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From: clynn@BBN.COM (Charles Lynn)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Warning: Keep-Alive considered harmful
Message-ID: <9011202147.AA26071@ucbvax.Berkeley.EDU>
Date: 20 Nov 90 13:28:30 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 2

The old TOPS-20 TCP/IP used the RST method of probing for half-open
connections, by sending an unacceptable "SYN-ACK".