Services going down

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#1 Sun, 08/27/2006 - 20:37
LarryDavidson

Services going down

Hello, I have services that have gone down, such as the websites I have installed using Virtualmin, but can't find where in Virtualmin to start them. I installed 4 websites yesterday and three of them are down today. Help on how to start them using Virtualmin would be appreciated.

Sun, 08/27/2006 - 22:39
Joe
Joe's picture

Hey Larry,

If you click on "Virtualmin Menu" in the left hand menu, you'll see start buttons for all services, including Apache. But that isn't the source of your trouble if any website is still working, though I don't know what is. I'm actually suspecting maybe you're seeing a problem entirely different than what you think you're seeing...if Apache is up for one site, it's up for all of them. It doesn't run separate instances for each domain. So, we're probably seeing a problem with DNS configuration, or something else.

We need to see some Apache logs to figure if Apache is having troubles (seems unlikely if any of them are working):

Restart Apache (use the button in Virtualmin or browse to "Webmin:Servers:Apache Webserver" and restart it there), and then have a look at the last 20 lines or so of the error_log:

tail -20 /var/log/httpd/error_log

This might give us a clue of what's going wrong. Send it on to the forum and we'll see if we can spot anything.

From there, make sure DNS is doing what you expect it to do for each problem domain:

host problem.domain.com

(Where problem.domain.com should be replaced with the name of the site you're having trouble with.)

The IP that is returned should match your server. If it doesn't, it's probably the source of our trouble.

I'm not sure where else we ought to be looking for trouble...we'll need some more information to proceed.

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Mon, 08/28/2006 - 19:02
LarryDavidson

Hello Joe,
Thanks for the reply. Restarted Apache and here is a copy of the error_log.

[[root@server ~]]# tail -20 /var/log/httpd/error_log
Cannot find module (LM-SENSORS-MIB): At line 0 in (none)
Cannot find module (IPV6-ICMP-MIB): At line 0 in (none)
Cannot find module (IPV6-MIB): At line 0 in (none)
Cannot find module (IPV6-TCP-MIB): At line 0 in (none)
Cannot find module (IPV6-UDP-MIB): At line 0 in (none)
Cannot find module (SNMP-VIEW-BASED-ACM-MIB): At line 0 in (none)
Cannot find module (SNMP-COMMUNITY-MIB): At line 0 in (none)
Cannot find module (UCD-DLMOD-MIB): At line 0 in (none)
Cannot find module (SNMP-FRAMEWORK-MIB): At line 0 in (none)
Cannot find module (SNMP-MPD-MIB): At line 0 in (none)
Cannot find module (SNMP-USER-BASED-SM-MIB): At line 0 in (none)
Cannot find module (SNMP-NOTIFICATION-MIB): At line 0 in (none)
Cannot find module (SNMPv2-TM): At line 0 in (none)
[[Mon Aug 28 18:24:46 2006]] [[notice]] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[[Mon Aug 28 18:24:46 2006]] [[notice]] Digest: generating secret for digest authentication ...
[[Mon Aug 28 18:24:46 2006]] [[notice]] Digest: done
[[Mon Aug 28 18:24:46 2006]] [[notice]] LDAP: Built with OpenLDAP LDAP SDK
[[Mon Aug 28 18:24:46 2006]] [[notice]] LDAP: SSL support unavailable
[[Mon Aug 28 18:24:47 2006]] [[notice]] mod_python: Creating 4 session mutexes based on 256 max processes and 0 max threads.
[[Mon Aug 28 18:24:47 2006]] [[notice]] Apache/2.0.53 (Fedora) configured -- resuming normal operations

When I tried the host.problem.domain.com to check the DNS of the domains, I get this

[[root@server ~]]# host reval8r.com
;; connection timed out; no servers could be reached
[[root@server ~]]# host russianheartseekers.com
russianheartseekers.com has address 38.118.74.128

The second site is running but the first does not. I can't see anything in the DNS wrong with the first site. I worked when I first migrated it into Virtualmin and then stopped. I'm just not sure why.

larry

Mon, 08/28/2006 - 19:47 (Reply to #3)
Joe
Joe's picture

<i>When I tried the host.problem.domain.com to check the DNS of the domains, I get this

[[root@server ~]]# host reval8r.com
;; connection timed out; no servers could be reached
[[root@server ~]]# host russianheartseekers.com
russianheartseekers.com has address 38.118.74.128

The second site is running but the first does not. I can't see anything in the DNS wrong with the first site. I worked when I first migrated it into Virtualmin and then stopped. I'm just not sure why.</i>

DNS is your problem, specifically you're glue records at your registrar are wrong.

