Hi,
Yesterday I installed Fedora 25. After installing I installed Squid-4.0.17 (default). My external ip is w.x.y.z/28 on enp4s0 and and internal ip is a.b.c.d/22 on enp2s0. The firewalld is configured as below:

internal (active)
target: default
icmp-block-inversion: no
interfaces: enp2s0
sources: a.b.0.0/22
services: ssh mdns samba-client dhcpv6-client squid samba ftp http https pop3 pop3s smtp smtps
ports:
protocols:
masquerade: no
forward-ports: port=80roto=tcp:toport=3128:toaddr=a.b.c.d
source-ports:
icmp-blocks:
rich rules:

external (active)
target: default
icmp-block-inversion: no
interfaces: enp4s0
sources:
services: ssh
ports:
protocols:
masquerade: yes
forward-ports:
source-ports:
icmp-blocks:
rich rules:

Now when starting squid with http_port 3128 sans intercept it starts and works fine. But intercept is added and restart / start it fails to start.

Can someone help me, please. If I failed to provide any further information for clarity, please ask.

I don't really know what you are asking. See this page: https://www.linux.com/learn/weekend-...hing-web-proxy

I am sorry AwesomeMachine. Thanks for your reply.

In my case Squid 4 version is installed in Fedora 25. After configuring firewalld and squid, it works well without intercept mode, i.e. with But in intercept mode squid fails to start, i.e. with

Squid occasionally needs to generate URLs for clients to fetch supplementary content. Images in error pages or FTP and Gopher indexes, cache digests, NetDB, cache manager API, etc.

In order to produce a valid URL Squid requires a port configured to receive normal forward-proxy traffic. The standard well-known port assigned for this is port 3128.

This error occurs when port 3128 has been incorrectly altered into a interception port.

So I left and added another line Voila! The squid started and is working. Thanks to all you guys there.