TMS zl Management and Configuration Guide ST.1.0.090213

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Glossary

TCP Transmission Control Protocol. Part of the IP protocol suite, TCP allows

applications on networked hosts to create connections to one another and

exchange data. TCP guarantees reliable and in-order data delivery. TCP pro-

tocols include, among many others, HTTP, email, and SSH. For more informa-

tion about TCP, see Request for Comments (RFC) 793 (at http://www.ietf.org/

rfc/rfc0793.txt).

TCP ACK scan A network scanning technique in which attackers or administrators send

unsolicited TCP ACK packets in order to discover unfiltered ports.

TCP FIN scan A network scanning technique in which attackers or administrators send

unsolicited TCP SYN/FIN packets in order to discover open ports.

TCP null flag scan A network scanning technique in which attackers or administrators send a

series of packets with sequence number 0 and no flags in order to discover

open ports.

TCP SYN scan A network scanning technique in which attackers send a SYN packet to a port,

and the host sends an ACK packet if the port is open.

threat level One of five, preconfigured categories that indicates the severity of an attack.

The threat levels are Critical, Severe, Minor, Warning, Informational.

timeout The amount of time the firewall will keep a session open without packets being

exchanged.

TLS Transport Security Layer. The successor to SSL, TLS is a protocol that

provides secure communications through encryption and endpoint

authentication.

TMS OS Threat Management Services operating system. The application that pro-

vides threat management services on the zl module.

TMS VLAN A VLAN that has been associated with a zone on a TMS zl Module in routing

mode.

tools A column in many TMS zl Web browser interface windows that contains some

or all of the following: move icon, to move the entry to a higher or lower

position; edit icon, to edit the entry; delete icon, to delete the entry.

ToS Type of Service. Now called Differentiated Services.

traffic selector Traffic that is allowed over the IPsec SA (VPN tunnel).