Get Important Information About Internet Elements

What is a proxy?

A proxy is an application level gateway, typically placed between two networks. Proxies have various uses, including use in a firewall to further isolate two networks. Proxy software is often marketed as a way to share a single internet connection between computers.


What is Network Address Translation (NAT)? (including cable/DSL modem and router)

Quite simply, network address translation is a way to rewrite the addresses of packets as they travel through a system. Typical uses include allowing several computers to share a single internet connection. NAT can also reinforce the security provided by a firewall, and in some cases provide equivalent levels of security. Typical devices that perform NAT functions for the average computer user may be routers, cable/DSL modems or hardware firewalls that allow multiple computers to connect to it, or computers dedicated to the task of "masquerading" or "internet connection sharing" (ICS). If you are a cable/DSL modem/router user and you're having problems, first look through questions 1-17 to understand the terminology, then see #18 at the bottom to find specific help for many router setups.

What is DCC


 DCC stands for DIRECT CLIENT TO CLIENT (see technical specification). DCC is a crude hack used to allow two IRC clients to communicate directly without involving the IRC server. Typical uses include accessing IRC robots (or 'bots) for short, extended private conversations between two users, and file transfers.


What is identd?

 identd is a server for the "Identification Protocol" defined by RFC 1413 [ext. link]. Essentially, it provides for the accountability of individual users beyond the local system. It was originally created at a time when most systems on the internet were large, multi-user systems. It is still used today, mostly by IRC, SMTP, and FTP servers.

Why do IRC servers require identd?

Even though identd is intended for multiuser systems, IRC servers typically require it to be installed, even for single user systems. One reason for this is that it increases the technical difficulty of "spoofing" attacks (see next question). Another is that operators of unsecured proxies typically don't provide for identd. By requiring identd, the servers reject potentially abusive connections from those proxies.