Hi All
Just to dive in here with something which may be related. I was about to do a post with a much simpler problem where I have one real NIC and one VPN created NIC. If I listen to the public IP all’s well. If I listen to the IP of the VPN NIC Kamailio doesn’t see any traffic. I can tcpdump on either NIC and see the traffic arriving.
Anyone seen / solved this before?
Cheers Mark
On 11 Oct 2017, at 22:07, George Diamantopoulos georgediam@gmail.com wrote:
Hello Daniel,
I'm including the original sketch for clarity:
+----------+ +-------------------+ | eth0 | | vrf-green | | 1.1.1.1 | | 127.0.0.1 | +----------+ +-------------------+ | +----------+ | eth1 | | 2.2.2.2 | +----------+
Thanks for the reply. Indeed, using the advertise option for the "listen" directive will result in kamaiio no longer failing to start when using force_send_socket(2.2.2.2:5060 http://2.2.2.2:5060/) with 2.2.2.2 being used in the "advertise" option.
However, this doesn't make much of a difference in that kamailio still won't process IP packets arriving on eth1 at IP 2.2.2.2... I can see OPTIONS coming with sngrep, but nothing in the logs, no replies, only retransmissions from the originator. In addition, while without VRF kamailio will select the right interface with mhomed=1, this is no longer the case. Also, If I try to send something to a host with force_send_socket, the transaction fails with 477 Unfortunately error on sending to next hop occurred. In the log, kamailio prints something along the lines of: udp_send(): sendto(sock,0x7f5c4f937d08,1888,0,9.9.9.9:5060 http://9.9.9.9:5060/,16): Invalid argument(22) udp_send(): invalid sendtoparameters msg_send_buffer(): udp_send failed where 9.9.9.9 is the $dd and presumably force_send_socket(2.2.2.2:5060 http://2.2.2.2:5060/) has been called before t_relay()
Also, I additionally found out that if the networking configuration is as follows:
+----------+ +-------------------+ +-------------------+ | eth0 | | vrf-green | | vrf-red | | 1.1.1.1 | | 127.0.0.1 | | 127.0.0.1 | +----------+ +-------------------+ +-------------------+ | | +----------+ +----------+ | eth1 | | eth2 | | 2.2.2.2 | | 3.3.3.3 | +----------+ +----------+
Then this won't work for vrf-red: listen=vrf-green:5060 advertise 2.2.2.2:5060 http://2.2.2.2:5060/ listen=vrf-red:5060 advertise 3.3.3.3:5060 http://3.3.3.3:5060/ One needs to use different IPs for the MASTER devices (say 127.0.0.1 and 127.0.0.2) for kamailio to startup with the above listen directives.
It's a bit surprising it doesn't work. According to a user on cumulus slack channel (cumulus contributed the VRF code to the linux kernel): "any app that has a command line or option switch to call SO_BINDTODEVICE on the sockets can be configured to use any VRF".
I guess the problem lies in that kamailio binds to several sockets and there are multiple routing tables to consult, so mhomed doesn't work as expected (if every table has a default route and nothing more specific than that). But still, this doesn't really explain why binding to the VRF master net devices doesn't work (I mean, "ping -I vrf-green" works just fine for ping)...
I don't think VRF support is very useful for most users though, I just had one corner case I needed to tackle and VRF seemed like an easy fix. I'll think of an alternative at some point, I guess.
On 26 September 2017 at 09:52, Daniel-Constantin Mierla <miconda@gmail.com mailto:miconda@gmail.com> wrote:
Hello,
I haven't worked with vrf here, so no first hand experience ...
What happens if you try with next option?
listen=vrf-green:5060 advertise 2.2.2.2:5060 http://2.2.2.2:5060/
Cheers, Daniel
On 25.09.17 19:10, George Diamantopoulos wrote:
Sorry to bump this, but it would be very useful if I knew whether there's any point in pursuing this or not. Any hints?
On 21 September 2017 at 14:06, George Diamantopoulos <georgediam@gmail.com mailto:georgediam@gmail.com> wrote:
Hello,
I have a use case where I need to have kamailio bind to a VRF device. The configuration in question is similar to the example below, where eth1 is a slave to the VRF-lite device:
+----------+ +-------------------+ | eth0 | | vrf-green | | 1.1.1.1 | | 127.0.0.1 | +----------+ +-------------------+ | +----------+ | eth1 | | 2.2.2.2 | +----------+
Both the main routing table and "vrf-green" routing table have a default route.
What I need to be able to do is have kamailio bind to both interfaces:
listen=eth0:5060 listen=vrf-green:5060
And additionally be able to use force_send_socket to select an interface, for example:
force_send_socket(udp:2.2.2.2:5060 http://2.2.2.2:5060/);
However, I can't get this to work. The above configuration fails because there is no listen directive for 2.2.2.2. Also, kamailio doesn't process packets received on the VRF with the above listen directives, it behaves as if it doesn't listen on 2.2.2.2 indeed.
In addition using either of the below:
listen=udp:2.2.2.2:5060 http://2.2.2.2:5060/ or listen=eth1:5060
fails with an error upon starting kamailio.
According to the kernel documentation:
Applications that are to work within a VRF need to bind their socket to the VRF device:
setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, dev, strlen(dev)+1);or to specify the output device using cmsg and IP_PKTINFO.
The question is, is VRF useable with kamailio right now? Or is development needed? Thanks!
BR,
George
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