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Old 01-19-2017, 05:22 PM   #1
snovosel112811
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Registered: Jan 2017
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Should tun0 ip address match on both client and server (openvpn)


Hello everyone, simple question here:

When I run ifconfig on my client I receive the following (when connected to the VPN)


Code:
[ tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:10.8.0.6  P-t-P:10.8.0.5  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:108 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:0 (0.0 B)  TX bytes:7540 (7.5 KB) ]
When I run the same command on my server:

Code:
[ 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:10.8.0.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:172 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:10560 (10.5 KB)  TX bytes:264 (264.0 B) ]
Should the inet addr match for both server and client? When I connect to my VPN server, I can connect but can't connect to the internet. I also can't ping anything.

Last edited by snovosel112811; 01-19-2017 at 05:24 PM.
 
Old 01-19-2017, 09:10 PM   #2
sundialsvcs
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Actually . . . "No! ... Absolutely not!"

"The various participants in your OpenVPN network," including both the servers and any-and-all clients who are connected directly to them, necessarily must have a private-to-them range of IP-addresses through which they can communicate among themselves, without any conflict against any (client ...) address-range whose communications they might be passing from here to there.

Typically, this agreed-upon address range is (say ...) 10.8.0.x.

The OpenVPN server carves-out a couple of these addresses for itself, then doles-out other ones both for "other servers" and for directly-connected machines who are running OpenVPN-client software directly.

"The 10.8.0.x subnet," therefore, is "a subnet that OpenVPN reserves unto itself," trusting that no other 'private subnet' anywhere on Planet Earth would dare(!) to conflict with its sovereign addresses. OpenVPN expects to be able to use these addresses to communicate directly among the various other OpenVPN clients/servers in its present network, as well as the various clients who are directly connected to any of them.

(If your machine happens to host more-than-one OpenVPN process, then ".8" might turn out to be a sequentially-larger number ... but, I digress.™)

- - -
"And of course, this is merely the usual TCP/IP Routing™ use-case . . ."

Last edited by sundialsvcs; 01-19-2017 at 11:07 PM.
 
  


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