CentOS - Nov 2012 - Fwd: Different behavior of net.ipv4.ip_local_port_range between RHEL-5 and RHEL-6

Forwarding just in case anyone is familiar with this on CentOS, thanks!

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Hello,

Just found that net.ipv4.ip_local_port_range has different behavior
between RHEL releases: until v6 although you have multiple source IPs
you can only use a fixed number of local ports, seems that
"ip_local_port_range" is a global configuration or limitation. On
RHEL-6
kernel (testing with 2.6.32-279) you can bind() to N local ports per
source IP, it's a per-IP limit: total ports = ip_local_port_range x
source IP.

The problem is that on RHEL-5 and 4 you can only make
ip_local_port_range outgoing connections and you can't use different
source IPs trick to increase this limitation. I have been testing and
vanilla 2.6.32 kernel and other Linux distributions like Debian doesn't
support this. What has been changed/patched on RHEL-6 to allow this?

Santi Saez

On 08/11/12 08:53, Santi Saez wrote:
> Forwarding just in case anyone is familiar with this on CentOS, thanks!
Hello,

I don't know the exact bit that enables this feature in the kernel, but 
chances are the el5 kernel is simply too old to support this. If you 
want to stick with el5 then you could have a shot at it by using 
kernel-lt or kernel-ml from elrepo project.

On 11/08/2012 12:53 AM, Santi Saez wrote:
> The problem is that on RHEL-5 and 4 you can only make
> ip_local_port_range outgoing connections and you can't use different
> source IPs trick to increase this limitation.
How have you configured the system to use the additional source 
addresses for outgoing connections?