Question

I m working with an OS X 10.6 Server running Apache2 / PHP5 and having a problem with PHP not resolving hostnames when fopen() tries to retrieve a file from a remote server. When run in interactive mode on the command line fopen() works perfectly. However, when run through the web it will always fail with the error:

failed to open stream: php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known

I m at a loss in finding the source of this problem: fopen() works on the web when given an IP address instead of a hostname; gethostbyname() also fails when run on the web (it doesn t error, it just returns whatever hostname it was given to resolve) but also works fine when run in interactive mode. The only exception seems to be dns_get_record() which works fine when run on the web or in interactive mode.

I ve been trying to find DNS problems on the server but dig, nslookup, and ping all work and "scutil -r" says the remote server is reachable with the current DNS settings. Any ideas on where the problem might be?

Answer 1

Try to recompile PHP with --disable-ipv6 option. Then, apachectl stop & start (not apachectl restart ). I ve got the same error message on Mac OS 10.6.4 + manually compiled PHP5.3.3 + Apache2.2.16.

Answer 2

You must set properly the allow_url_fopen value of your php.ini.

http://ar.php.net/manual/en/filesystem.configuration.php#ini.allow-url-fopen

Consider the CLI uses a different php.ini that the webserver (I assume you are using Apache).

Another option may be you are not including libnss_dns

Try adding to your httpd configuration (correct path as needed for you system):

LoadFile /lib/libnss_dns.so

Answer 3

If you are are running PHP-FPM with chroot settings (as you should be) - then neither DNS nor mail will work.

Update Feb 2016

strace using gethostbyname only from the test-script @ https://knzl.de/setting-up-a-chroot-for-php/ solved dns for me in an Alpine Linux / nginx chroot. I also use the sh from this link with mini-sendmail to solve the mail problem.

An approximate list of files needed for DNS & Mail in a chroot

The following commands got DNS working for me with PHP5.5 on Debian (tested with the Joomla builtin update component):

#!/bin/sh

chroot=/var/www
domain=mydomain
webuser=www-data
webgroup=www-data

cd $chroot/$domain

mkdir etc

cp /etc/resolv.conf etc/
cp /etc/nsswitch.conf etc/
echo $(cat /etc/group|grep $webgroup) > etc/group
echo $(cat /etc/passwd|grep $webuser) > etc/passwd
cp /etc/services etc/
cp /etc/protocols etc/
cp /etc/host.conf etc/
cp /etc/hosts etc/
cp /etc/networks etc/

mkdir -p usr/bin   
mkdir usr/sbin

cp /usr/sbin/ssmtp usr/sbin/
cp /usr/sbin/sendmail usr/sbin/

mkdir usr/share

cp -rf /usr/share/zoneinfo usr/share

mkdir lib

cp /lib/i386-linux-gnu/libresolv.so.2 lib/
cp /lib/i386-linux-gnu/libnss_compat.so.2 lib/
cp /lib/i386-linux-gnu/libc.so.6 lib/
cp /lib/i386-linux-gnu/libnsl.so.1 lib/
cp /lib/i386-linux-gnu/libnss_files.so.2 lib/
cp /lib/i386-linux-gnu/libz.so.1 lib/
cp /lib/i386-linux-gnu/libdl.so.2 lib/
cp /lib/i386-linux-gnu/libcidn.so.1 lib/
cp /lib/i386-linux-gnu/ld-linux.so.2 lib/
cp /lib/i386-linux-gnu/libcrypt.so.1 lib/
cp /lib/i386-linux-gnu/libnss_nis.so.2 lib/
cp /lib/i386-linux-gnu/libnss_dns.so.2 lib/

chown -R $webuser:$webgroup lib usr etc
service php5-fpm restart

I did not need /bin/sh or /usr/lib/locale

Answer 4

Same problem, different solution then the original poster. I was calling mysqli(...) to connect, but the URL I had for the server was wrong. So it doesn t always mean you are unable to do any DNS lookup, just that the server that it is not able to do that specific lookup (check your host!)

Answer 5

What is the hostname you tried to resolve? I had the same problem with localhost.

This didn t worked and I got your Error. I changed the hostname to 127.0.0.1 than it worked. Not the best solution, but good for a workaround.

Answer 6

Disable IPv6 in your TCP/IP configuration in net preference.

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