- What are 5 types of errors handled by ICMP messages?
- What port is ICMP?
- Does ICMP use IP?
- Should I disable ICMP?
- What does ICMP Type 11 Code 0 denote?
- What is ICMP unreachable?
- When a router discards a packet it sends the ICMP message to?
- What is the purpose of ICMP?
- Why ICMP has no port number?
- Which layer protocol is ICMP?
- What are the different types of ICMP messages?
- When a router Cannot route a datagram datagram is discarded and sends a message to source?
- Which protocol is used by Traceroute?
- What ICMP types should I allow?
What are 5 types of errors handled by ICMP messages?
ICMP uses the source IP address to send the error message to the source (originator) of the datagram.
Five types of errors are handled: destination unreachable, source quench, time exceeded, parameter problems, and redirection (see figure1)..
What port is ICMP?
ICMP has no ports and is neither TCP nor UDP. ICMP is IP protocol 1 (see RFC792), TCP is IP protocol 6 (described in RFC793) and UDP is IP protocol 17(see RFC768). UDP and TCP have ports, ICMP has no ports, but types and codes.
Does ICMP use IP?
ICMP uses the basic support of IP as if it were a higher-level protocol, however, ICMP is actually an integral part of IP. Although ICMP messages are contained within standard IP packets, ICMP messages are usually processed as a special case, distinguished from normal IP processing.
Should I disable ICMP?
The Problem. Many network administrators feel that ICMP is a security risk, and should therefore always be blocked at the firewall. It is true that ICMP does have some security issues associated with it, and that a lot of ICMP should be blocked. But this is no reason to block all ICMP traffic!
What does ICMP Type 11 Code 0 denote?
ICMP Type 11: Time Exceeded Codes. Time Exceeded Code. Description. 0. Time to Live exceeded in transit.
What is ICMP unreachable?
The ICMP Destination Unreachable message is sent by a router in response to a packet which it cannot forward because the destination (or next hop) is unreachable or a service is unavailable.
When a router discards a packet it sends the ICMP message to?
When some fragments are lost in a network then the holding fragment by the router will be droped then ICMP will take source IP from discarded packet and informs to the source, of discarded datagram due to time to live field reaches to zero, by sending time exceeded message.
What is the purpose of ICMP?
ICMP (Internet Control Message Protocol) is a protocol that network devices (e.g. routers) use to generate error messages when network issues are preventing IP packets from getting through.
Why ICMP has no port number?
The ICMP packet does not have source and destination port numbers because it was designed to communicate network-layer information between hosts and routers, not between application layer processes. Each ICMP packet has a “Type” and a “Code”. The Type/Code combination identifies the specific message being received.
Which layer protocol is ICMP?
So ICMP processing can be viewed as occurring parallel to, or as part of, IP processing. Therefore, in the topic on TCP/IP-based layered network, ICMP is shown as a layer 3 protocol. ICMP is probably most well known as the message protocol used for the command.
What are the different types of ICMP messages?
Internet Control Message Protocol (ICMP) ParametersType 0 — Echo Reply.Type 1 — Unassigned.Type 2 — Unassigned.Type 3 — Destination Unreachable.Type 4 — Source Quench (Deprecated)Type 5 — Redirect.Type 6 — Alternate Host Address (Deprecated)Type 7 — Unassigned.More items…•
When a router Cannot route a datagram datagram is discarded and sends a message to source?
6. When a router cannot route a datagram or host cannot deliver a datagram, the datagram is discarded and the router or the host sends a ____________ message back to the source host that initiated the datagram. Explanation: Router sends destination unreachable message if the destination is not found.
Which protocol is used by Traceroute?
Internet Control Message Protocol (ICMP)It uses a series of Internet Control Message Protocol (ICMP) Echo messages to determine: Whether a remote host is active or inactive. The round-trip delay in communicating with the host.
What ICMP types should I allow?
The only essential ICMP traffic you need to allow in and out of your firewall is Type 3 and Type 4. Everything else is either optional or should be blocked. Notes: To send ping requests, allow type 8 OUT and type 0 IN.