I see that port 113 was one of those originally set up for Exchange on my firewall -- Exch2K/W2K doesn't require it? I'm happy to reject it if not needed.
-----Original Message----- From: Andy David [mailto:[EMAIL PROTECTED]] Sent: Friday, May 10, 2002 6:30 AM To: Exchange Discussions Subject: RE: smtp - UDP, TCP, or IP? Dont need to. However , you should reject 113 - dont merely drop it. -----Original Message----- From: Hansen, Eric [mailto:[EMAIL PROTECTED]] Sent: Friday, May 10, 2002 9:07 AM To: Exchange Discussions Subject: RE: smtp - UDP, TCP, or IP? Wow I have a lot to learn then, I don't even know what a 'tcp sny' packet is. If I have port 25 open wouldn't that imply that I'm not blocking tcp syn packets on port 25? Would that be the difference between using the ip permit over the tcp permit statements? Also, should I have port 113 open? It sounds like I should. Much thanks. e- -----Original Message----- From: Benjamin Scott [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 09, 2002 4:58 PM To: Exchange Discussions Subject: Re: smtp - UDP, TCP, or IP? On Thu, 9 May 2002, at 6:35pm, Hansen, Eric wrote: > As part of our access statement we used "tcp permit" for 110 and 25. > Well it turned out that by doing this mail came in but didn't go out. SMTP is TCP port 25. SMTP does not use UDP, not is it an IP-layer protocol. Make sure you have all the rules, and in all directions. Maybe you are accidentally blocking outbound TCP SYN packets on port 25? Also, if your default policy is to drop without reply, make sure you at least send a TCP RST for connect attempts to TCP port 113, which is the "auth" protocol (also called "ident"). Many SMTP mail exchangers will do an "auth" query, and if you just drop those packets on the floor, they may time out or reject you. If all else fails, use a packet sniffer to see what is going over the wire. -- Ben Scott <[EMAIL PROTECTED]> | The opinions expressed in this message are those of the author and do | not | | necessarily represent the views or policy of any other person, entity | or | | organization. All information is provided without warranty of any | kind. | _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] ------------------------------------------------------------------------------ The information contained in this email message is privileged and confidential information intended only for the use of the individual or entity to whom it is addressed. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copy of this message is strictly prohibited. If you have received this email in error, please immediately notify Veronis Suhler Stevenson by telephone (212)935-4990, fax (212)381-8168, or email ([EMAIL PROTECTED]) and delete the message. Thank you. ============================================================================== _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED]