DNS is answering correctly when I query your server directly:

[[joe@delilah ~]]$ host reval8r.com russianheartseekers.com
Using domain server:
Name: russianheartseekers.com
Address: 38.118.74.128#53
Aliases:

reval8r.com has address 38.118.74.129
Using domain server:
Name: russianheartseekers.com
Address: 38.118.74.128#53
Aliases:

Using domain server:
Name: russianheartseekers.com
Address: 38.118.74.128#53
Aliases:

reval8r.com mail is handled by 0 reval8r.com.

But whois says your NS servers are dns3.russianheartseekers.com and dns4.russianheartseekers.com, but these servers don't exist:

[[joe@delilah dofus]]$ host dns4.russianheartseekers.com
Host dns4.russianheartseekers.com not found: 3(NXDOMAIN)
[[joe@delilah dofus]]$ host dns3.russianheartseekers.com
Host dns3.russianheartseekers.com not found: 3(NXDOMAIN)

You can do either of the following to fix it:

[list]

[*]Change the glue records to point to existing servers[/*]

[*]Add records for those two addresses in the russianheartseekers.com zone pointing to valid DNS servers that have accurate data for your reval8r.com domain[/*]

[/list]

Virtualmin is orthogonal to this problem (i.e. it has nothing to do with it). It's likely that the problem has existed for a few days, and only now has your local DNS cache caught up to the incorrect information.

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Mon, 08/28/2006 - 21:54
LarryDavidson

Hello Joe,
I changed the DNS for this site back to my old server which is the 38.118.74.128. I was wanting to move my sites to the new server, but it's not going so well. This site will have to stay on the old server until I get the new one with Virtualmin stable and running, I can't afford for it to go down.

I have four sites that will be on the new server, but for some reason can only get one at a time to work.

Thanks for the help Joe.

Tue, 08/29/2006 - 01:13 (Reply to #5)
Joe
Joe's picture

Hey Larry,

<i>I changed the DNS for this site back to my old server which is the 38.118.74.128. I was wanting to move my sites to the new server, but it's not going so well. This site will have to stay on the old server until I get the new one with Virtualmin stable and running, I can't afford for it to go down.</i>

That doesn't change the fact that the glue records at your registrar were pointing to non-existent names (non-existent on the new server), when I checked them. I'm almost certain that's the entire source of your trouble, and it is easily corrected.

The new whois record is still pointing to non-existent servers (in addition to the old non-existent servers):

[[joe@delilah installer]]$ host dns1.russianheartseekers.com
Host dns1.russianheartseekers.com not found: 3(NXDOMAIN)
[[joe@delilah installer]]$ host dns2.russianheartseekers.com
Host dns2.russianheartseekers.com not found: 3(NXDOMAIN)

This just can't possibly work (though you may have cached DNS information in your local resolver that makes it look like it's working for you). And, as expected, it doesn't resolve for me:

[[joe@delilah installer]]$ host reval8r.com
Host reval8r.com not found: 2(SERVFAIL)
[[joe@delilah installer]]$ host www.reval8r.com
Host www.reval8r.com not found: 2(SERVFAIL)

<i>I have four sites that will be on the new server, but for some reason can only get one at a time to work.</i>

We can test it without having to have regular users pointing to it. We need to isolate down what the real problem is--it's just not possible for &quot;one at a time to work&quot;, under any scenario I can imagine. ;-)

What is the address of the new server? I'd like to poke at the DNS and website, as it exists on the new server, by pointing my hosts file to the new server--this allows me to figure out which part of the system isn't doing what it ought to be. The details I have, so far, of the trouble really gives me nothing to go on.

DNS problems of this sort often exhibit themselves in just this way--it works sometimes, doesn't work other times. This is because of the caching and seamlessly distributed nature of DNS service. If your ISP has two name servers, one of them might have cached working data, while the other may not...so sometimes you'd get good results, while others you wouldn't. Your local machines resolver would also have a cache of the data, further confusing the issue.

The more tidbits I hear about the problem, the more likely it seems that it is entirely DNS misconfiguration. Fix the DNS stuff, and I'm betting that everything will look much more &quot;stable&quot;.

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Tue, 08/29/2006 - 16:20
LarryDavidson

Thanks for the help Joe. It was just easier for me to delete everything I had and start over. After migrating the sites again, they are working.