Specifications

AVM Access Server – Glossary 125
otherwise prohibited by IP masquerading. A forwarding profile consists
of a set of forwarding rules. These forwarding rules determine which IP
packets are forwarded to which servers in the local-area network.
The AVM Access Server always uses IP masquerading on Internet con-
nections. If you want to allow access from the Internet to specific serv-
ers in your LAN, you must use a forwarding profile.
See also “NAT (Network Address Translation)” on page 131.
FTP (File Transfer Protocol)
FTP is a platform-independent protocol—that is, one used by all kinds
of computers and operating systems—for file management and trans-
fer to and from remote computers. FTP builds immediately on TCP, the
OSI Layer 4 (Transport Layer) protocol. The File Transfer Protocol is doc-
umented in RFC 959.
Hash algorithm
A hash function is an algorithm that yields a short value that is practi-
cally unique to a given input. The value of the hash is also called a “di-
gest” of the input. One-way hash algorithms are used in cryptography
to create digital signatures for authentication.
One-way hash algorithms
– The input data can be of any length.
– The output is generally of a fixed length.
– The input data cannot be reconstituted from the output.
– The algorithm must be sufficiently free of collisions: in other
words, the probability of two different input values yielding
the same output must be very small.
Keyed-hash functions
Keyed-hash functions are one-way hash algorithms that use a key
in addition to the variable input data. Keyed-hash functions are
used to generate message authentication codes (MAC). Only
those who hold the same key can generate the same MAC from a
given message. This makes the hash algorithm still safer against
collisions.