I'm having trouble getting SMTP AUTH to work on our network, even across network segments that have no specific access-list rules between them. Perhaps there's something in the CBAC setting that prevents AUTH from working properly?
Our mail server software with relay enabled for everybody...external clients sent message, and it goes through fine.
external clients sent message, server replies with "relay not permitted" (expected, good)
Enabled AUTH on server and set clients to authenticate...
external cleints sent message, get back error message...
"Your server has unexpectedly terminated the connection. Possible causes for
this include server problems, network problems, or a long period of
The Cisco IOS firewall has a built-in feature that assures that snmp conforms to the recommendations listed in RFC 821, section 4.5.1. This section lists the commands that should be allowed through a firewall (HELO, MAIL, RCTP, DATA, RSET, NOOP and QUIT). The cisco IOS firewall is configured to allow only the above commands and disallow any other command. You can disable this feature by typing 'no ip inspect -name- smtp'. SNMP will still be allowed (if permitted by rules), but the IOS FW will not check for imbedded commands in SMTP.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...