[Dnsmasq-discuss] No more random source port

[Albert ARIBAUD]

Hi Risto,

Le Mon, 20 Mar 2017 19:33:01 +0200
Risto Suominen <risto.suominen at gmail.com> a écrit:

> Hi,
> 
> I'm running Lubuntu 16.04 with dnsmasq 2.75-1ubuntu0.16.04.1 under
> NetworkManager's control.
> 
> When forwarding DNS requests, dnsmasq uses same source port (per
> interface) every time.
> 
> Compared to Ubuntu 14.04 with dnsmasq 2.68-1ubuntu0.1, which used
> different ports.
> 
> The command line options for dnsmasq have not changed between these
> versions, and there is no config file either.
> 
> So, I wonder, is there some change in dnsmasq itself that could
> explain this behaviour change?

I don't kow about dnsmasq per se, but the range of ports an application
can use is controlled by the kernel -- on my 16.04 Xubuntu, that is
defined by /proc/sys/net/ipv4/ip_local_port_range. Does your system
limit this range?

> My problem is that my 4G router (TP-Link TL-MR6400) won't answer to
> the requests coming from same port.

Not sure what you mean exactly. "Same port" as what?

> Risto

Amicalement,
-- 
Albert.