ICMP (ping, trace)is a layer 3 protocol suite within the TCP/IP suite, doesnt test any layer 4 or above functions, therefore, it has no TCP/UDP layer 4 port number. The sub protocols within it do. You can block echo replies by closing port 7.
We Just Added Support for VPN Over ICMP & DNS | CactusVPN Sep 20, 2018 Protocol Header Cheetsheets — Pingfu IPv4 Header. Notes. The Internet Protocol (IPv4) is defined in RFC 791 which specifies the format of the header.; IHL (Internet Header Length) is 4 bits long and specifies the header length in increments of 32 bits (DWORD). The IHL field can hold values from 0 (Binary 0000) to 15 (Binary 1111).So the longest the IP header size can be is upto 480 bits, which is 60 bytes.
The 192.168.1.0/24 route is different though. It looks like it doesn't exist at all, because when pinging from, for example 192.168.1.99, the traffic arrives correctly but instead of being sent back from 10.250.0.3 over the link on interface eth2.620 the Ubiquiti router tries to send them over …
and sent the ICMP echo request with the default of 32 bytes of data. The total length of the ping packet is 74 bytes. The packet can be broken into the following protocol elements: Ethernet Header; IP Datagram(packet) IP Header; IP Data Internet Control Message Protocol (ICMP) - GeeksforGeeks
Mar 28, 2019
Why disabling ICMP unreachables is a bad thing