Contents
1. ping
https://changineer.info/network/cisco_ios/cisco_ios_security/cisco_ios_security_icmp.html
https://milestone-of-se.nesuke.com/nw-basic/ip/icmp/
Echo Request (Type 8) / Echo Reply (Type 0)
指定した宛先 IP まで到達できない場合 Destination Unreachable (Type 3)
【Destination Unreachable】は Network Unreachable (code 0) や Host Unreachable (code 1) など、詳細原因毎に個別の Code を持っています。
port-unreach (Port Unreachable) desired port is unreacheable to destination host.
2. frag needed
Path MTU Discovery http://ipnetwork.web.fc2.com/pmtud.html
DF on で送る: ICMPのタイプOx03/コードOx04 (Destination Unreachable/Fragmentation needed and Don't Fragment was set)
破棄される原因となったMTU値(Next-Hop MTU)が含まれています。
3. Linux icmpush
icmpush - ICMP packet builder
- We want to send a packet ICMP Source Quench to host ldg02.hell in response to a packet destinated to host ldg00 with UDP protocol, source port 100 and destination port 200. We mask ourselves as gateway 10.10.10.1: icmpush -sq -sp 10.10.10.1 -prot udp -psrc 100 -pdst 200 -orig ldg00 ldg02.hell