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From: tong@aussie.enet.dec.com (Benny Tong)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: tcp source port number assignment in new tcp connection
Keywords: Telnet, source port number
Message-ID: <1990Sep7.095512@aussie.enet.dec.com>
Date: 7 Sep 90 00:03:18 GMT
References: <9009061442.AA28405@ftp.com>
Sender: newsdaemon@shlump.nac.dec.com
Reply-To: tong@aussie.enet.dec.com (Benny Tong)
Organization: Digital Equipment Corporation
Lines: 16

In article <9009061442.AA28405@ftp.com>, jbvb@FTP.COM (James B. Van Bokkelen)
writes:
>If you start at 1024, you won't fall afoul of the machines that
|>believe that reserved ports end there, instead of at 1000.  Some
|>systems expect all connections for particular protocols to use source
|>ports between 600 and 1024, but other protocols are required to
|>originate from ports numbered above 1024.  If you're actively opening
|>an FTP data connection from a server, you'll find that there are
|>machines that insist the originating port be 20.  Otherwise, fine.

Does anyone know which protocol on which system requires source ports to
between 600 and 1024, and which protocol requires source port to be above
1024.

I assume it is safe for Telnet to connect to all systems with a source port 
number above 1024. Isn't it?