In addition to the article Lucar has mentioned (https://community.sophos.com/kb/en-us/132436) please make sure that you create a block rule for all unnecessary traffic. Psiphon proxy uses random ports to get access to the Internet, also uses UDP 443 so make sure you block QUIC as well in the firewall rule.
In addition to the article Lucar has mentioned (https://community.sophos.com/kb/en-us/132436) please make sure that you create a block rule for all unnecessary traffic. Psiphon proxy uses random ports to get access to the Internet, also uses UDP 443 so make sure you block QUIC as well in the firewall rule.
