From owner-freebsd-net Mon Oct 15 8:34:42 2001 Delivered-To: freebsd-net@freebsd.org Received: from cx175057-a.ocnsd1.sdca.home.com (cx175057-a.ocnsd1.sdca.home.com [24.4.86.45]) by hub.freebsd.org (Postfix) with ESMTP id 5ADA937B40C for ; Mon, 15 Oct 2001 08:34:27 -0700 (PDT) Received: from brian (cx175057-b.ocnsd1.sdca.home.com [24.4.87.106]) by cx175057-a.ocnsd1.sdca.home.com (8.11.6/8.11.3) with SMTP id f9FFYIY08995; Mon, 15 Oct 2001 08:34:24 -0700 (PDT) (envelope-from bri@sonicboom.org) Message-ID: <007701c1558e$585a1460$3324200a@sonicboom.org> From: "Brian" To: "Drew J. Weaver" , "'freebsd-net@freebsd.org'" References: Subject: Re: DNS causing problems with sendmail? Date: Mon, 15 Oct 2001 08:30:18 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0070_01C15553.9F600080" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4807.1700 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 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 is a multi-part message in MIME format. ------=_NextPart_000_0070_01C15553.9F600080 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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 -----=20 From: Drew J. Weaver=20 To: 'freebsd-net@freebsd.org'=20 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. =20 Does anyone have a clue on this? I'm awfully confused at this point. =20 Thanks, -Drew =20 ------=_NextPart_000_0070_01C15553.9F600080 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
After the 2 or 3 minute delay, does it = work? =20 Looked in /var/log/maillog for reject causes?  Are all the hosts = you want=20 to allow to send specified in /etc/mail/relay-domains?  If you want = to try=20 to see if dns is the cause, specify a few of the non working hosts in=20 /etc/hosts.  Personally as an isp customer, if forward and reverse = dns is=20 not setup, I'd be looking for a new isp.  Some sites will not allow = you to=20 connect in this situation.  TCP wrappers often includes this=20 entry.
 
# Prevent those with no reverse DNS = from=20 connecting.
ALL : PARANOID : RFC931 20 : deny
Bri
----- Original Message -----
From:=20 Drew J.=20 Weaver
Sent: Monday, October 15, 2001 = 5:40=20 AM
Subject: DNS causing problems = with=20 sendmail?

Hi, I've had this = problem for a=20 few days now, we have a small dial-up ISP and when users dial into one = of our=20 cities they get a 209.xxx.xxx.xxx IP and our mail server responds = normally, we=20 have another modem pool in that city that consists of 206.xxx.xxx.xxx = IP=20 addresses, if a user gets a 206.xxx.xxx.xxx IP address and they = attempt to=20 check mail it takes a good 2-3 minutes before the sendmail connection starts, which is an obvious = problem=20 because of the timeouts on email clients (and.. 2-3 minutes is just = bad). I've=20 been kinda asking around on comp.mail.sendmail about this issue and they are = telling=20 me it is a DNS problem. Well, I know that my mail server can reverse = the IP=20 addresses because if I am logged in and issue a host command with the = IP after=20 it the server is able to produce the proper reverse name. Another user = thought=20 it was because I have no Forward dns (a = record) for=20 what the IPs are reversed to, but the fact = is I've=20 NEVER had any A records or anything for my = modem=20 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.=20 So this appears to be an issue only effecting one daemon on one = server. The=20 afflicted server also runs a POP daemon that isn't having any problems = of this=20 type.

 

Does anyone have a clue = on this?=20 I'm awfully confused at this point.

 

Thanks,

-Drew

 

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