[Sussex] Secure connections

Steve Dobson steve at dobson.org
Tue Jan 8 10:47:17 UTC 2008


Desmond

On Tue, 2008-01-08 at 09:39 +0000, Desmond Armstrong wrote:
> I have tried the various combinations but all refuse. By authentication 
> I assume userid and password for gmail but it fails even before asking 
> for authentication. I shall try again though.

Have you tried telnet(1)ing to the port?  Obviously for encrypted ports
all it proves is the connection, but that in itself can be useful to
know.  But for plain text ports that use ASCII commands you can check it
personally to see what's happening.  For example:

	$ telnet mail-in-01.lug.org.uk 25
T:	Trying 217.147.93.69...
T:	Connected to mail-in-01.lug.org.uk.
T:	Escape character is '^]'.
S:	220 mail-in-01.lug.org.uk ESMTP Exim 4.63 Tue, 08 Jan 2008 10:35:17
+0000
C:	EHLO example.com
S:	250-mail-in-01.lug.org.uk Hello taz.syscall.org.uk [82.68.142.129]
S:	250-SIZE 52428800
S:	250-PIPELINING
S:	250 HELP
C:	QUIT
S:	221 mail-in-01.lug.org.uk closing connection
T:	Connection closed by foreign host.
	$ 

	Where
		T	- Is output from the telnet program.
		C	- Is the client, me, what I typed.
		S	- Is output from the mail server.

The above shows me that the mail server for lug.org.uk doesn't offer any
authentication, But if I connect to a mail server that responds with a
"250-AUTH CRAM-MD5" I then know that CRAM-MD5 is available.

If you try the same trick from your home and find that instead of
blocking a port your ISP is redirecting you to one of there own servers
you might be able to determine this.  That may reveal why you have
having so little luck getting your mail to work.

Steve
-- 
Steve Dobson

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