❦ 23 février 2014 12:25 CET, Willy Tarreau <[email protected]> :
>> I suppose this is in combination with SO_REUSEADDR (otherwise, bind()
>> would fail). It's good to know:
>>
>> tcp ESTAB 0 0 192.168.116.1:37544 74.125.132.104:80
>>
>> tcp ESTAB 0 0 192.168.116.1:37544 74.125.132.106:80
>>
>
> You don't even need SO_REUSEADDR nor SO_REUSEPORT for this. This is
> standard. For example, FTP servers in active mode all need to bind
> to source port 20 and connect to the remote.
I just tried this on Linux 3.12:
In [69]: s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
In [70]: s2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
In [71]: s1.bind(("0.0.0.0", 37546))
In [72]: s2.bind(("0.0.0.0", 37546))
---------------------------------------------------------------------------
error Traceback (most recent call last)
<ipython-input-72-9d64edf0584f> in <module>()
----> 1 s2.bind(("0.0.0.0", 37546))
/usr/lib/python2.7/socket.pyc in meth(name, self, *args)
222
223 def meth(name,self,*args):
--> 224 return getattr(self._sock,name)(*args)
225
226 for _m in _socketmethods:
error: [Errno 98] Address already in use
>> As for getting the same stuff without explictely use bind(), I just
>> tried with a 3.2 and I am able to get in the same situation without
>> bind() nor SO_REUSEADDR option:
>>
>> tcp ESTAB 0 0 10.234.78.65:61000 10.234.78.67:80
>>
>> tcp ESTAB 0 0 10.234.78.65:61000 10.234.78.66:80
>>
>
> OK so it confirms that it's really 3.2 which first worked on this.
I am too lazy to find the first kernel which works. Looking at the
commits, I have found 2b05ad (tcp: bind() fix autoselection to share
ports) which may fit the description but it appears in Linux 3.3-rc2 and
was not backported to 3.2 stable. So, my best guess is fda48a (tcp:
bind() fix when many ports are bound) but it appeared in 2.6.34-rc6.
--
Don't over-comment.
- The Elements of Programming Style (Kernighan & Plauger)
