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network:icmp
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ICMP
Internet Control Message Protocol
- Sends messages between two IP hosts
- Checks for errors along link
- Information about communication
| Code | ICMPv4 | ICMPv6 |
|---|---|---|
| 0 | Net unrecheable | No route to destination |
| 1 | Host unrecheable | Communication is administratively prohibited |
| 2 | Protocol unrecheable | Beyond scoupe of source address |
| 3 | Port unrecheable | Address unrecheable |
| 4 | Fragmentation Needed and D.F. | Port unrecheable |
Time Exceeded
- ICMPv4: TTL = 0
- ICMPv6: Hop Limit = 0
ICMPv6 messages
- Router Advertisement (RA)
- Every 200s broadcasted to IPv6 hosts
- Sends Prefix and default gateway link local
- Router: I am an IPv6 router, this is my prefix, use SLAAC/RID to generate a GUA, and this is my default gateway link-local address: …
- Router Solicitation (RS)
- Sent if host needs RA message for IPv6 configuration
- Host: Hey! Is there any IPv6 router here? I need it to generate an IPv6 address.
- Neighbour Solicitation (NS)
- Sent to a host's address to check address uniqueness
- If host receives NA message, it regenerates its IPv6 interface ID (randomly) and checks again
- “Hey you! Are you there? Do you have this address already?”
- Neighbour Advertisement (NA)
- Reply meant for NS messages
- “Hey, I'm using this address already! Use another one!”
network/icmp.txt · Last modified: by 127.0.0.1
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