qpopper pop3 response very slow
Our mail mail server is a 486 SuSE 6.3 system with pop3 service. We use Eudora Light version 3.06 (both 16-bit and 32-bit) clients to connect to the server. The problem we are having is that when checking for email some clients unpredictably take very long or timeout when the response takes longer than about 30 seconds. From other computers the checking of email from the same computer takes less than a second, consistently. from inetd.conf: pop3 stream tcp nowait root /usr/sbin/tcpd /usr/sbin/popper -s To test, I use telnet 192.168.1.1 110, then wait for Connected to 192.168.1.1. Escape character is '^]'. +OK QPOP (version 2.53) at gateway.iccontrols.com starting. The "Connected" and "Escape" lines come up almost immediately, but the +OK line can take > 30 seconds. To test further I also have a new machine that is 1 GHz, 1 G RAM, with SuSE 7.3 installed. I installed qpopper-4.0.3-34, then tested again with telnet. Connected to 192.168.2.1. Escape character is '^]'. +OK ready <20166.1015439267@pe01.iccontrols.com> The +OK line takes 12 seconds. Since this is a fast machine that is not doing anything else, I would expect the +OK to come up practically immediately. Any clues would be appreciated. View our website at <http://www.iccontrols.com> 1-519-941-8161, 1-800-265-9161,Fax: 1-519-941-8164, E-Mail: sales@iccontrols.com
Is it doing reverse-DNS lookups of the connecting clients? Are some of the clients included in its /etc/hosts and others aren't? Does it sometimes have trouble connecting to an external DNS server (your ISPs?) Ewan On Wed, 2002-03-06 at 19:06, Peter Bakker wrote:
Our mail mail server is a 486 SuSE 6.3 system with pop3 service. We use Eudora Light version 3.06 (both 16-bit and 32-bit) clients to connect to the server.
The problem we are having is that when checking for email some clients unpredictably take very long or timeout when the response takes longer than about 30 seconds. From other computers the checking of email from the same computer takes less than a second, consistently.
from inetd.conf: pop3 stream tcp nowait root /usr/sbin/tcpd /usr/sbin/popper -s
To test, I use telnet 192.168.1.1 110, then wait for
Connected to 192.168.1.1. Escape character is '^]'. +OK QPOP (version 2.53) at gateway.iccontrols.com starting.
The "Connected" and "Escape" lines come up almost immediately, but the +OK line can take > 30 seconds.
To test further I also have a new machine that is 1 GHz, 1 G RAM, with SuSE 7.3 installed. I installed qpopper-4.0.3-34, then tested again with telnet.
Connected to 192.168.2.1. Escape character is '^]'. +OK ready <20166.1015439267@pe01.iccontrols.com>
The +OK line takes 12 seconds. Since this is a fast machine that is not doing anything else, I would expect the +OK to come up practically immediately.
Any clues would be appreciated.
View our website at <http://www.iccontrols.com> 1-519-941-8161, 1-800-265-9161,Fax: 1-519-941-8164, E-Mail: sales@iccontrols.com
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Is it doing reverse-DNS lookups of the connecting clients?
I don't know. Internally most of the host addresses are hard-coded with IP addresses. For example, the Eudora clients all directly access the pop3 server as 192.168.1.1. DNS-lookup timeouts does make some sense. Is there a way to get the pop3 server to not do DNS lookups for connecting clients?
Are some of the clients included in its /etc/hosts and others aren't?
That is true. Just checking /etc/hosts, the workstations which have entries in /etc/hosts connect quickly, the others sometimes have problems. Maybe this is more than a coincidence. I will do a test--add the troublesome workstation to /etc/hosts in the pop3 server and see if that fixes the problem for that particular situation.
Does it sometimes have trouble connecting to an external DNS server (your ISPs?)
Not that I am aware of. The workstations are currently configured to use the DNS of our ISP, and web browsing and DNS works fine.
Ewan
On Wed, 2002-03-06 at 19:06, Peter Bakker wrote:
Our mail mail server is a 486 SuSE 6.3 system with pop3 service. We use Eudora Light version 3.06 (both 16-bit and 32-bit) clients to connect to the server.
The problem we are having is that when checking for email some clients unpredictably take very long or timeout when the response takes longer than about 30 seconds. From other computers the checking of email from the same computer takes less than a second, consistently.
from inetd.conf: pop3 stream tcp nowait root /usr/sbin/tcpd /usr/sbin/popper -s
To test, I use telnet 192.168.1.1 110, then wait for
Connected to 192.168.1.1. Escape character is '^]'. +OK QPOP (version 2.53) at gateway.iccontrols.com starting.
The "Connected" and "Escape" lines come up almost immediately, but the +OK line can take > 30 seconds.
To test further I also have a new machine that is 1 GHz, 1 G RAM, with SuSE 7.3 installed. I installed qpopper-4.0.3-34, then tested again with telnet.
Connected to 192.168.2.1. Escape character is '^]'. +OK ready <20166.1015439267@pe01.iccontrols.com>
The +OK line takes 12 seconds. Since this is a fast machine that is not doing anything else, I would expect the +OK to come up practically immediately.
Any clues would be appreciated.
Just to follow up with a thank-you note, cluing in on the reverse-DNS timeout was the key to the problem. I added entries in /etc/hosts for each of the hosts that use pop3, and now checking for email has improved from unreliable or impossible to zippy (e.g. less than 1 sec) even with the server being a 486. My users and myself are happy again and my phone has stopped ringing. At 08:04 PM 3/6/02 +0000, you wrote:
Is it doing reverse-DNS lookups of the connecting clients?
Are some of the clients included in its /etc/hosts and others aren't? Does it sometimes have trouble connecting to an external DNS server (your ISPs?)
Ewan
On Wed, 2002-03-06 at 19:06, Peter Bakker wrote:
Our mail mail server is a 486 SuSE 6.3 system with pop3 service. We use Eudora Light version 3.06 (both 16-bit and 32-bit) clients to connect to the server.
The problem we are having is that when checking for email some clients unpredictably take very long or timeout when the response takes longer than about 30 seconds. From other computers the checking of email from the same computer takes less than a second, consistently.
from inetd.conf: pop3 stream tcp nowait root /usr/sbin/tcpd /usr/sbin/popper -s
To test, I use telnet 192.168.1.1 110, then wait for
Connected to 192.168.1.1. Escape character is '^]'. +OK QPOP (version 2.53) at gateway.iccontrols.com starting.
The "Connected" and "Escape" lines come up almost immediately, but the +OK line can take > 30 seconds.
To test further I also have a new machine that is 1 GHz, 1 G RAM, with SuSE 7.3 installed. I installed qpopper-4.0.3-34, then tested again with telnet.
Connected to 192.168.2.1. Escape character is '^]'. +OK ready <20166.1015439267@pe01.iccontrols.com>
The +OK line takes 12 seconds. Since this is a fast machine that is not doing anything else, I would expect the +OK to come up practically immediately.
Any clues would be appreciated.
View our website at <http://www.iccontrols.com> 1-519-941-8161, 1-800-265-9161,Fax: 1-519-941-8164, E-Mail: sales@iccontrols.com
participants (2)
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Ewan Leith -
Peter Bakker