Fixing Firefox/Iceweasel restricted port

Today I ran into this warning from iceweasel when I tried to access a web service on port 101:

This address is restricted

This address uses a network port which is normally used for purposes other than Web browsing. Iceweasel has canceled the request for your protection.

I found this article which said:

  • Open about:config
  • Create if it’s not there
  • Set that setting as, e.g.: 101-104
  • Refresh the page