Chapter 8. Configuring Applications

All security becomes a trade-off. The more secure your machine is, the more inconvenient some things become. Applying extremely strict rules with Lokkit will mean that you need to learn new ways to do some things. The most commonly-used applications which are affected are listed here:

FTP has two modes of operation, one of which is firewall-friendly. Modern FTP clients tend to support the friendly mode (really called passive mode).

Realaudio and RealPlayer default to using UDP which is hard to firewall. For RealPlayer, you can change it to TCP, which passes firewalls, by following the directions at real.com's Knowledge Base. Essentially, you want to change all mentions of "stream type" from "UDP" to "TCP" in the Preferences dialogue box.

When using IRC clients, you will be unable to make DCC connections. There is no way around this.

Networked Quake will also be affected. There are workarounds for this but they are complicated. The author does not play Quake so would appreciate suggestions on this which are simpler than the Linux IP-Masq-HOWTO document.