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I'm trying to setup my own little access point and I've got two core elements of it working.

  1. The WiFi Access point is connectible. I can access a webserver on the router
  2. SSH-ing into the router, I can connect to the outside internet via PPTP

Does anyone know of any way I can connect the two elements together?

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1 Answer 1

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First you need to enable IP forwarding:

echo 1 > /proc/sys/net/ipv4/ip_forward

Then presuming that your VPN assigns a static IP you'll need SNAT:

iptables -t nat -A POSTROUTING -o <TUNNEL INTERFACE> -j SNAT --to-source <VPN IP>

replacing and as appropriate ofc. If your VPN gives you a dynamic IP, you'll need to use MASQUERADE instead:


Then check that your routing table is correct with:

route -n

check that you have a line similar to this:         <VPN ENDPOINT IP>         UG    2      0        0 <VPN INTERFACE>

if it's missing, add it:

route add default gw <VPN ENDPOINT IP> dev <VPN INTERFACE>

Each distro has it's own methods of making these changes permenant/persistant, so I'd need more info to help in that regards.

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I am using a debian on a raspberry Pi. I'm able to send packets as running tcpdump on ppp0 shows: 12:03:48.687991 IP rras-10-34-9-1.ncl.ac.uk.38988 > google-public-dns-b.google.com.domain: 10290+ A? accounts.google.com. (37) –  Joe Simpson Oct 3 '13 at 12:05
Oh wait, I can access Google via ip address over the network now, but dns isn't working at all –  Joe Simpson Oct 3 '13 at 12:26
You'll need to be more specific, DNS isn't working from where? What's the content of the pi's /etc/resolv.conf? the clients's /etc/resolv.conf? what's the pi's routing table? is /proc/sys/net/ipv4/ip_forward set to 1, etc etc –  Nanzikambe Oct 3 '13 at 15:45
Yeah. I can access Google direct via ip address and dns works fine from the pi itself. Dns simply isn't working from a computer on the network –  Joe Simpson Oct 3 '13 at 15:46
After doing a random test on changing DNS servers, it seemed by Uni VPN blocked any DNS that wasn't going to their DNS servers. Thanks anyway :) –  Joe Simpson Oct 4 '13 at 19:32

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