Connected to VPN, able to ping but no internet access

[Xensoul]

I am not able to access the internet with my VPN connected and i am able to ping the server.
I am using a vps server for my openvpn server.
My Laptop is on ubuntu. I can't access the internet from my campus but i am connected successfully.

Hopefully someone can help me. Thanks.

[janjust]

make sure you're using

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push "redirect-gateway def1"

on the VPN server; also make sure that ip forwarding is enabled and that masquerading is turned on:

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echo 1 > /proc/sys/net/ip4/ip_forward
modprobe iptable_nat
iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE

[Xensoul]

make sure you're using

Code: Select all

push "redirect-gateway def1"

on the VPN server; also make sure that ip forwarding is enabled and that masquerading is turned on:

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echo 1 > /proc/sys/net/ip4/ip_forward
modprobe iptable_nat
iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE

Thanks for the reply.

I am using push "redirect-gateway def1"

however when i try

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echo 1 > /proc/sys/net/ip4/ip_forward
modprobe iptable_nat

I get FATAL: Could not load /lib/modules/2.6.32/modules.dep: No such file or directory for both.

Edit: I have ask my hosting they say that current there are no MASQUERADE service on their vps. They ask me to try to work around using SNAT and DNAT.

[Xensoul]

It's working at my home now. Gonna test when i am in campus.

[krzee]

sounds like they are using openvz...
try

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iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to <PUBLIC-IP>

you still need ip forwarding, the command JJK gave you should still work fine:

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

for a temp solution (til reboot) or

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echo "net.ipv4.ip_forward = 1" >> sysctl.conf

for perm solution

[Xensoul]

sounds like they are using openvz...
try

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iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to <PUBLIC-IP>

you still need ip forwarding, the command JJK gave you should still work fine:

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

for a temp solution (til reboot) or

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echo "net.ipv4.ip_forward = 1" >> sysctl.conf

for perm solution

Hmm.. it's working at my home but not in my campus. I have known that my compus have port 80, 443 and 22 open. So i am using 22.

Edit: i realise that it works after i start the vpn for awhile. Like 20 seconds? Then can't access after that.
Side note: You can only connect to the ISA or school vpn to access internet in my school.

[janjust]

if the VPN works for 20 seconds and then stops then I'd suspect a smart campus firewall (you're on The Great LAN, I presume) - there's little you can do about that. OpenVPN does not "hide" itself from firewalls , so a modern firewall with deep packet inspection can easily see that it's openVPN traffic that is flowing over the SSH port instead of SSH traffic.

On the other hand, if you have SSH access then why not simply use that? Set up SSH on your home server, 'ssh' to it using port forwarding, e.g.

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ssh -D 1080 <user>@<IP>

and then use either SOCKS support in your client apps or use 'socks-proxy' to run a VPN tunnel over the SSH tunnel .

[Xensoul]

Yup i have been using the SSH access for the socks-proxy. But it does not allow me to update my ubuntu or install application from the software centre as it seems it was blocked. I wasn't able to torrent too.

I have a friend who is able to use his OpenVPN in the campus. I asked him how he do it. He told me he just follow the guide in ubuntu wiki. Well i did follow the guide too. Just not sure why i can't and he can.

[janjust]

what I meant by 'socks-proxy' was that you can
* set up the SSH tunnel using '-D 1080' to your remote host
* also set up OpenVPN on the remote host
* configure OpenVPN to use a socks proxy

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socks-proxy 127.0.0.1

this will establish a VPN tunnel via the socks proxy - you should be able to torrent anything over that.

[Xensoul]

what I meant by 'socks-proxy' was that you can
* set up the SSH tunnel using '-D 1080' to your remote host
* also set up OpenVPN on the remote host
* configure OpenVPN to use a socks proxy

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socks-proxy 127.0.0.1

this will establish a VPN tunnel via the socks proxy - you should be able to torrent anything over that.

Opps. I am sorry. Misunderstood what you mean. I will give it a try when i go back to school tomorrow. Thanks

[Xensoul]

I got it working by changing my machine to connect to dns 8.8.8.8
Learn it from someone i know.

Thanks to all who help.

Cheers.