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Ports are used when any program accesses the Internet so that the system can keep separate applications' data separate. Some port numbers are reserved for functions such as e-mail or FTP. To prevent potential security risks if a protocol was allowed access a port reserved for a seperate protocol, Gecko applications contain a list of banned ports. This preference allows you to unban a port banned by default and therefore prevent the "Access to the port number given has been disabled for security reasons." or "This address uses a network port which is normally used for purposes other than Web browsing. Firefox has canceled the request for your protection." messages.

Possible values and their effects

A comma delimited list of port numbers to allow.


  • This preference does not exist by default.
  • Unblocking ports may pose a security risk.

First checked in

2005-06-19 by Doug Turner

Has an effect in

  • Netscape (all versions since 6.1)
  • Mozilla Suite (all versions since 0.9.1)
  • Phoenix (all versions)
  • Firebird (all versions)
  • Firefox (all versions)
  • SeaMonkey (all versions)

Related bugs

Related preferences

External links