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From Jim Albert <...@netrition.com>
Subject Re: automatically restart httpd
Date Tue, 23 Apr 2013 19:09:33 GMT
On 4/23/2013 2:33 PM, Ryan Perry wrote:
>
>
>
> On Tue, Apr 23, 2013 at 12:47 PM, Jim Albert <jim@netrition.com
> <mailto:jim@netrition.com>> wrote:
>
>     On 4/23/2013 1:36 PM, Ryan Perry wrote:
>
>
>
>
>         On Tue, Apr 23, 2013 at 12:23 PM, Jim Albert <jim@netrition.com
>         <mailto:jim@netrition.com>
>         <mailto:jim@netrition.com <mailto:jim@netrition.com>>> wrote:
>
>              On 4/23/2013 1:08 PM, Ryan Perry wrote:
>
>                  I've considered doing it daily via cron, but if there's
>         a way to
>                  do when
>                  I hit this error I'd prefer that.
>
>
>                  On Tue, Apr 23, 2013 at 12:02 PM, Jim Albert
>         <jim@netrition.com <mailto:jim@netrition.com>
>                  <mailto:jim@netrition.com <mailto:jim@netrition.com>>
>                  <mailto:jim@netrition.com <mailto:jim@netrition.com>
>         <mailto:jim@netrition.com <mailto:jim@netrition.com>>>> wrote:
>
>                       On 4/23/2013 11:49 AM, Ryan Perry wrote:
>
>                           I've been plagued by some bug that makes a
>         call to LWP
>                  stop working:
>                           "Can't connect to 192.168.0.222 (Bad hostname)"
>
>                           I haven't been able to figure out why, but a
>         simple httpd
>                           restart fixes
>                           it for a day or 2.
>
>                           Since I can't figure out a real fix, I'm
>         wondering if
>                  there is a
>                           way for
>                           me to automatically restart httpd whenever the bug
>                  hits.  Maybe
>                           whenever
>                           it appears in the httpd-error.log?  What are
>         my options?
>
>
>                       Without more to go on to the actual cause of the
>         problem...
>
>                       Restarting apache daily isn't a bad idea in
>         general if even
>                  just a
>                       graceful restart.
>                       kill -USR1 `cat /var/run/httpd.pid`
>                       which I believe should be safe any time of day.
>
>                       If a complete restart, maybe early morning off hours
>                  assuming your
>                       server requires a high degree of availability?
>
>                       Jim
>
>
>              Try to remember not to top-post, please. It makes it hard
>         for others
>              to read the thread.
>
>              I don't know, but it kind of has a DNS feel to it,
>         possibly. Nothing
>              concrete to go on, just past experience when I see network
>         and I
>              know the network is fine... I think DNS. Maybe reverse
>         resolution of
>              your private IP address space assuming your requests are
>         being made
>              to/from private addresses? That's really just a shot in the
>         dark
>              because we don't have much to go on. I'd start thinking
>         network and
>              DNS, put in some debug, see what if anything is timing out.
>
>              Jim
>
>
>         Sorry about the top post.
>
>         I've done the debugging on DNS.  If it try changing the
>         IP/hostname I
>         still get the error.  I think it's per-process though.  Once it
>         starts
>         to happen it's intermittent and gets worse, making me think
>         depending
>         which process I hit it will work or not until all processes are
>         affected.
>
>         This is on FreeBSD using a jailed (virtualized) host.  I read about
>         apache/jails on OpenBSD having a config issue with DNS but it seemed
>         different than this.
>
>         It only seems to affect httpd, I can log in and ping from the server
>         just fine.
>
>
>     Also, please reply to the list, not personal email addresses so
>     everyone else gets the benefit of the thread, and maybe you get a
>     better answer from someone other than me. :)
>
>     I'm not so sure you've eliminated DNS, yet.
>
>     What if from 192.168.0.222 you:
>     dig -x 192.168.0.x
>
>     where 192.168.0.x is the IP addressing making the connection to
>     192.168.0.222
>
>     Do you have reverse resolvers for your private address space or are
>     the requests handled by the top level root servers?
>
>     Who is answering for that reverse resolution request?
>     dig -x 192.168.0.x
>     Is it your resolver or a root level like prisoner.iana.org
>     <http://prisoner.iana.org>
>
>     Jim
>
>
> Interesting, but it seems hard to believe that would be it.  I don't
> have any other suspects though...
>
>
> ; <<>> DiG 9.8.3-P3 <<>> -x 192.168.0.200
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20209
> ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
>
> ;; QUESTION SECTION:
> ;200.0.168.192.in-addr.arpa.INPTR
>
> ;; AUTHORITY SECTION:
> 168.192.in-addr.arpa.10800INSOAlocalhost. nobody.invalid. 1 3600 1200
> 604800 10800
>
> ;; Query time: 6 msec
> ;; SERVER: 4.2.2.1#53(4.2.2.1)
> ;; WHEN: Tue Apr 23 18:28:37 2013
> ;; MSG SIZE  rcvd: 103
You're using a public resolver... 4.2.2.1
I'm not saying that's your problem, but I've had problems in the past 
where connections were slow or timed out doing a reverse lookup of my 
private address space. The problem went away after configuring my own 
resolvers to handle reverse lookups on my private address space.

If you want to continue to use 4.2.2.1 or any public resolver as your 
resolver, that's not an option.

If you have your own resolvers, this might help:
http://www.sendmail.com/sm/open_source/tips/private_dns/

Again... I'm still kind of shooting in the dark, so my confidence level 
on where I'm going with this is not high.

You really should put some debug in or maybe a packet trace... is your 
server actually getting the request is where I would start.

Does your ISP provide a resolver? Is there a reason you want to use 
4.2.2.1 rather than your ISP's or your own or maybe at least Google's at 
8.8.8.8?

Jim


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