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Re: OpenVPN



On Wed, Oct 28, 2009 at 06:24:05AM -0300, Daniel Bareiro wrote:
> 
> Hi all!
> 
> I was making a first attempt to establish a VPN between my house and the
> office. The scenery from the side of my house is the following one:
>                                                           ________
> +----------+     +-----------+     +----------+      ____/        \___
> | OpenVPN  |_____| GNU/Linux |_____| ADSL     |_____/     Internet    \
> | server   |     | Firewall  |     | Router   |     \____         ____/
> +----------+     +-----------+     +----------+          \_______/
> 
> Local network: 10.1.0.0/24
> VPN network:   10.8.0.0/24

any particular reason not to run the vpn server on the firewall !  it is
already the default gw for your local lan and it would make routing
easier.

what you have below is the a sympton of the routing problem.

also any reason you choose tun over tap - I usually default to tap.

Alex

> 
> In the GNU/Linux firewall configuration (using Shorewall), I only added a
> DNAT rule to the OpenVPN server. I believe that it is the unique thing that
> it would be being necessary.
> 
> Besides this, in router I added a rule doing forwarding of the
> originating traffic of its own WAN with port 1194 to the interface that
> it has in the other end that it gives with GNU/Linux firewall.
> 
> Until this instance, starting a OpenVPN client in the office I could
> verify that the tunnel is established, but I can only reach the OpenVPN
> server. The rest of hosts of my LAN is unareachables.
> 
> The following one is a capture with tcpump in the OpenVPN server when I
> doing ping from the office to one host of my house:
> 
> # 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
> 07:08:17.231084 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 47698, seq 1, length 64
> 07:08:18.233021 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 47698, seq 2, length 64
> 07:08:19.231793 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 47698, seq 3, length 64
> 
> Apparently it would be lacking some way that causes that the packages
> could return.
> 
> Then I tried adding the following thing:
> 
> * To add in my GNU/Linux firewall a rule so that all the traffic that
>   goes to the network 10.8.0.0/24 is reached through the IP of the
>   OpenVPN server:
> 
>   # route add -net 10.8.0.0 netmask 255.255.255.0 gw 10.1.0.4
> 
> * Enable forwarding in the OpenVPN server:
> 
>   # echo 1 > /proc/sys/net/ipv4/ip_forward
> 
> And I repeated the test: 
> 
> 07:13:17.213590 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 55380, seq 1, length 64
> 07:13:17.213942 IP ns1.freesoftware.org > 10.8.0.6: ICMP echo reply, id 55380, seq 1, length 64
> 07:13:18.215097 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 55380, seq 2, length 64
> 07:13:18.215433 IP ns1.freesoftware.org > 10.8.0.6: ICMP echo reply, id 55380, seq 2, length 64
> 07:13:19.215920 IP 10.8.0.6 > ns1.freesoftware.org: ICMP echo request, id 55380, seq 3, length 64
> 07:13:19.216272 IP ns1.freesoftware.org > 10.8.0.6: ICMP echo reply, id 55380, seq 3, length 64
> 
> This way already I could reach with ping/nmap at the other hosts from the
> network. But in tests that I was doing there are moments at which when
> trying to login using ssh I can get it and in others I cannot. In this
> second case, tcpdump showed a similar problem to which commented above.
> 
> I have the impression that continues existing some routing problem
> somewhere. Some idea of what can be the problem?
> 
> Thanks in advance for your reply.
> 
> Regards,
> Daniel



-- 
"We've had no evidence that Saddam Hussein was involved in Sept. 11."

	- George W. Bush
08/17/2003
Washington, DC

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