How to use Synergy between local LAN and VPN connected PCs

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How to use Synergy between local LAN and VPN connected PCs

Postby Jean-Pierre Masse » Sun Oct 02, 2016 6:13 am

I'm trying to see if there is a way to make my Synergy server laptop (MAC Book Pro), on my Home network, connect to my company PC also on the same network except, the Cisco client VPN is connected to my Company.

It seem my company do not permit to enable 2 network connection, VPN use the wireless one but disable the physical connection, so I can't enable it.

Can we use the Synergy with Bluetooth, USB or other way?

What will be the performance if I try to do it through the internet?

Thanks in advance for your support.
Jean-Pierre Masse
QC

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Re: How to use Synergy between local LAN and VPN connected

Postby Tapio Luukkanen » Wed Oct 05, 2016 3:46 am

I'm successfully using a similar setup with an Ubuntu Synergy server and Windows 8 Synergy client.

The Windows client workstation is connected to 1-3 different VPN networks for my work.

You need to ensure that your VPN client software can be configured to allow local LAN access so that it can reach to your MAC.

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Re: How to use Synergy between local LAN and VPN connected

Postby Micro » Fri Oct 07, 2016 6:33 am

I'm using a Mac as my server. Pc as my extended setup. My mac is connecting to a L2TP VPN and funnelling all traffic. I am still able to use synergy to a Windows 10 PC connected to the same local network not on the VPN.

I am using the hard coded server IP on my windows machine pointing to my Mac server. If that helps.

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Re: How to use Synergy between local LAN and VPN connected

Postby Jonathan Sparks » Tue Nov 22, 2016 11:37 pm

It takes a little work, but it is possible to use Synergy over VPN without split-tunneling. Here is what I did.

1) Register yourself a free (or paid if you don't want 30-day nags) dynamic DNS address (DDNS) from a place like dynDNS or no-ip
2) Register for the Pro version of Synergy to get that sweet, sweet SSL security. You're going to be opening some pin holes, so best to keep the connection secure while in transit
3) Select a non-default port for Synergy to use - again security precaution

From you home network router:
4) Create a DHCP reservation or assign a static IP for your server system
5) Create a port forwarding rule on the router that will forward all traffic destined for the port you determined in step 3 to the IP to determined in step 4 (source should be any IP, any port)

From Server system
6) Install Synergy if you haven't already done so, select server, and register your Pro key from step 2
7) On the Settings menu, enter the port number to determined in step 3, check the "Use SSL Security" box and click OK
8) Click Configure Server and then add your client screens as you normally would

From home router or server system
9a) If router supports automatic dynamic DNS updates, configure your router to update the address you registered in step 1 so your home external IP is tied to your DDNS address
-or-
9b) Install the DNS update client from the service used in step 1 so your home external IP is tied to your DDNS address

From your client system(s)
10) Install Synergy and select Client
11) For "Server IP," enter the DDNS address you created in step 1 (don't use auto config)
12) Make sure to set the same port number from step 3 in the Settings screen
13) Watch the magic happen

I think that about covers it...
Last edited by Jonathan Sparks on Tue Nov 29, 2016 9:27 am, edited 1 time in total.

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Re: How to use Synergy between local LAN and VPN connected

Postby Ryan » Mon Nov 28, 2016 8:32 pm

^^^ that's pretty smart. VPN's that don't allow split tunnels are just downright stupid. :)

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Joined: Tue Nov 22, 2016 11:15 pm

Re: How to use Synergy between local LAN and VPN connected

Postby Jonathan Sparks » Tue Nov 29, 2016 9:16 am

Ryan wrote:^^^ that's pretty smart. VPN's that don't allow split tunnels are just downright stupid. :)


You actually want split tunneling disabled. When it is enabled, you are creating a link between an unsecured external network and an secured internal network. That is a man-in-the-middle attack waiting to happen. By disabling, you force all traffic through secured and monitored appliances.

Yeah, it sucks for people who work from home a lot (like myself), but I think the increased security is worth the hassle...plus I get to come up with creative solutions so I can still work. I get around it by have two systems, one on VPN and one not and using Synergy with SSL enabled to administrate them both simultaneously. If I need to move files between them or print something, I use iDrive ( https://www.idrive.com/idrive/deals/pd/dgtlsparks ) because I can define a custom 256-bit AES key (I own my data, not true for Google Drive and Dropbox) and then use their Sync service to move the files. Drop a file in a folder on one system and it appears in a folder on my other system.

