ICMP Destination Unreachable (Host administratively
Feb 15, 2018 Define Firebox Global Settings - WatchGuard Host Unreachable Select this check box to allow ICMP Host Unreachable messages. Your network usually sends these messages when it cannot use a host or service. Port Unreachable Select this check box to allow ICMP Port Unreachable messages. A host or firewall usually sends these messages when a network service is not available or is not allowed. RFC 792 - Internet Control Message Protocol ICMP Fields: Type 3 Code 0 = net unreachable; 1 = host unreachable; 2 = protocol unreachable; 3 = port unreachable; 4 = fragmentation needed and DF set; 5 = source route failed. Checksum The checksum is the 16-bit ones's complement of the one's complement sum of the ICMP message starting with the ICMP … Disabling unreachables breaks PMTUD - PacketLife.net Oct 09, 2008
ICMP type 3, Destination unreachable message
Feb 23, 2014 [SOLVED] Destination host unreachable - CentOS Aug 04, 2011
linux - What -A INPUT -j REJECT --reject-with icmp-host
As I understand it, "request timeout" means the ICMP packet reached from one host to the other host but the reply could not reach the requesting host. There may be more packet loss or some physical issue. "destination host unreachable" means there is no proper route defined between two hosts. linux - What -A INPUT -j REJECT --reject-with icmp-host If you do not specify which ICMP message to reject with, the server by default will send back ICMP port unreachable (type 3, code 3).--reject-with modifies this behaviour to send a specific ICMP message back to the source host.