Cisco AnyConnect VPN interference?

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Joined: Wed Feb 17, 2016 10:23 am

Cisco AnyConnect VPN interference?

Postby Christopher Nagel » Wed Feb 17, 2016 10:45 am

I am connecting 2 semi-equivalent MacBook Pro's using Synergy 1.7.5 (precompiled) on Mac OS X 10.11.3.

The synergy client computer also requires a VPN connection to an external organization via Cisco AnyConnect, and I notice that Synergy is suddenly unable to find the client when I start the VPN. I have bypass proxy settings on for *.local, but I suspect the 10.0.1/8 subnet may be part of the VPN's routing table although I haven't determined how to verify this.

I did ping between server and client I got:
Code: Select all
--- ping statistics ---
6 packets transmitted, 6 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 23.319/61.568/106.769/27.152 ms

Client to server:
Code: Select all
ping: sendto: Host is down
Request timeout for icmp_seq 11
--- ping statistics ---
13 packets transmitted, 0 packets received, 100.0% packet loss

Then I ditched the VPN, waited a minute and Synergy (and ping) works fine (hence being able to paste in the ping stats from client here)!

Has anyone experienced cut-out of Synergy due to Cisco Anyconnect *or other VPN software? What's a typical solid solution? Should I change the IP range of my internal network or is there a better solution? I'm updating my WiFi router to deal with the awful performance, so it's a perfect time to modify the internal addresses.


Posts: 4
Joined: Wed Feb 17, 2016 10:23 am

Re: Cisco AnyConnect VPN interference?

Postby Christopher Nagel » Thu Feb 18, 2016 9:07 am

I've gotten a little more information since my post.

Cisco VPN's can be set up to either split tunnel (only apply to certain addresses or ranges) or take over the entire network interface. This is determined at the remote end, not on the client. Some companies feel it's more secure to disallow any local or internet access while on the VPN.

A workaround to this is demonstrated here, but on Mac OS X, it will require me to learn kernel extension development, since netlink.h is not part of the OS X distro.

It strikes me to ask if Synergy can be modified to work over Bluetooth? My 2 laptops are 3 feet apart and Bluetooth is not screwed by the VPN.

Is there any hope for such an option or is it way too much traffic for BT?

Posts: 7
Joined: Tue Nov 22, 2016 11:15 pm

Re: Cisco AnyConnect VPN interference?

Postby Jonathan Sparks » Tue Nov 22, 2016 11:41 pm

This can be accomplished without using split tunneling, I posted my fix over here:


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