Issue #9544 has been updated by Jakub Szafranski.


<pre># ruby -rsocket -e '10.times { p Addrinfo.udp("0.0.0.0", 0).bind.local_address }'
#&lt;Addrinfo: 0.0.0.0:65533 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65532 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65531 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65530 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65529 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65528 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65527 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65526 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65525 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65524 UDP&gt;</pre>

BUT:

<pre># sysctl -w net.inet.udp.rfc6056.selected=random_pick
net.inet.udp.rfc6056.selected: bsd -> random_pick
# ruby -rsocket -e '10.times { p Addrinfo.udp("0.0.0.0", 0).bind.local_address }'
#&lt;Addrinfo: 0.0.0.0:56358 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:52365 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:58857 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:53113 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:49585 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:62833 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:65299 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:53542 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:60367 UDP&gt;
#&lt;Addrinfo: 0.0.0.0:52945 UDP&gt;</pre>

<pre># uname -mrsv
NetBSD 6.1.3 NetBSD 6.1.3 (GENERIC) amd64</pre>

So basically, the system admin can change the random port alghoritm, and he can choose from a variety of alghoritms:

<pre># sysctl net.inet.udp.rfc6056.available
net.inet.udp.rfc6056.available = bsd random_start random_pick hash doublehash randinc</pre>

Once again - I really think that it's not ruby case to randomize the port - in my opinion, this should always rely on the underlying system, and such thing shouldn't be forced by the language itself.

----------------------------------------
Bug #9544: Ruby resolver not using autoport
https://bugs.ruby-lang.org/issues/9544#change-45419

* Author: Jakub Szafranski
* Status: Feedback
* Priority: Normal
* Assignee: 
* Category: core
* Target version: current: 2.2.0
* ruby -v: ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-freebsd9.1]
* Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
### Problem

On one of my production servers I've noticed that customers were failing to install anything using gem and the latest ruby. After a bit of debugging we've found out, that it's related to ruby resolve module:

<pre>
> p Resolv.getaddress "google.com"
Errno::EPERM: Operation not permitted - bind(2) for "0.0.0.0" port 62374
        from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:654:in `bind'
        from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:654:in `bind_random_port'
        from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:747:in `block in initialize'
        from /home/pudlobe/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/resolv.rb:735:in `each'
        ...
</pre>

The interesting part is _bind_random_port_ function. What for? The standard way of binding to a random port for udp connection is to use port 0. And on that particular machine it fails because it's using a mac_portacl module to filter which user can bind to what ports. **However, port 0 is excepted from this rule, because it's the AUTOPORT** - practically every system that allows such port filtering also allows to set an exception for the autoport.

### Docs

<pre>
Purpose:

Port 0 is officially a reserved port in TCP/IP networking, meaning that it should not be used for any TCP or UDP network communications. However, port 0 sometimes takes on a special meaning in network programming, particularly Unix socket programming. In that environment, port 0 is a programming technique for specifying system-allocated (dynamic) ports.
Description:

Configuring a new socket connection requires assigning a TCP or UDP port number. Instead of hard-coding a particular port number, or writing code that searches for an available port on the local system, network programmers can instead specify port 0 as a connection parameter. That triggers the operating system to automatically search for and return the next available port in the dynamic port number range.</pre>

### Impact

This bug affects every system that has a restricted port-binding policy, making ruby unavailable for security-freak admins ;)

### Suggested fix:

Either use port 0 to bind to the port, or at least make an option for the system admin/end user to specify the port by himself.




-- 
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