Does a Squid Parent Proxy Need an ICP Port?

Your upstream service supplies one HTTP proxy port. Squid's cache_peer syntax asks for two. The extra field is for cache queries, not a second mandatory forwarding connection.

cache_peer parent.example parent 8080 0 no-query name=office_parent

Here 8080 carries HTTP proxy requests. The zero occupies the query-port field; no-query disables ICP queries to this peer. The parent need not implement ICP.

It does need to speak HTTP proxy protocol. If the parent will be public, the HTTP proxy list provides HTTP candidates to check. A SOCKS port will not work in its place. For HTTPS, check that the parent permits the required CONNECT destination; ICP support is unrelated.

Keep access control and onward-routing policy separate. Declaring this peer neither authorizes clients nor forbids direct fallback. Retain the appropriate http_access, peer-selection, and never_direct rules for the intended requests.

An ICP-port change cannot repair a rejected proxy login or a denied CONNECT destination.