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Re: How to use Synergy between local LAN and VPN connected

Postby Tyler Chaves » Thu Jan 12, 2017 1:45 pm

Jonathan Sparks wrote:It takes a little work, but it is possible to use Synergy over VPN without split-tunneling. Here is what I did.

1) Register yourself a free (or paid if you don't want 30-day nags) dynamic DNS address (DDNS) from a place like dynDNS or no-ip
2) Register for the Pro version of Synergy to get that sweet, sweet SSL security. You're going to be opening some pin holes, so best to keep the connection secure while in transit
3) Select a non-default port for Synergy to use - again security precaution

From you home network router:
4) Create a DHCP reservation or assign a static IP for your server system
5) Create a port forwarding rule on the router that will forward all traffic destined for the port you determined in step 3 to the IP to determined in step 4 (source should be any IP, any port)

From Server system
6) Install Synergy if you haven't already done so, select server, and register your Pro key from step 2
7) On the Settings menu, enter the port number to determined in step 3, check the "Use SSL Security" box and click OK
8) Click Configure Server and then add your client screens as you normally would

From home router or server system
9a) If router supports automatic dynamic DNS updates, configure your router to update the address you registered in step 1 so your home external IP is tied to your DDNS address
-or-
9b) Install the DNS update client from the service used in step 1 so your home external IP is tied to your DDNS address

From your client system(s)
10) Install Synergy and select Client
11) For "Server IP," enter the DDNS address you created in step 1 (don't use auto config)
12) Make sure to set the same port number from step 3 in the Settings screen
13) Watch the magic happen

I think that about covers it...


I am attempting the process on a system with Cisco AnyConnect VPN. Followed your steps but having issues with the client not wanting to connect. Using the hostname to connect, getting error:
WARNING: failed to connect to server: Timed out.

No message comes up on the server, however. I can check the port I forwarded using portchecktool.com on my external IP, and it detects the service is open. Not sure what could be causing it. The hostname is properly registered using the tool offered from no-ip to my external IP address.

EDIT: Just to check, issue does occur with the VPN both enabled or disabled. With the VPN disabled, I can connect to the server with the local IP address.

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Joined: Tue Nov 22, 2016 11:15 pm

Re: How to use Synergy between local LAN and VPN connected

Postby Jonathan Sparks » Thu Jan 12, 2017 3:06 pm

Tyler Chaves wrote:
I am attempting the process on a system with Cisco AnyConnect VPN. Followed your steps but having issues with the client not wanting to connect. Using the hostname to connect, getting error:
WARNING: failed to connect to server: Timed out.

No message comes up on the server, however. I can check the port I forwarded using portchecktool.com on my external IP, and it detects the service is open. Not sure what could be causing it. The hostname is properly registered using the tool offered from no-ip to my external IP address.

EDIT: Just to check, issue does occur with the VPN both enabled or disabled. With the VPN disabled, I can connect to the server with the local IP address.


Okay, this sounds like a DNS resolution issue to me - let's try a couple tests.

With VPN disabled, from your client machine (assuming ICMP is enabled for the external interface of the router):

Is nslookup or dig resolving the dynamic DNS name correctly (is it returning your external IP)?
Are you able to ping your server via the dynamic DNS name?
Are you able to telnet to the server port via the dynamic DNS name?
Will Synergy connect if you use the external IP for your server?
Is the port forwarding counter increasing on your router when you are attempting the connections?

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Joined: Thu Jan 12, 2017 1:41 pm

Re: How to use Synergy between local LAN and VPN connected

Postby Tyler Chaves » Thu Jan 12, 2017 3:45 pm

Jonathan Sparks wrote:Okay, this sounds like a DNS resolution issue to me - let's try a couple tests.

With VPN disabled, from your client machine (assuming ICMP is enabled for the external interface of the router):

Is nslookup or dig resolving the dynamic DNS name correctly (is it returning your external IP)?
Are you able to ping your server via the dynamic DNS name?
Are you able to telnet to the server port via the dynamic DNS name?
Will Synergy connect if you use the external IP for your server?
Is the port forwarding counter increasing on your router when you are attempting the connections?


1. It does resolve correctly showing my external IP
2. Yes, off the VPN only.
3. Yep, ablet to telnet using adminkit.net
4. It does not, the same issue occurs using the IP.
5. Can't seem to locate any sort of counter, I am checking logs but no luck at the moment.

Tested with another system, same exact issue so definitely unrelated to the VPN, but the DNS resolves correctly from what I can see so far. Lost at this point.

EDIT: For now, I have employed a workaround that fulfills my needs at the moment. Thanks for the response to my issue, if you have more ideas for troubleshooting and feel like posting, I may refer back to this later and other members may find it useful. Thanks again :)

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