3.2.4. Custom IP Protocol Services
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 pack-
et. 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 identi-
fied 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 the concept of Custom IP Protocol Services.
Basically, a Custom IP Protocol service is a service definition giving a name to an IP protocol num-
ber. Some of the common IP protocols, such as IGMP, are already pre-defined in the system config-
uration.
Similar to the TCP/UDP port ranges described previously, a range of IP protocol numbers can be
used to specify multiple applications for one service.
Note
The currently assigned IP protocol numbers and references are published by the Inter-
net
Assigned
Numbers
tp://www.iana.org/assignments/protocol-numbers
Authority
(IANA)
and
38
Chapter 3. Fundamentals
can
be
found
at
ht-