firewall - Answers hardware or software configured to block unauthorized access to a network
cleanup rule - Answers a packet-filtering rule that comes last in a rule base and covers any packets that
have not been covered by preceding rules
firewall appliances - Answers hardware devices with firewall functionality
firewall policy - Answers an addition to a security policy that describes how firewalls should handle
application traffic, such as web or email applications
proxy server - Answers software that forwards packets to and from the network being protected and
caches Web pages to speed up network performance
rule base - Answers the collection of rules that filter traffic at an interface of a firewall
socket - Answers the end point of computer-to-computer connection defined by an IP address and port
address
state table - Answers a file maintained by stateful packet filers that contains a record of all current
connections
stateful packet filters - Answers filters that are similar to stateless packet filters, except they also
determine whether to allow or clock packets based on information about current connections
stateless packet filters - Answers simple filters that determine whether to allow or block packet based
on information in protocol headers
bastion hosts - Answers computers that are accessible to untrusted hosts
dual-homed host - Answers a computer configured with more than one network interface
failover firewall - Answers a backup firewall that is configured to switch on if the current firewall fails
load-balancing software - Answers software that priorities and schedules requests and then distributes
them to servers in a server cluster based on each server's current load and processing power
many-to-one NAT - Answers a process that uses the source and destination TCP and UDP port addresses
to map traffic between internal and external hosts. Many-to-one NAT is also called Port Address
Translation
Network Address Translation (NAT) - Answers the repacking of packets so that internal IP addresses are
stripped from request to an untrusted network like the Internet
one-to-one NAT - Answers process of mapping one internal IP address to one external IP address
reverse firewall - Answers a device that filters outgoing connections