VPN clients getting knocked off when new user logs in

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Level 1

23 points

VPN clients getting knocked off when new user logs in

I am running the latester version of Server (2.2 - Mountain Lion)

The VPN is setup and I can log into it just fine. Outside my LAN OR WITHIN my lap, I am having a problems of a logged in client getting knocked off when a new client logs in. If I log into it with another device (iDevice or my MacBook Pro, etc), whatever device I first logged into the VPN with gets knocked off in a few seconds to maybe a minute with the message "You were disconnected because the PPP server is not responding. Try reconnecting."

Happens every single time. I even tried creating separate user accounts for each device, thinking it was logging into the VPN / Server with the same account. But that is not the case. Creating separate accounts creates the same problem, no change.

I did find a reference to the problem in a post a while back and someone in response mentions that this is a limitation of the Server. No way that is possible. If there was no way to have multiple people/devices log into a server from a single IP source somewhere, VPN would be useless and never used. You have to be able to log multiple people into it.

Looking at the logs, I do see moments when the device gets bumped off. It usually includes messages with:

Unsupported Protocol 0x8057 received

rcvd [LCP TermReq id-0x3 "Peer not responding"]

LCP terminated by peer (Peer not responding)

fatal signal 6

no echo reply, start ppp_auxiliary_probe!

No response to 5 echo requests

Serial link appears to be disconnected.

Client with address = 10.0.1.xxx has hung up

Any suggestions as to what is going on or how to fix this?

Thanks.

Posted on Jan 9, 2013 6:53 PM

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Answer 1

Camelot

Level 9

54,333 points

Jan 9, 2013 8:00 PM in response to kb8wfh

Are you saying that you have multiple clients connecting from the same remote IP address?

If that is the case then, yes, you will have problems. Due to the way the traffic is encrypted it's difficult for the server to identify connection A from connection B, so the earlier sessions will disconnect. It does not matter whether they are using the same account or not, it's all based on their IP address.

There are three common solutions - the first is to run multiple VPN protocols. Mac OS X Server supports PPTP and L2TP. You can connect one client on each, even from the same IP address, and not run into problems.

If you have more than two clients from the same IP address then this won't work, of course. A solution here involves either configuring a site-to-site VPN (rather than a client-to-site VPN), so that every device on the remote network shares the same VPN connection.

The last option is to replace your router on the remote (client) end with one that supports multiple VPN tunnels via NAT-T - this extension allows multiple clients to maintain a VPN connection, but not all routers support it.

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