Let us say I create a valid packet (contains telnet request) with TTL value less than the TTL value required to reach the destination IP. Will the computer that receive the IP packet with TTL=1 (become 0 after decrement) in the path to the destination IP send any ICMP response to me?

  • It is always the purpose of all ICMP messages to be triggered by normal IP traffic, in order to report problems. The only exception is ping (i.e. ICMP echo reply is a response to ICMP echo request) – Hagen von Eitzen Aug 6 '15 at 15:09

Yes, the router that decrements the TTL to 0 will discard the packet and send an ICMP time exceeded message (type 11) to the source.

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