Firewall/NAT

Hello i have a few monowalls on my place different versions each

1.3b7 - 1.33 - 1.31 .... and i need to be able to block teamviewer how can i get that done?

Have you tried blocking destination TCP port 5938?

Yes i have with no luck, i can't block port 80 because i have some websites was well

Please be more specific when you say you want to block Teamviewer.

Do you wish to prevent users behind your m0n0walls from using TeamViewer to reach other remote desktops?

Or do you wish to prevent others out on the internet from connecting to Teamviewer running on user machines behind your m0n0walls?

i have a user on this operation that i think is using company information in he's own good $$$$ now we do have teamviewer on user machine 4 technician proposes i already have changed passwords once but the information still going out.
so
i wish to prevent others out on the internet from connecting to Teamviewer running on user machines behind my m0n0walls

so i want them to be able to use teamviewer when their here LAN but not when they are in some other places, unknown places

Sorry, but I am lost. I just don't understand exactly what it is you wish to prevent.

i wish to prevent others out on the internet from connecting to Teamviewer running on user machines behind my m0n0walls

Probably u r try meddling on "DNS resolver" side.

The way team viewer works, this is not possible.  Even if you are "on the same lan" you are still connecting through the teamviewer server.  So it either works, or does not.

Consider some form of logging instead.