blog:apache_redhat_6_make_sock_bug [DBZoo]

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====== Apache Redhat 6 make_sock Apache defect ======

This is a fucker of a defect that affected RedHat 6.3, 6.4, 6.5 - which I've verified.  Probably 6.0, 6.1, 6.2 and 6.3 as well.
I found this: https://issues.apache.org/bugzilla/show_bug.cgi?id=45863 but it was of no help and was more of a red-herring than anything else.

<code>
# httpd -version
Server version: Apache/2.2.23 (Unix)
Server built:   Feb 13 2013 02:41:10
</code>

Here is the output that you are confronted with
<code>
[Thu Sep 19 14:11:13 2013] [warn] VirtualHost localhost:82 overlaps with VirtualHost localhost:82, the first has precedence, perhaps you need a NameVirtualHost directive
[Thu Sep 19 14:11:13 2013] [warn] VirtualHost localhost:81 overlaps with VirtualHost localhost:81, the first has precedence, perhaps you need a NameVirtualHost directive
(98)Address already in use: make_sock: could not bind to address 127.0.0.1:81
no listening sockets available, shutting down
Unable to open logs
</code>

Doing an lsof, netstat, telnet or anything else you can think of on port 81 tells you nothing is listening.  OK so why the error message !

The strace is telling its trying to bind TWICE to the same port!  WTF.
<code>
32709 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
32709 setsockopt(3, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
32709 setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
32709 bind(3, {sa_family=AF_INET, sin_port=htons(81), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
32709 listen(3, 511)                    = 0
32709 setsockopt(4, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
32709 setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
32709 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0
32709 bind(4, {sa_family=AF_INET, sin_port=htons(81), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EADDRINUSE (Address already in use)
</code>

The solution.  The trouble makers were found in /etc/hosts as follows
<code>
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
</code>
Once we had removed 'localhost' and 'localhost.localdomain' from the ::1 definition line, apache/httpd could start successfully.

UPDATE: In light of https://issues.apache.org/bugzilla/show_bug.cgi?id=52884

In my configuration I had this
<code>
Listen localhost:81
</code>
If I had change it to this it would have also made the problem go away.
<code>
Listen 127.0.0.1:81
</code>

{{tag>apache}}

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