ICMP

On systems without the BSD routing socket, gated listens to ICMP messages received by the system. Currently gated only does processing on ICMP redirect packets, but more functionality may be added in the future, such as support for the router discovery messages. Processing of ICMP redirect messages is handled by the redirect statement.

Currently the only reason to specify the icmp statement is to be able to trace the ICMP messages that gated receives.

The ICMP statement

icmp { traceoptions trace_options ; }

traceoptions trace_options ;
Specifies the tracing options for ICMP. (See Trace Statements and the ICMP specific tracing options below.)

Tracing options

Packet tracing options (which may be modified with detail and recv):

packets

All ICMP packets received.

redirect

Only ICMP REDIRECT packets received.

routerdiscovery

Only ICMP ROUTER DISCOVERY packets received.

info

Only ICMP informational packets, which include mask request/response, info request/response, echo request/response and time stamp request/response.

error

Only ICMP error packets, which include time exceeded, parameter problem, unreachable and source quench.