Re: client socket and source port selection

[Roberto Nibali]

Hello,

> For the project i'm doing, i must know how the Linux kernel allocate
> sockets source port (from the dynamic range of the (2**16)-1 ports). I
> looked on the Web but it's really hard to find the algoritm of the
> source port allocation...

Check the source ;). There is a proc-fs entry which relates to the 
source port range setting. Over this entry point you get in case of TCP 
sockets to ../net/ipv4/tcp_ipv4.c:tcp_v4_get_port(...). For UDP sockets 
you need to peek into ../net/ipv4/udp.c:udp_v4_get_port().

> Someone maybe know how it's work or if there is a paper on the web that
> explain this source port selection ?

Not likely, but reading the source should help. You can set the local 
port range via /proc/sys/net/ipv4/ip_local_port_range. It's documented.

HTH and best regards,
Roberto Nibali, ratz
--
echo 
'[q]sa[ln0=aln256%Pln256/snlbx]sb3135071790101768542287578439snlbxq' | dc
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