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Old 08-25-2008, 05:03 PM   #1
davidstvz
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major log in initializing or (reawakening) network connections


That should read major *lag* ... not log

I'm running Suse Linux 10. Whether I connect via SSH, leave an open SSH window for 30 seconds and then try to begin using it again or try to access a user webpage, the server is really slow to respond. Once the response has been made, it's quick unless you leave the connection alone for 20 to 30 seconds (or more of course) then it will have to redo whatever it is it does when you start a connection.

The server is running on good hardware and I've seen much more ancient machines be far more responsive. Anyone know any configuration changes I can make to different network devices that might speed things up for me?
 
Old 08-25-2008, 09:20 PM   #2
Mr. C.
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This is typical of a DNS problem. Check your DNS to ensure that the server can quickly and reliably resolve the client's A and PTR records.
 
Old 08-25-2008, 10:12 PM   #3
davidstvz
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"This is typical of a DNS problem. Check your DNS to ensure that the server can quickly and reliably resolve the client's A and PTR records."

I'll try that if I can figure out what all that means.

EDIT:

Ok, I understand what that means now, but I don't understand what I can do about it. My network settings look good and are configured no differently than I've ever configured them (all I ever touch is the IP, Subnet mask, gateway and two dns servers).

Last edited by davidstvz; 08-25-2008 at 10:21 PM.
 
Old 08-25-2008, 10:19 PM   #4
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Correct re: primary DNS. You want the most reliable, fastest DNS server listed as the first nameserver. Any non-responsive DNS server will cause delays. Remove any non-responsive nameserver lines from your /etc/resolv.conf.

From the SSH server, you can query DNS entries:

dig A ssh_clients_hostname
dig -x ssh_clients_ip

Look at the ANSWER sections, and the Query time listed at the bottom of the results.

Last edited by Mr. C.; 08-25-2008 at 10:21 PM.
 
Old 08-25-2008, 10:30 PM   #5
davidstvz
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the primary seems to be quite responsive (0 msec many times, 40ish a few times, a whole 170 once)... the lag I'm experiencing is on the order of several seconds (as many as 9 or 10 sometimes).
 
Old 08-25-2008, 10:41 PM   #6
Mr. C.
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The DNS resolver must wait a certain amount of time before determining the current nameserver is unresponsive, and querying the next nameserver in the /etc/resolv.conf list. That time is 15 seconds:

Code:
time dig @192.168.0.200
;; connection timed out; no servers could be reached

real    0m15.073s
With two name servers, users with misconfigured DNS servers see 30 second lags, so the 30 second delay you are experiencing is indicative.

Be sure the client can resolve the SSH server's hostname and IP as well, in similar fashion.

I believe you had said 30 seconds originally, so this was the key I used for diagnosis. Now you say 9 or 10 seconds.

Perhaps it will be useful to clarify your client and network configuration hardware and IP information.

Last edited by Mr. C.; 08-25-2008 at 10:43 PM.
 
Old 08-25-2008, 11:06 PM   #7
davidstvz
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Quote:
Originally Posted by Mr. C. View Post
With two name servers, users with misconfigured DNS servers see 30 second lags, so the 30 second delay you are experiencing is indicative.

Be sure the client can resolve the SSH server's hostname and IP as well, in similar fashion.

I believe you had said 30 seconds originally, so this was the key I used for diagnosis. Now you say 9 or 10 seconds.

Perhaps it will be useful to clarify your client and network configuration hardware and IP information.
I assume I was using dig correctly. In any case here is the typical behavior:

No one is using the server.

I go to log on and it takes a seemingly random amount of time for the login prompt to appear (it may be half a second, it may be as long as 10 seconds or even 15, but certainly not 30). If I stop using the SSH terminal for a minute or more (say to go to LinuxQuestions.org) and then go back to it, it often takes a long time to respond.

I have to say, it doesn't seem to be taking a long time to respond from my house. But from my computer at work... maybe that one is setup badly. Or maybe our primary DNS server is having trouble right now, but those other servers are fine... hmm.
 
Old 08-25-2008, 11:14 PM   #8
davidstvz
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I copied the resolv.conf file from the other server (and it was quite different than I expected) but that didn't help.

I'll use the servers more tomorrow (of course) and get an idea of whether that helped or not. Sometimes it's hard to tell without really using the thing.
 
Old 08-26-2008, 12:14 AM   #9
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Ok. Show actual data whenever possible, which is necessary for accurate, efficient diagnosis.
 
Old 08-26-2008, 03:48 PM   #10
davidstvz
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At a glance, this is definitely working properly now. The login prompt still isn't immediate, but I haven't seen the "up to ten second" times I mentioned before. What lag there is is likely because it's being used so infrequently that it goes out of memory. The ssh connections are now returning from dormancy immediately, and that was definitely my primary concern as I was sure to get ceaseless complaints about it (not to mention it was annoying me as well)

Thanks!
 
Old 08-26-2008, 04:44 PM   #11
Mr. C.
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Quote:
Originally Posted by davidstvz View Post
What lag there is is likely because it's being used so infrequently that it goes out of memory.
Unless your systems are starved for memory, the above description isn't happening.

Anyway, glad it is resolved for now.
 
Old 08-27-2008, 01:54 AM   #12
davidstvz
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Your instincts are right. The above is not happening. Editing the resolv.conf file did not help at all. The problem lies elsewhere.

It's so strange. The server remains responsive if you consistently use the ssh connection, but if you leave it alone for a minute, or try to start a new one, it's nearly random. Sometimes you get an immediate response, sometimes you wait a few seconds or several.
 
  


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