-----Original Message-----
From: Craig Bowers [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, January 08, 2003 9:30 AM
To: SIMS Discussions
Subject: Re: Open relay detected within your network



> ... one can only wonder. What the router line says is, "if I receive
mail for 3-rivers.com, relay it to 3-rivers.com's smtp server"

Quibbling with your wording, but the secondary is a 3-rivers.com smtp
server as well.  I'd word it more like :if I receive mail for
3-rivers.com, do a DNS lookup on 3-rivers.com and pass it to the first
MX available with a higher priority (lower MX value) than me (a backup
MX server), starting with the highest priority (lowest MX value).

So it may well deliver to the primary 3-rivers.com smtp server, but it
may instead deliver to any other smtp server (on or off 3-rivers.com
network) depending on what the 3-rivers.com DNS lists as MX records.

So for example if I was a blackhat hacker and I wanted to make life
difficult for 3-rivers.com and I could gain DNS control at 3-rivers.com,
I could add an MX record for the ordb.org smtp server to the
3-rivers.com domain.  3-rivers.com's secondary server would then happily
relay/forward mail to ordb.org, and 3-rivers.com would get RBL
blacklisted without even touching the SIMS boxes.

Follow-up question:

Do you have the IP of the primary SMTP server in the client list of your
secondary?

I'm puzzled what generates the "will relay for a client" on your
secondary.

In my own system which passes the ordb tests, I have the IP of the
secondary in the primaries client list, but the client list on my
secondary is empty.

I wouldn't have a need even for the secondary IP to be listed as a
client on the primary (the .smtp rounter entry alone is sufficient),
except that I've had some instances where spammers have gotten my
primary to temp ban my secondary.

Oh, and I'm using 1.8b9d14


#############################################################
This message is sent to you because you are subscribed to
  the mailing list <[EMAIL PROTECTED]>.
To unsubscribe, E-mail to: <[EMAIL PROTECTED]>
To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]>
To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]>
Send administrative queries to  <[EMAIL PROTECTED]>

Reply via email to