/var/run/squid should be created

[Mosibi]

When running Squid in SMP mode, the IPC sockets are created in /var/run/squid. When that directory is missing, or does not have the right permissions, Squid is not going to listen on the configured http_port and shows the following message in the cache.log: commBind Cannot bind socket FD 20

[ra-at-diladele-com]

Sorry and how do I switch Squid to SMP mode to test this?

[Mosibi]

Sorry and how do I switch Squid to SMP mode to test this?

That's very simple, just put `workers 2' in squid.conf. See also http://www.squid-cache.org/Versions/v4/cfgman/workers.html . I have 4 workers configured, 1 for every CPU in that system

[thctlo]

A simple fix.
/usr/lib/tmpfiles.d/squid.conf
d /run/squid 0755 proxy proxy -

And /var/run is linked to /run

Thank you Raphael for the Ubuntu packages.