Posted by Gordon Burditt on 11/18/05 05:36

>On 'sub1.othercompany.com' there is a simple php file with an include that
>calls a script on my company's server 'sub2.mycompany.com'

Why do people do this? It seems terribly risky.

>The script on my company's server seems to work fine when I test it alone in
>the browser(it generates some xml) but when I attempt to call it from the
>other companies server as an include, I cannot access it. I *can* get to it
>from the include when I use the IP address.

If the include works with an IP address and not with a hostname,
all other things being equal, including the PHP running on the same
server both times, you have a DNS problem of some sort.
You've also eliminated a number of issues regarding allowing
remote urls and safe mode.

One possibility to consider is that the host name and the IP address
do not point to the same place. Another possibility is that if the
DNS for the host name just changed, it might be out of date on the
servers the PHP host is running on. (Allow at least 4 days for changes
to take - and no, I really don't care that YOU always observe changes
to mycompany.com DNS take in under 60 seconds. The rest of the world
doesn't use your DNS servers to do all their queries.)

>According to my company's IT guy there are no issues with our DNS. According
>to the other company they are not restricting outbound access to
>'sub2.mycompany.com'.

If you can get to it by IP address, the other company's guy is right.

> Testing something along the lines of:
>$socket = fsockopen ($Connection, $Port, $errno, $errstr, $Timeout);
>print "Error $errno: $errstr";
>
>gives:
>
>Warning: fsockopen() [function.fsockopen]: php_network_getaddresses:
>getaddrinfo failed: No address associated with hostname in
>/usr/local/www/sub1.othercompany.com/xml/socket_test.php on line 25


1. Find out what's in /etc/resolv.conf on the PHP server - which
DNS servers it's using.
2. Ask *THOSE* servers for the IP address of sub2.mycompany.com.
dig @hosting.company.dns.server sub2.mycompany.com
Do you get the correct answer from all of them?

It sounds like the complaint is (a) the domain doesn't exist, or
(b) the host doesn't exist (has no A record or CNAME record, or
the CNAME record points to someplace nonexistent), or (c) the
PHP host has broken DNS configuration and can't resolve *any*
hostnames (unlikely, as the web server would likely complain).

Another thing to do is to trace the DNS all the way from the root.
If the registration for mycompany.com expired and Network Solutions
turned it off, and you host your own DNS locally, you might not
notice the problem, since it works for you, but not for the rest
of the world. The same thing happens if the officially registered
servers for the domain point at the wrong place.

>Warning: fsockopen() [function.fsockopen]: unable to connect to
>sub2.mycompany.com:80 (Unknown error) in
>/usr/local/www/sub1.othercompany.com/xml/socket_test.php on line 25
>
>Any thoughts on the issue? Are there any diagnostic methods I can use to
>troubleshoot what the issue is?

Gordon L. Burditt

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