
IP option, with a "reserved" classification value.  This might well be
the problem - many hosts can't grok IP packets with options.

James B. VanBokkelen		26 Princess St., Wakefield, MA  01880
FTP Software Inc.		voice: (617) 246-0900  fax: (617) 246-0901