From owner-freebsd-net Mon Oct 15 8:49:58 2001 Delivered-To: freebsd-net@freebsd.org Received: from mailman.thenap.com (mailman.thenap.com [209.190.0.10]) by hub.freebsd.org (Postfix) with ESMTP id 4A20E37B410 for ; Mon, 15 Oct 2001 08:49:40 -0700 (PDT) Received: by MAILMAN with Internet Mail Service (5.5.2653.19) id <42VNJD79>; Mon, 15 Oct 2001 11:53:54 -0400 Message-ID: From: "Drew J. Weaver" To: 'Brian' Cc: "'freebsd-net@freebsd.org'" Subject: RE: DNS causing problems with sendmail? Date: Mon, 15 Oct 2001 11:53:48 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C15591.9414BB10" Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C15591.9414BB10 Content-Type: text/plain After 2 or 3 minutes it does work, the weird thing is that it was working No problem for 2 years and then suddenly it stopped working. Yes, our modem pool IP addresses all have PTR records, just not forward DNS (we aren't that stupid). When I specify a few of the non working hosts in /etc/hosts it works fine then. One of the IP addresses in question is 206.222.10.7, if you do a host 206.222.10.7 it does reverse. So I guess my question is, what the dilly-o? -----Original Message----- From: Brian [mailto:bri@sonicboom.org] Sent: Monday, October 15, 2001 11:30 AM To: Drew J. Weaver; 'freebsd-net@freebsd.org' Subject: Re: DNS causing problems with sendmail? After the 2 or 3 minute delay, does it work? Looked in /var/log/maillog for reject causes? Are all the hosts you want to allow to send specified in /etc/mail/relay-domains? If you want to try to see if dns is the cause, specify a few of the non working hosts in /etc/hosts. Personally as an isp customer, if forward and reverse dns is not setup, I'd be looking for a new isp. Some sites will not allow you to connect in this situation. TCP wrappers often includes this entry. # Prevent those with no reverse DNS from connecting. ALL : PARANOID : RFC931 20 : deny Bri ----- Original Message ----- From: Drew J. Weaver To: 'freebsd-net@freebsd.org' Sent: Monday, October 15, 2001 5:40 AM Subject: DNS causing problems with sendmail? Hi, I've had this problem for a few days now, we have a small dial-up ISP and when users dial into one of our cities they get a 209.xxx.xxx.xxx IP and our mail server responds normally, we have another modem pool in that city that consists of 206.xxx.xxx.xxx IP addresses, if a user gets a 206.xxx.xxx.xxx IP address and they attempt to check mail it takes a good 2-3 minutes before the sendmail connection starts, which is an obvious problem because of the timeouts on email clients (and.. 2-3 minutes is just bad). I've been kinda asking around on comp.mail.sendmail about this issue and they are telling me it is a DNS problem. Well, I know that my mail server can reverse the IP addresses because if I am logged in and issue a host command with the IP after it the server is able to produce the proper reverse name. Another user thought it was because I have no Forward dns (a record) for what the IPs are reversed to, but the fact is I've NEVER had any A records or anything for my modem pools. I also have another server running the same version of sendmail, and if I dial into this city and get a 206.xxx.xxx.xxx IP and telnet to port 25 on that server it comes up instantly. So this appears to be an issue only effecting one daemon on one server. The afflicted server also runs a POP daemon that isn't having any problems of this type. Does anyone have a clue on this? I'm awfully confused at this point. Thanks, -Drew ------_=_NextPart_001_01C15591.9414BB10 Content-Type: text/html Content-Transfer-Encoding: quoted-printable

After 2 or 3 minutes it does work, = the weird thing is that it was working No problem for 2 years and then = suddenly it stopped working. Yes, our modem pool IP addresses all have PTR records, = just not forward DNS (we aren't that stupid). When I specify a few of the = non working hosts in /etc/hosts it works fine then. One of the IP addresses in = question is 206.222.10.7, if you do a host 206.222.10.7 it does reverse. So I guess = my question is, what the dilly-o?

 

=

-----Original = Message-----
From: Brian [mailto:bri@sonicboom.org]
Sent: = Monday, October 15, = 2001 11:30 AM
To: Drew J. Weaver; 'freebsd-net@freebsd.org'
Subject: Re: DNS causing = problems with sendmail?

 

After the 2 or 3 minute = delay, does it work?  Looked in /var/log/maillog for reject causes?  Are = all the hosts you want to allow to send specified in = /etc/mail/relay-domains?  If you want to try to see if dns is the cause, specify a few of the non = working hosts in /etc/hosts.  Personally as an isp customer, if forward and = reverse dns is not setup, I'd be looking for a new isp.  Some sites will not = allow you to connect in this situation.  TCP wrappers often includes this = entry.

 

# Prevent those with no = reverse DNS from connecting.
ALL : PARANOID : RFC931 20 : deny

Bri

----- Original Message = -----

Sent: Monday, October 15, = 2001 5:40 AM

Subject: DNS causing problems with sendmail?

 

Hi, = I've had this problem for a few days now, we have a small dial-up ISP and when users = dial into one of our cities they get a 209.xxx.xxx.xxx IP and our mail = server responds normally, we have another modem pool in that city that = consists of 206.xxx.xxx.xxx IP addresses, if a user gets a 206.xxx.xxx.xxx IP = address and they attempt to check mail it takes a good 2-3 minutes before the = sendmail connection starts, which is an obvious problem because of the timeouts = on email clients (and.. 2-3 minutes is just bad). I've been kinda asking around = on comp.mail.sendmail about this issue and they are telling me it is a DNS problem. Well, I know that my mail server can reverse the IP addresses = because if I am logged in and issue a host command with the IP after it the = server is able to produce the proper reverse name. Another user thought it was = because I have no Forward dns (a record) for what the IPs are reversed to, but = the fact is I've NEVER had any A records or anything for my modem pools. I also = have another server running the same version of sendmail, and if I dial into = this city and get a 206.xxx.xxx.xxx IP and telnet to port 25 on that server = it comes up instantly. So this appears to be an issue only effecting one daemon = on one server. The afflicted server also runs a POP daemon that isn't having = any problems of this type.

 

Does = anyone have a clue on this? I'm awfully confused at this = point.

 

Thanks,

-Drew

 

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