Chapter 5 Quiz - Packet Filtering

____ packet filters are useful for completely blocking traffic from a subnet or other network.

Stateless

It is good practice to block ____ access to all internal servers from the public networks.

Telnet

Enabling external hosts to connect to your public servers in the DMZ, but not to hosts in the internal LAN, is an example of filtering on the ____.

destination IP address

The header field that indicates whether the packet is a fragment is ____.

flags

The problem with fragmentation is that because the TCP or UDP port number is provided only at the beginning of a packet, it appears ____.

only in fragments numbered 0

The header field that can contain a security field, which enables the sender to assign a classification level to the packet is ____.

options

A stateless filter compares the header data against its ____ and forwards each packet as a rule is found to match the specifics of that packet.

rule base

One of the first IP header criteria you can filter on is the packet's ____.

source IP address

An 8-bit value is between

00000001 and 11111111

Packets requesting a connection have the ACK bit set to 0; those that are part of an ongoing connection have the ACK bit set to ____.

1

Telnet is most often assigned to use port ____.

23

ICMP message type ____ indicates that a faster route has been located.

5

Using TCP or UDP port numbers can help you filter a wide variety of information, including SMTP and POP e-mail messages, NetBIOS sessions, ____, and Network News Transfer Protocol (NNTP) newsgroup sessions.

DNS requests

The ____ is a structure for organizing Internet names associated with IP

Domain Name System (DNS)

A stateless or stateful packet filter that supports active ____ must allow all traffic coming from TCP Port 20 as well as outbound traffic coming from ports above 1023.

FTP

____ are stand-alone hardware devices with self-contained components that are purpose built to filter out network traffic that does not conform to established rules.

Firewall appliances

____ indicate whether a large number of echo messages are being received.

Firewall logs

The ____ describes the length of the packet header in 32-bit words and is a 4 bit value.

Internet header length

TCP/IP includes ____ which are small manageable chucks of network data.

Packets

The ____ flag tells a host to immediately terminate a connection.

RST