轉貼
http://www.mozilla.org/releases/mozilla1.5/known-issues.html上的文字(在Security這一段)
For security reasons, Mozilla does not allow connections to certain ports. To override this on a per-port basis, add a comma separated list of ports to defaults/all.js (in your Mozilla installation directory). Note that this pref only works in the all.js file in the Mozilla installation directory and it affects all users of the installation. It does not work if you add it to the prefs.js or user.js files in your personal profile directory. For example, to unblock ports 1, 3, and 7, use the following line: pref("network.security.ports.banned.override", "1,3,7");
簡單的說,為了安全性的理由,Mozilla不允許連接到某些ports,這可以藉由修改all.js這個設定檔來解除這個限制,例如要開放port87的話:
pref("network.security.ports.banned.override", "87");