openvpn: iptables não encaminhando

Question

Eu tenho a seguinte topologia:

Estouseguindoasregrasdoiptableslistadasno link

Aqui está a saída de iptables -L -v

Chain INPUT (policy ACCEPT 1236 packets, 145K bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 407 packets, 25288 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 ACCEPT     all  --  any    any     anywhere             anywhere             ctstate RELATED,ESTABLISHED
    0     0 ACCEPT     all  --  eth0   eth1    192.168.0.0/24       anywhere             ctstate NEW
    0     0 ACCEPT     all  --  tun0   eth1    10.8.0.0/24          anywhere             ctstate NEW
    0     0 ACCEPT     all  --  tun0   eth0    10.8.0.0/24          192.168.0.0/24       ctstate NEW

Chain OUTPUT (policy ACCEPT 1691 packets, 230K bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain LOGGING (0 references)
 pkts bytes target     prot opt in     out     source               destination

Esta é a saída do ifconfig :

eth0      Link encap:Ethernet  HWaddr 00:90:e8:45:96:79
          inet addr:192.168.0.10  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::290:e8ff:fe45:9679/64 Scope:Link
          UP BROADCAST RUNNING ALLMULTI MULTICAST  MTU:1500  Metric:1
          RX packets:47251 errors:0 dropped:341 overruns:0 frame:0
          TX packets:35463 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6700218 (6.3 MiB)  TX bytes:6348389 (6.0 MiB)

eth1      Link encap:Ethernet  HWaddr 00:90:e8:45:96:7a
          inet addr:213.179.150.110  Bcast:213.179.150.111  Mask:255.255.255.248
          inet6 addr: fe80::290:e8ff:fe45:967a/64 Scope:Link
          UP BROADCAST RUNNING ALLMULTI MULTICAST  MTU:1500  Metric:1
          RX packets:431735 errors:0 dropped:1629 overruns:0 frame:0
          TX packets:515499 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:55214512 (52.6 MiB)  TX bytes:93401691 (89.0 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:124 errors:0 dropped:0 overruns:0 frame:0
          TX packets:124 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:12872 (12.5 KiB)  TX bytes:12872 (12.5 KiB)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.8.0.1  P-t-P:10.8.0.1  Mask:255.255.255.0
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:105 errors:0 dropped:0 overruns:0 frame:0
          TX packets:239 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:8100 (7.9 KiB)  TX bytes:18522 (18.0 KiB)

route -n

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         213.179.150.105 0.0.0.0         UG    0      0        0 eth1
10.8.0.0        0.0.0.0         255.255.255.0   U     0      0        0 tun0
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
213.179.150.104 0.0.0.0         255.255.255.248 U     0      0        0 eth1

Eu tenho um cliente em execução e o túnel parece estar estabelecido, já que eu posso fazer ping na interface tun do cliente:

PING 10.8.0.2 (10.8.0.2) 56(84) bytes of data.
64 bytes from 10.8.0.2: icmp_req=8 ttl=64 time=704 ms
64 bytes from 10.8.0.2: icmp_req=9 ttl=64 time=824 ms
64 bytes from 10.8.0.2: icmp_req=10 ttl=64 time=704 ms
64 bytes from 10.8.0.2: icmp_req=11 ttl=64 time=723 ms
64 bytes from 10.8.0.2: icmp_req=12 ttl=64 time=725 ms
64 bytes from 10.8.0.2: icmp_req=13 ttl=64 time=665 ms

No entanto, não consigo pingar "10.8.0.2" da eth0, ou seja, 192.168.0.10:

PING 10.8.0.2 (10.8.0.2) from 192.168.0.10 eth0: 56(84) bytes of data.
From 192.168.0.10 icmp_seq=1 Destination Host Unreachable
From 192.168.0.10 icmp_seq=2 Destination Host Unreachable
From 192.168.0.10 icmp_seq=3 Destination Host Unreachable

Meu palpite é que o ping está falhando porque o gateway padrão não está na mesma sub-rede que o eth0. Mas o tráfego da eth0 não deveria ser encaminhado para o tun0? O que estou perdendo aqui?

Eu tentei adicionar uma regra de encaminhamento de eth0 para tun0: Cadeia FORWARD (política ACCEPT 0 pacotes, 0 bytes)

 pkts bytes target     prot opt in     out     source               destination
    0     0            all  --  eth0   tun0    anywhere             anywhere

mas sem sucesso!

Esqueci de mencionar:

sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1

Aqui está minha tabela NAT:

Chain PREROUTING (policy ACCEPT 1 packets, 28 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain INPUT (policy ACCEPT 1 packets, 28 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 MASQUERADE  all  --  any    tun0    anywhere             10.8.0.0/24
    0     0 MASQUERADE  all  --  any    eth1    10.8.0.0/24          anywhere
    0     0 MASQUERADE  all  --  any    tun0    192.168.0.0/24       anywhere