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More Than Machines?

Face to face they stand
Brain to brain
Two-eyed flesh machine
And one-eyed plastic terminal
Interacting systems
Inputting, outputting, precious data.

Face to face they sit
A complex team
Driven to perform
With error-free precision
In a controlled mini-world
Ruled by the god of technology.

Face to face they lie
Worlds apart
Stark, cold plastic eye
Flashing programmed data;
Warm, sensitive flesh eyes
Flashing non-programmable twinkles.
Face to face they are
A new species
Ruled by the god of technology.

Sandra M. Haight

IPTables and ICMP.


To get a list of supported ICMP Types and Codes, use this command:

iptables -p icmp -h

The indented names are the Codes.

Valid ICMP Types:
echo-reply (pong)


To match a simple Ping and Reply:

iptables -a INPUT -p ICMP --type-name echo-request -j LOG --log-prefix «Sent a ping»

iptables -a INPUT -p ICMP --type-name echo-reply -j LOG --log-prefix «Received a reply»


To match against a ICMP Type and Code eg. Destination-unreachable (Type=3) with Host-unreachable (Code=3) you only specify the name for the Code:

iptables -a INPUT -p ICMP --type-name host-unreachable -j LOG --log-prefix «Couldn“t get there»

You could also use the numeric values:

iptables -a INPUT -p ICMP --type-name 3/2 -j LOG --log-prefix «The host is gone»


Click here for the entire list of ICMP Parameters.