12 May
2023
12 May
'23
12:54 a.m.
On 11/05/2023 16.00, [EXT] Calvin E. wrote:
We added a listen on localhost and forced the outside
application
server to return 127.0.0.1 instead of the IP of Kamailio. This worked
as expected, but wasn't the solution we were looking for.
It turns out that enabling sysctl net.ipv4.ip_forward=1 resolves the
original issue. Is IP Forwarding a normal requirement for Kamailio in
general?
For reference, running "ip route get _interface_ip_" on other Linux
servers confirms that the "lo" interface is used when sending packets
to an assigned Ethernet IP address.
That is quite surprising as IP forwarding is something very much
different, and definitely shouldn't be required for normal communication
with a locally bound address (and with that communication going over the
`lo` interface being completely expected).
You mentioned the address being a floating address. Was this address
perhaps not bound when Kamailio was started? (Doing this requires the
`ip_nonlocal_bind` sysctl to be enabled, although in that case I guess
the :5060 port also wouldn't be open.)
"Port unreachable" could also indicate a REJECT firewall rule, perhaps
something restricting `lo` to be used only with localhost addresses,
and/or something restricting the external IP address only to its
respective eth interface? (Although enabling IP forwarding wouldn't
change anything in that case.)
Cheers