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5.1 Acronyms and technical terms

This section contains definitions of some of the acronyms and technical concepts used in this manual. This probably won't suffice to get you up to speed if you are completely unfamiliar with IRC and networking, but hopefully it will help.


"Chargen", or the character generator, is a TCP/IP service commonly available on Unix systems. It is generally located on port 19, and does nothing but recite the alphabet for you, repeatedly, as fast as it can.

Very stimulating!


"Cracker" is the preferred term for a person who breaks into or otherwise violates computer system security without permission. Calling such people "hackers" really gets on real hackers nerves.

Read the Jargon file's definition.


CTCP, or Client To Client Protocol, defines a few special types of messages which the clients use to initiate DCC transmissions, trigger sounds or implement actions.


DCC, or Direct Client Connection, is a protocol used by IRC clients to send messages (DCC CHAT) or files (DCC SEND) directly, bypassing the IRC network.

See the subsection about the DCC protocol for information about how DCC CHAT and DCC SEND are implemented.


DCC RESEND and TRESEND are enhancements to normal DCC SEND.

Before data transmission begins, the clients exchange information about at what file offset to begin, allowing the user to resume an uncompleted transmission.


DCC RESUME is an non-standard extension to DCC, introduced by the mIRC client to allow people to resume a previous, uncompleted file transmission.

This solution is inferior to the DCC RESEND protocol implemented in BitchX and other Unix-based clients, and requires special support from Tircproxy to work, because it violates the IRC protocol by replying to a CTCP request with another CTCP request instead of a reply.


DCC TSEND is an enhanced version of DCC SEND, which uses larger packet sizes to speed up transfers. Implementation is otherwise almost identical to traditional DCC SEND.

default gateway

A default gateway is a "last resort" router. That is, the router a machine sends traffic to if it has no better idea of where the traffic should go. Connections to the internet are usually default gateways.


IP is the Internet protocol!


IPF is the "IP Filters" package, used by the BSD family of operating systems to allow fine-grained control over IP traffic (firewalling).

IP Masquerading

IP Masquerading is a variant of IP NAT built into the Linux kernel. It performs on the fly translation of multiple internal IP addresses into a single visible (external) address.


IP NAT is a type of firewalling service, which translates IP addresses on the fly from one source address to another for outgoing packets, and does the reverse for incoming packets.

This allows machines with otherwise invalid (non-unique) IP addresses to communicate with the rest of the Internet with relative ease.


IRC is an acronym for "Internet Relay Chat". See the chapter about IRC basics for more information.


A proxy is an intermediate server, which makes requests on behalf of it's clients. A client doesn't need direct access to a server, if it can communicate with a proxy that does have such access.


A "route" is the path followed by a TCP/IP packet as it passes from it's source to it's destination.


TCP implements a reliable stream oriented full duplex stream between two sockets. TCP ensures that packets are not reordered and retransmits them when they are dropped. It generates and checks a per packet checksum to catch transmission errors.

Text adapted from the tcp(4) manual page in the Linux Programmer's Manual.

tcp wrappers

TCP wrappers is the name of an access control method commonly used on Unix machines to limit access to certain TCP/IP services based on who is requesting them.


User Data Protocol (a.k.a. Unreliable Data Protocol) implements a connectionless, unre- liable datagram packet service. Packets may be reordered or duplicated before they arrive. UDP generates and checks checksums to catch transmission errors.

Text adapted from the udp(4) manual page in the Linux Programmer's Manual.

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