[Dshield] smtp test for open relay

Tom Laermans tom.laermans at powersource.cx
Mon Jun 23 14:23:10 GMT 2003


At 16:11 23-06-2003, you wrote:
>Uhm . . . No, sorry.  His advice was sound.  Another way is to use
>Netcat, but telnet <host> 25 works just fine if you want to connect to
>smtp.

Uhm.. did you actually try telnetting to 23 to see what it did?
His advice was the same that was given a few times before, but that doesn't 
really help.
Simple relaying can be tested with that, if you know the SMTP protocol, but 
if you check the tests ordb, mail-abuse, et al do, you'll see there's way 
more ways to relay through a seemingly-closed server sometimes.

telnet relay-test.mail-abuse.org

is the way to go. port 23.

Tom


> > -----Original Message-----
> > From: Fred Grayson [mailto:fred at fred-grayson.net]
> > Sent: Monday, June 23, 2003 7:02 AM
> > To: list at dshield.org
> > Subject: [Dshield] smtp test for open relay
> >
> >
> > Incorrect advice Joe. Connecting to the telnet port is the
> > way it works.
> >
> > >Try telnet relay-test.mail-abuse.org 25
> > >
> > >Without the 25 you'll be attempting a telnet session and
> > >not a SMTP session.
> > >After connecting, you'll need to spoof an SMTP transaction using the
> > >traditional helo, mail from: , and rcpt to: followed by data
> > then the
> > >content.
> > >
> > >cheers
> > >-Joe
> > >
> > >-----Original Message-----
> > >From: Fred Grayson [mailto:fred at fred-grayson.net]
> > >Sent: Monday, June 23, 2003 9:12 AM
> > >To: list at dshield.org
> > >Subject: [Dshield] smtp test for open relay
> > >
> > >
> > >>Hi.
> > >>
> > >>Do you have links to ips web sites (or others) that test for open
> > >>relays for an IP ?  I've got one to test and I don't know
> > where to go.
> > >
> > >If you have access to the machine running the mail server
> > itself, you
> > >can test it. Just run this from a shell:
> > >
> > >telnet relay-test.mail-abuse.org
> > >
> > >
> > >
> >
> >
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> >
>
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