Re: [Openvpn-users] No traffic beyond the server from the client ...

[Erich Titl <erich.titl@xxxxxxxx>]

Niclas

Lists Soderlund.org wrote:

> Erich Titl wrote:
>
> > Niclas
> >
> > Lists Soderlund.org wrote:
> >
> > > ...
> > > Hi!
> > >
> > > Oops, actually, I was just testing at the moment, and when I changed 
> > > that back this is what I get instead for a routingtable (still the 
> > > same problem, no traffic is forwarded or at least not responded to):
> > >
> > > dns:/etc/openvpn# route
> > > Kernel IP routing table
> > > Destination     Gateway         Genmask         Flags Iface
> > > 10.0.0.2        *               255.255.255.255 UH    tun0
> > > 213.214.236.80  *               255.255.255.240 U     eth0
> > > 10.0.0.0        10.0.0.2        255.255.255.0   UG    tun0
> >
> >
> >
> > OK, looks like you are routing 10.0.0.0 to tunnel tun0 and (above) 
> > 10.0.0.2
> >
> > IIRC you observe (using tcpdump on tun0)  the packets arriving at the 
> > server.
> >
> > I assume 213.214.236.80 is the network you want to route to?
> >
> > Would you mind to post the tcpdump output for tun0 and eth0 during 
> > the tests
> >
> > cheers
> >
> > Erich
>
> Hi!
>
> Here is the dumps. The packets obviously comes thru the tunnel to the 
> server. However, no answer is submitted back thru the tunnel to the 
> client.
>
> dns:~# tcpdump -i tun0
> tcpdump: WARNING: arptype 65534 not supported by libpcap - falling 
> back to cooked socket
> tcpdump: verbose output suppressed, use -v or -vv for full protocol 
> decode
> listening on tun0, link-type LINUX_SLL (Linux cooked), capture size 96 
> bytes
> 14:21:36.609795 IP 192.168.10.6 > www.sunet.se: icmp 40: echo request 
> seq 14080
> 14:21:44.519248 IP 192.168.10.6 > www.sunet.se: icmp 40: echo request 
> seq 14336
> 14:21:49.629102 IP 192.168.10.6 > www.sunet.se: icmp 40: echo request 
> seq 14592

luna > ping www.sunet.se
PING www.sunet.se (192.36.125.18) 56(84) bytes of data.
64 bytes from www.sunet.se (192.36.125.18): icmp_seq=1 ttl=244 time=46.0 ms
64 bytes from www.sunet.se (192.36.125.18): icmp_seq=2 ttl=244 time=44.6 ms

OK www.sunet.se obviously accepts icmp echo requests.

> 3 packets captured
> 3 packets received by filter
> 0 packets dropped by kernel
> dns:~#
>
> dns:~# tcpdump -i eth0 udp port 1194
> 14:20:13.571145 IP ns.soderlund.org.openvpn > 
> the_client.gateway.outside.firewall.ipadress.48636: UDP, length: 53
> 14:20:13.591062 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 53
> 14:20:23.690858 IP ns.soderlund.org.openvpn > 
> the_client.gateway.outside.firewall.ipadress.48636: UDP, length: 53
> 14:20:23.710342 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 53
> 14:20:29.550462 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 101
> 14:20:33.810295 IP ns.soderlund.org.openvpn > 
> the_client.gateway.outside.firewall.ipadress.48636: UDP, length: 53
> 14:20:35.020621 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 101
> 14:20:35.462749 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 85
> 14:20:38.415047 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 85
> 14:20:40.026444 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 101
> 14:20:40.479712 IP the_client.gateway.outside.firewall.ipadress.48636 
> > ns.soderlund.org.openvpn: UDP, length: 85

I see here that you filter the openvpn port in your tcpdump. I am mostly 
interested in the ICMP packets which should be sent through this 
interface to www.sunet.se. Do you see those packets on this interface? 
If so, what is the  source address of this packets?

cheers

Erich


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