LISTEN(1)

NAME
listen - monitor AX.25 traffic

SYNOPSIS
listen [-d dev] [-p]

DESCRIPTION

Listen uses SOCK_PACKET facilities to provide a network monitor of all AX.25 traffic heard by the system. Since KISS is implicitly promiscuous no special driver configurations are needed.

This version displays standard AX.25, PE1CHL extended AX.25, NET/ROM, ARP, IP, ICMP, TCP and UDP. It also displays IP, TCP, ICMP, TCP and UDP encapsulated within NET/ROM frames. The program also displays AX.25 and IP encapsulated within an IP frame, but see RFC1326 for reasons not to do so.

Listen makes an attempt at decoding some of the more common routing protocols. RSPF and RIP (both ``normal'' and G8BPQs RIP98) are traced.

OPTIONS

-d dev
    Monitor only those frames received on a particular device, by default all AX.25 devices are monitored.

-p  Allow for the monitoring of outgoing frames as well as incoming ones.

SEE ALSO
call(1), mheard(1), beacon(1), ax25(4), netrom(4), axattach(8).

BUGS
Listen does not validate the checksums of frames that support them (ie IP), therefore corrupt frames will be displayed with bogus values. The MSS of a TCP frame that contains that option is not displayed.

AUTHORS
Alan Cox GW4PTS <A.Cox@swansea.ac.uk>
Jonathan Naylor G4KLX <jsn@cs.nott.ac.uk>
Phil Karn KA9Q <karn@qualcomm.com>