Description
This tag name is used to specify the socket addresses where Squid will listen for HTTP client requests. Multiple socket addresses can be specified. There are three forms: port alone, hostname with port, and IP address with port. If hostname or IP address is specified, then Squid binds the socket to that specific address. This replaces the old "tcp_incoming_address" option. Most likely, there is no need to bind to a specific address, so the port number alone can be used. If Squid is to be run in accelerator mode, then it should listen on port 80 also, or instead.

Example
Give the port number in which you want squid to listen to http client requests. Like...
http_port 8080
We can override the default port number by '-a ' command line option.
#/usr/local/squid/bin/squid -a 8080
This will start squid with port 8080, which overrides the port number in squid.conf. However this option cannot be used to override IP address

Caution
Before changing the port number, make sure no application in your box is running in the same port.

Note
http_port can be used to specify the tcp_incoming_address through which the cache listens to requests from other remote servers. http_port can be listed multiple times.

Description
This specifies the port number from which Squid sends and receives ICP queries to and from neighbor caches. To disable "0" is used.

ICP is a protocol used for communication among squid caches. ICP is primarily used within a cache hierarchy to locate specific objects in sibling caches. If a squid cache does not have a requested document, it sends an ICP query to its siblings, and the siblings respond with ICP replies indicating a ``HIT'' or a ``MISS.'' The cache then uses the replies to choose from which cache to resolve its own MISS. ICP is currently implemented on top of UDP. Squid also supports ICP via multicast.

Example
The port number is given in which squid has to send and receive ICP queries from neighbor caches. Like...

icp_port 5050
May be overridden by -u command line option.

#/usr/local/squid/bin/squid -u 5050
This will start squid with port 5050, which overrides the port number in squid.conf

Caution
Before changing this port number, make sure no application in the box is running in the same port.

Description
Used to specify the port number through which Squid sends and receives HTCP queries to and from neighbor caches. To disable "0" is used.

Example
htcp_port 5089

Caution
To enable this option, you must use --enable-htcp with the configure script.

Description
This tag specifies a list of multicast groups, with which your server should join to receive multicasted ICP queries.

Multicast is essentially the ability to send one IP packet to multiple receivers. Multicast is often used for audio and video conferencing systems. If you are unsure about multicast, please read the Multicast chapter in the Squid FAQ (http://squid.nlanr.net/Squid/FAQ/).

This option is to be set only if you want to RECEIVE multicast queries.

ICP replies are always sent via unicast, so this option does not affect whether or not you will receive replies from multicast group members.

Be sure you understand the difference between an ICP _query_ and an ICP _reply_.

Use cache_peer Directive for sending ICP queries.

Example
mcast_groups 239.128.16.128 224.0.1.20

Caution
Should not use a multicast address, which is already in use by another group of caches. We should not set this option to SEND multicast ICP.

Description
It is used for connections made to remote servers. It is also used to communicate with other caches while using HTCP or CARP. Normally tcp_outgoing_address should not be specified. It is better to let the OS select a suitable address. There are some very specific network configurations where tcp_outgoing_address needs to be specified

Example
The tcp_incoming_address can be specified using http_port.

Description
It is used for the ICP socket receiving packets from other caches.

Caution
Cannot have the same value, since they both (udp_incoming_address and udp_outgoing_address) use the port 3130.

Description
It is used for the ICP packets sent out to the caches.

Caution
Cannot have the same value, since they both (udp_incoming_address and udp_outgoing_address) use the port 3130.