vpn mac address

Unanswered Question
Nov 19th, 2008


i am connecting to my office over a vpn with the cisco vpn client ver

all works fine for the vpn. where i am having my issue is on the mac address side. it seems that the vpn client, no matter what my ip is, always gives the same mac address to all clients.

so anyone that i have connect to the office over the vpn, even if they have their own static assigned ip the mac address is the exact same as mine or anyone else that connects.

where this is causing a problem is i am running an ip softphone software and it is checking it by the mac address. so basically if i connect after someone else it gives me their extension instead of my own.

i realize i have to take some of this up with the software company but i wanted to know if there was a way to make each connections mac address unique?


I have this problem too.
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John Blakley Wed, 11/26/2008 - 12:07

"it seems that the vpn client, no matter what my ip is, always gives the same mac address to all clients."

I don't understand the above statement. Are you using this client on a proxy server or something, and the clients gateway is set to the proxy server?

When you use the software on any host, you get a mac address assigned to your host? The way it should work is you connect to your device and it gets the address from the local pool. The vpn client installs a virtual adapter in Windows, and this adapter would hold the mac address. You may be able to change that mac address if, for some reason, they've all turned out to be the same. What are you connecting to on the other end?


jefforamma Fri, 11/28/2008 - 10:01

basically if i connect with the cisco vpn client on my laptop and do an ipconfig /all it shows the cisco systems vpn adapter info with a mac address of say 00-12-3a-4b-56-78.

if i then connect from my home pc with same client and do the ipconfig /all it shows the exact same mac addess as my laptop for the cisco vpn adapter.

it does this for anyone that uses the vpn software.

the only reason im running into problems is when the software connects it defaults to the cisco vpn as the nic to use for traffic for the voip app. on my pbx side it looks at the mac for the registration info.

so i can connect, get my extension and work fine. but if i log off, and bob connects and has the same mac address, it will now use my extension on his voip phone instead of his own.

i have a workaround in the app right now. it seems to work fine if i pick the local nic or wireless nic instead of the vpn one. that way they are unique but in some cases it still seems to auto pick that cisco vpn one for some reason.

would just be nice it there was a way to make each vpn mac unique.


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