Administrator's Guide
Appendix D. Definitions of terms
AFS, Andrew File System
AFS is a more secure way of distributing file systems over a network. If files are
mounted over the Internet, AFS is fairly secure. Normally, AFS uses Kerberos for se-
curity management.
ARP
ARP, Address Resolution Protocol, is a protocol for mapping an IP address to a physical
machine address in the local network. A thorough description of ARP can be found in
RFC 826.
Broadcast
Broadcast is a method of sending packets when you don’t know the actual recipient.
The packets are sent to all computers on the network.
Each network has a network address (the first address of the IP interval) and a broad-
cast address (the last address of the IP interval). On the network 192.168.0.0/24
(192.168.0.0-192.168.0.255), 192.168.0.255 is the broadcast address. When a computer
wants to address all computers on the network, like when a Windows computer wants
to map the resources, it sends a request to the broadcast address. All computers on the
network receive this request and decides if they should reply.
Client program
A client program is one that the user runs on her computer. A client program connects
to a server. One example of a client program is Mozilla (a web browser). One benefit of
dividing up a service into server and client programs is that the server program can be
run on a larger computer with better resources, and the users do not have to make their
own copies of the databases. This allows the client programs to be run on less powerful
computers.
Cracker
A person who breaks into computer systems and commits other criminal acts using a
computer.
Daemon program
A daemon program is a server program for a service. This kind of program waits for
and manages external calls. A typical example is FTP. A user starts his FTP client. The
client connects to the FTP server. Now the user can transfer files to his own computer
or to the server. See Server.
Denial of Service, DoS
A type of attack that tries to block a network service by overloading the server.
DHCP
DHCP, Dynamic Host Configuration Protocol, is a protocol for handing out IP ad-
dresses and other configuration information to computers without having to log on to
every single machine. Instead, the computers themselves send out requests about this
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