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Glossary User’s Manual 155
Fragment
When a data is too large to fit into one packet it can be divided into multiple
packets (also fragments). Typically the header information such as source port,
destination port, ICMP type is only stored in the start of the packet (i.e. the first
packet).
This is a problem since a rule filtering a source port (for instance port 80) will
always fail when a fragment data packet is inspected because the source port was
not in the header (except for the first data packet which had all of the required
information.)
Freeware
This is software that is given away free by the author. The author still retains the
copyright however so you cannot resell or alter the software without first
obtaining permission from the author.
FTP
File Transfer Protocol creates a virtual connection over TCP/IP which allows file
sharing. For example an FTP client (your computer) asks an FTP server (a remote
computer with files you want) for permission to transfer files. You will often need
a login ID and password to access the FTP server though many servers have a
guest account under the login ID “anonymous” and password of the users email
address.
See RFC959.
Firewall
The networking hardware device that links two different networks. Usually this
device (such as a router) will be identified with an IP address. To reach the other
network your computer must know the IP address of the firewall so it can send the
information through it to the remote network.
G.DMT
Discrete Multitone Technology is a DSL line modulation standard. Sometimes
referred to as “full rate” ADSL.
G.Lite
Also referred to as “DSL Lite”, “Universal DSL”, or “splitterless ADSL”, is a
SDSL Line Modulation Standard. It requires no filters or splitters and supports
speeds up to 1.5 Mbps download and 512Kbps upload.
Hacker