Warning: Any example presented here is provided "as-is" with no support or guarantee of suitability. If you have any further questions about these examples please email the squid-users mailing list.
Viber Messenger is end-to-end encryption messenger/VoIP/group chats/file transfers application. Using it may be prohibited by corporate security policy.
Usually Viber works in most Squid's setups without any additional configuration. Blocking it, however, require some additional steps. To block Viber, you require SSL Bump-aware squid, or, at least, peek-n-splice configuration.
Squid Configuration File
Paste the configuration file like this:
# Block Viber acl deny_viber ssl::server_name_regex .viber\.com acl DiscoverSNIHost at_step SslBump1 ssl_bump peek DiscoverSNIHost ssl_bump terminate deny_viber ssl_bump splice all
then reconfigure Squid.
This is enough to make Viber fully unoperable (both desktop/mobile).