User guide

Reference Guide 169
Transport Layer Security Protocol (TLSP)
ISO 10736, draft international standard.
transposition cipher
A cipher in which the plain text remains the same but the order of
the characters is transposed.
triple-DES
An advanced form of encryption using three keys rather than one
or two. It is roughly as secure as single DES would be if it had a
112-bit key.
trust
Confidence in the honesty, integrity, or reliability of a person,
company, or other entity.
Trusted interface
The interface on the Firebox that connects to the internal network,
which should be protected to the maximum practical amount.
Trusted network
The network behind the firewall that must be protected from the
security challenge–usually, the Internet.
tunnel
An entity through which one network sends its data by way of
another network’s connections. Tunneling works by
encapsulating a network protocol within packets carried by the
second network. For example, Microsoft’s PPTP technology
enables organizations to use the Internet to transmit data across a
virtual private network (VPN). It does this by embedding its own
network protocol within the TCP/IP packets carried by the
Internet.
twisted-pair cable
A cable used for both network and telephone communications.
Also known as UTP (unshielded twisted pair) and 10BASE-T/
100BASE-T cable.
UDP (User Datagram Protocol)
A connectionless protocol. Used less frequently for long-distance
connections, largely because it lacks TCP’s congestion control
features. Used quite heavily in local area networks for NFS.