Freepbx16 firewall custom prot

[Stewart1 (Stewart)]

Indeed, UDP 5061 is quite popular. See survey

Compiled list of SIP bots

In theory, but in the real world admins (for example) set up trunks with from-internal context or test extensions with very weak passwords, or simply make mistakes. Numerous cases of SIP exploits have been documented in this forum. There are many ways to gain additional protection, including avoiding SIP over UDP altogether, filtering by domain name (trivial but unpopular here, for reasons that make no sense to me), using various static or dynamic block lists (complex and IMO not very secure)…