D-Link DFL-800-AV-12 User Manual - Page 55

ICMP Services, 3.2.4. Custom IP Protocol Services, Message Type, Destination Unreachable

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3.2.3. ICMP Services Chapter 3. Fundamentals When setting up rules that filter by services it is possible to use the service grouping all_services to refer to all protocols. If just referring to the main protocols of TCP, UDP and ICMP then the service group all_tcpudpicmp can be used. 3.2.3. ICMP Services Internet Control Message Protocol (ICMP), is a protocol integrated with IP for error reporting and transmitting control information. The PING service, for example, uses ICMP to test an Internet connectivity. ICMP messages is delivered in IP packets, and includes a Message Type that specifies the type, that is, the format of the ICMP message, and a Code that is used to further qualify the message. For example, the message type Destination Unreachable, uses the Code parameter to specify the exact reason for the error. The ICMP message types that can be configured in NetDefendOS are listed as follows: • Echo Request: sent by PING to a destination in order to check connectivity. • Destination Unreachable: the source is told that a problem has occurred when delivering a packet. There are codes from 0 to 5 for this type: • Code 0: Net Unreachable • Code 1: Host Unreachable • Code 2: Protocol Unreachable • Code 3: Port Unreachable • Code 4: Cannot Fragment • Code 5: Source Route Failed • Redirect: the source is told that there is a better route for a particular packet. Codes assigned are as follows: • Code 0: Redirect datagrams for the network • Code 1: Redirect datagrams for the host • Code 2: Redirect datagrams for the Type of Service and the network • Code 3: Redirect datagrams for the Type of Service and the host • Parameter Problem: identifies an incorrect parameter on the datagram. • Echo Reply: the reply from the destination which is sent as a result of the Echo Request. • Source Quenching: the source is sending data too fast for the receiver, the buffer has filled up. • Time Exceeded: the packet has been discarded as it has taken too long to be delivered. 3.2.4. Custom IP Protocol Services Services that run over IP and perform application/transport layer functions can be uniquely identified by IP protocol numbers. IP can carry data for a number of different protocols. These protocols are each identified by a unique IP protocol number specified in a field of the IP header, for example, ICMP, IGMP, and EGP have protocol numbers 1, 2, and 8 respectively. NetDefendOS supports these types of IP protocols by using the concept of Custom IP Protocol Services. A Custom IP Protocol service is a service definition giving a name to an IP protocol 55

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When setting up rules that filter by services it is possible to use the service grouping
all_services
to
refer to all protocols. If just referring to the main protocols of TCP, UDP and ICMP then the service
group
all_tcpudpicmp
can be used.
3.2.3. ICMP Services
Internet Control Message Protocol (ICMP), is a protocol integrated with IP for error reporting and
transmitting control information. The PING service, for example, uses ICMP to test an Internet
connectivity.
ICMP messages is delivered in IP packets, and includes a
Message Type
that specifies the type, that
is, the format of the ICMP message, and a
Code
that is used to further qualify the message. For
example, the message type
Destination Unreachable
, uses the Code parameter to specify the exact
reason for the error.
The ICMP message types that can be configured in NetDefendOS are listed as follows:
Echo Request: sent by PING to a destination in order to check connectivity.
Destination Unreachable: the source is told that a problem has occurred when delivering a
packet. There are codes from 0 to 5 for this type:
Code 0: Net Unreachable
Code 1: Host Unreachable
Code 2: Protocol Unreachable
Code 3: Port Unreachable
Code 4: Cannot Fragment
Code 5: Source Route Failed
Redirect: the source is told that there is a better route for a particular packet. Codes assigned are
as follows:
Code 0: Redirect datagrams for the network
Code 1: Redirect datagrams for the host
Code 2: Redirect datagrams for the Type of Service and the network
Code 3: Redirect datagrams for the Type of Service and the host
Parameter Problem: identifies an incorrect parameter on the datagram.
Echo Reply: the reply from the destination which is sent as a result of the Echo Request.
Source Quenching: the source is sending data too fast for the receiver, the buffer has filled up.
Time Exceeded: the packet has been discarded as it has taken too long to be delivered.
3.2.4. Custom IP Protocol Services
Services that run over IP and perform application/transport layer functions can be uniquely
identified by
IP protocol numbers
. IP can carry data for a number of different protocols. These
protocols are each identified by a unique IP protocol number specified in a field of the IP header, for
example, ICMP, IGMP, and EGP have protocol numbers 1, 2, and 8 respectively.
NetDefendOS supports these types of IP protocols by using the concept of
Custom IP Protocol
Services
. A Custom IP Protocol service is a service definition giving a name to an IP protocol
3.2.3. ICMP Services
Chapter 3. Fundamentals
55