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No internet connectivity for local bridge with TAP adapter

Posted: Sun Jul 20, 2014 12:42 pm
by myopenid
I currently have a VPS at DigitalOcean and attempted to create a local bridge between a tap adapter with the virtual hub. I've enabled the necessary configurations, such as the iptables NAT and kernel ip forwarding, but no internet. When I check to see what is going on in the tap adapter with wireshark, it seems that packets from the virtual hub never reached the tap adapter, hence no forwarding or any internet connectivity. It's as if the virtual hub has swallowed the packets.

So what is the problem???

/////////my ifconfig/////////////

eth0 Link encap:Ethernet HWaddr 04:01:20:6a:fa:01
inet addr:XXX.XXX.XXX.XXX Bcast:128.199.255.255 Mask:255.255.192.0
inet6 addr: fe80::601:20ff:fe6a:fa01/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:638079 errors:0 dropped:0 overruns:0 frame:0
TX packets:923180 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:561702355 (561.7 MB) TX bytes:707333046 (707.3 MB)

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:65536 Metric:1
RX packets:8012 errors:0 dropped:0 overruns:0 frame:0
TX packets:8012 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2637417 (2.6 MB) TX bytes:2637417 (2.6 MB)

tap_soft Link encap:Ethernet HWaddr 00:ac:af:83:9e:4f
inet6 addr: fe80::2ac:afff:fe83:9e4f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2062 errors:0 dropped:0 overruns:0 frame:0
TX packets:773 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:243181 (243.1 KB) TX bytes:63990 (63.9 KB)

/////////Softether server version//////
v4.08-9449-rtm-2014.06.08-linux-x86-32bit

There is no NAT or any firewall. The vpncmd test says everything pass. The vpn configs are all defaults.

Re: No internet connectivity for local bridge with TAP adapt

Posted: Mon Jul 21, 2014 12:08 am
by inten
Why are you bridging Eth0? What for?

Re: No internet connectivity for local bridge with TAP adapt

Posted: Mon Jul 21, 2014 5:05 pm
by myopenid
inten wrote:
> Why are you bridging Eth0? What for?

I'm bridging the tap adapter not the eth0.

Re: No internet connectivity for local bridge with TAP adapt

Posted: Mon Jul 21, 2014 7:55 pm
by inten
Attach your SE VPN server config.

Re: No internet connectivity for local bridge with TAP adapt

Posted: Tue Jul 22, 2014 11:33 am
by myopenid
inten wrote:
> Attach your SE VPN server config.
Attached is my server config.

Re: No internet connectivity for local bridge with TAP adapt

Posted: Tue Jul 22, 2014 2:34 pm
by inten
show the output of "iptables -L -t nat".
What DHCP server do you use?

Re: No internet connectivity for local bridge with TAP adapt

Posted: Wed Sep 10, 2014 7:13 pm
by myopenid
My NAT config is this:
iptables -t nat -A POSTROUTING -s 192.168.30.0/24 -j SNAT --to-source x.x.x.x
This has no problem.

I already solved this long time ago, sorry for replying late.

Basically the problem was that I was using the built in softether DHCP server + iptables for the network. Apparently this will cause it to eat packets and packets will never reach the tap adapter.

Use dnsmasq instead.