User guide

Reference Guide 167
create two additional netmasks under it that separate the first 128
and last 128 addresses into separate identifiable networks.
Subnetting enables a client with a single network to create
multiple networks; the advanced or multiple network
configurations can then be used when setting up the Firebox.
subnet mask
A 32-bit number used to identify which port of an IP address is
masked.
substitution cypher
A method in which the characters of the plain text are substituted
with other characters to form the cipher text.
switch
A device that filters and forwards packets between LAN
segments.
symmetric algorithm
Also called conventional, secret key, and single key algorithms;
the encryption and decryption key are either the same or can be
calculated from one another.
SYN flood attack
A method of denying service to legitimate users by overloading a
network with illegitimate TCP connection attempts.
syslog
An industry-standard protocol used for capturing log information
for devices on a network. Syslog support is included in Unix-
based and Linux-based systems.
TCP (Transmission Control Protocol)
A reliable byte-streaming protocol that implements a virtual
connection. Most long-haul traffic on the Internet uses TCP.
TCP/IP (Transmission Control Protocol/Internet Protocol)
A common networking protocol with the ability to connect
different elements.
TCP session hijacking
An intrusion in which an individual takes over a TCP session
between two machines. A hacker can gain access to a machine