Client doesn't send arp response after OpenVPN is connected

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SecureOrNotSecure
OpenVpn Newbie
Posts: 3
Joined: Mon May 09, 2016 11:38 pm

Client doesn't send arp response after OpenVPN is connected

Post by SecureOrNotSecure » Sun Aug 13, 2017 11:30 am

Hi All,

My OPenVPN Client (Ubuntu 14.04) connects sucessfully to OpenVPN server (TUN mode).

Situation:
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Tunnel works.
After a few seconds, the tunnel doesn't transport data any more.

Analysis:
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In TCP dump I see, that after the VPN is established, the Client stopps to answer ARP requests at all i.e. on all interfaces.
After three ARP requests from the client's router/gateway (asking for Ubuntu client's MAC), the router/gateway stopps forwarding packets to Ubuntu client. That's why the tunnel stopps working after a few seconds.

If I stopp OpenVPN client, the client starts answering ARP requests immediately

I was able to reproduce this issue on two different machines (same VPN client config).

Versions:
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OpenVPN client: 2.4.3 (Jun 20 2017)
Ubuntu: 14.04.5 LTS (4.4.0-38-generic)


Can you please help me to keep to tunnel alive i.e. keep the client answering arp requests?

Thank you in advance!

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TinCanTech
OpenVPN Protagonist
Posts: 2961
Joined: Fri Jun 03, 2016 1:17 pm

Re: Client doesn't send arp response after OpenVPN is connected

Post by TinCanTech » Sun Aug 13, 2017 7:39 pm


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