nanog mailing list archives
Re: Barracuda Networks Spam Firewall
From: jlewis () lewis org
Date: Mon, 17 May 2004 17:39:37 -0400 (EDT)
On Mon, 17 May 2004, Jared B. Reimer wrote:
We had this problem when our inbound-smtp server ( the server the barracuda is dumping mail to) was accepting all RCPT TOs: As a result dictionary attacks were getting through and creating 'unique recipients' on the Barracuda. As soon as I fixed my mail server to reject with a 220 error on bogus RCPT TOs the problem cleared up.This is a pretty serious flaw IMHO, if it is (in fact) true. qmail isn't the only mailer that behaves this way. It looks like they may have tried to kludge their way around this with LDAP in the case of MS Exchange, which also does asynchronous bouncing of undeliverable mail IIRC.
The fault here is with qmail. The barracuda was doing exactly what it was designed to do. qmail can be patched to be smarter (google for qmail spamcontrol or magic smtpd). Accept all, then try to bounce, is a recipe for disaster with today's dictionary attackers and virii that will send to randomly created destinations from randomly created forged froms. ---------------------------------------------------------------------- Jon Lewis *jlewis () lewis org*| I route Senior Network Engineer | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
Current thread:
- Re: Barracuda Networks Spam Firewall, (continued)
- Re: Barracuda Networks Spam Firewall Matthew Crocker (May 18)
- Re: Barracuda Networks Spam Firewall Martin Hepworth (May 18)
- Port 5000 Geo. (May 18)
- Re: Port 5000 Erik Haagsman (May 18)
- Re: Port 5000 Doug White (May 18)
- Re: Port 5000 James Reid (May 18)
- Re: Barracuda Networks Spam Firewall Jared B. Reimer (May 17)
- Re: Barracuda Networks Spam Firewall Jared B. Reimer (May 17)
- Re: Barracuda Networks Spam Firewall jlewis (May 17)
- Re: Barracuda Networks Spam Firewall Majdi S. Abbas (May 18)
- Re: Barracuda Networks Spam Firewall Valdis . Kletnieks (May 18)
- Re: Barracuda Networks Spam Firewall Christopher X. Candreva (May 18)
- Re: Barracuda Networks Spam Firewall Valdis . Kletnieks (May 18)
- Re: Barracuda Networks Spam Firewall Todd Vierling (May 18)
- Re: Barracuda Networks Spam Firewall Christopher X. Candreva (May 18)
- Re: Barracuda Networks Spam Firewall Valdis . Kletnieks (May 18)