Hi,
I've successfully set up Asterisk on OpenWrt (master build 18376 on EdgeRouter X SFP) for the VoiP service of the German provider 1&1. However, there is one issue regarding the configuration of the firewall: without any port forwarding only some incoming calls come thru, others are not, totally random. I've found out, that 1&1 seems to use two servers for VoiP UDP as some sort of load balancing, I think. The problem is, that those servers are using two different ip addresses. If now an incoming packet is coming from the ip, which is not the one, my asterisk server is connected to, the firewall doesn't have this ip in its state table and the packets are dropped. Currently, to workaround this, I have set up a traffic rule for those two ips, which works so far. However, I would like to ask, if there are any recommendations, how to set up the firewall in such cases?
These are the servers, 1&1 is providing:
$ dig _sip._udp.sip.1und1.de SRV
[…]
;; ANSWER SECTION:
_sip._udp.sip.1und1.de. 86400 IN SRV 0 0 5060 1und1-2.sip.1und1.de.
_sip._udp.sip.1und1.de. 86400 IN SRV 0 0 5060 1und1-1.sip.1und1.de.
[…]
=================
$ dig 1und1-1.sip.1und1.de
[…]
;; ANSWER SECTION:
1und1-1.sip.1und1.de. 6903 IN A 212.227.124.130
1und1-1.sip.1und1.de. 6903 IN A 212.227.124.129
[…]
=================
$ dig 1und1-2.sip.1und1.de
[…]
;; ANSWER SECTION:
1und1-2.sip.1und1.de. 6889 IN A 212.227.124.129
1und1-2.sip.1und1.de. 6889 IN A 212.227.124.130
[…]
config rule
list proto 'udp'
option target 'ACCEPT'
option family 'ipv4'
list src_ip '212.227.124.129'
list src_ip '212.227.124.130'
option src_port '5060'
option name 'Allow 1und1 SIP'
option src 'wan'
option dest_port '5060'
If further info is needed, please ask.
Thanks for any remarks and tips on this!