[934] in linux-net channel archive
Re: telnet/ftp/rlogin/rsh not working between Linux machines. (fwd)
daemon@ATHENA.MIT.EDU (Matthias Urlichs)
Sat Aug 19 18:20:00 1995
To: submit-linux-dev-net@ratatosk.yggdrasil.com
From: urlichs@smurf.noris.de (Matthias Urlichs)
Date: 19 Aug 1995 12:49:33 +0200
In linux.dev.net, article <199508171746.KAA18932@saguaro.flyingfox.com>,
Jim Shankland <jas@flyingfox.COM> writes:
> > > >
> > > > telnet linux3
> > > >
> > > > Connected to linux3.....
> > > > Escape characters is '^]'
> > > > Connection closed by foreign host
>
> No. The fact that the connection was accepted, then closed,
> means the telnetd service is up. It just doesn't like your
> hostname or IP address. See /etc/hosts.{allow,deny} on linux3.
>
In fact, this is highly antisocial. tcpd should at least print a one-line
"Sorry, login is disallowed from your machine". Or "Sorry, name server
entries for <your.IP> are set up incorrectly -- login disallowed".
The standard Slackware(?) setup is wrong, BTW, as tcpd also controls
SMTP connections. RFC 1123, section 5.2.5, says that you may note
mismatches in the Received: line or in your logfile but that you MUST NOT
refuse to accept a message because of mismatches. (That section appears to
cover verification of the HELO parameter only. Well, if the editor had
known of tcpd he'd have mentioned that too.)
Besides, accepting and then immediately throwing away a connection is
against quite a few RFCs. SMTP, FTP, NNTP, I can probably dig out a few
others. :-/ Unless you configure tcpd to reject callers correctly,
IMHO you shouldn't use it in the first place.
--
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