LISTEN(1)                  Linux Programmer's Manual                 LISTEN(1)

       listen - monitor AX.25 traffic

       listen [-8] [-a] [-c] [-h] [-i] [-p port] [-r] [-t] [-v]

       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,
       Rose, 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.
       JNOS style NET/ROM node polls are also displayed.

       Listen can use colors to make the output more readable. The ncurses
       library is used to accomplish this.  Color support defaults to being
       disabled, and the -c parameter is used to enable it.

       -8        Indicates that the terminal is capable of printing 8-bit
                 characters. This parameter is required for the -i parameter
                 to work.

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

       -c        Enable color support.

       -h        Dump the data portion of the packet in both hexadecimal and
                 ASCII. The default is to display data as ASCII only.

       -i        Map IBM codepage 437 characters 128-158 to their ISO-Latin-1
                 equivalents.  This is a hack for scandinavian users. This
                 parameter is only valid when used with the -8 and -c

       -p port   Monitor only those frames received on a particular port, by
                 default all AX.25 devices are monitored.

       -r        Dump the data portion in a "readable" fashion, which is more
                 suitable for tracing plaintext AX.25 traffic. CR-LF
                 conversion is done.

       -t        Displays a timestamp with each packet received.

       -v        Display the version.


       call(1), mheard(1), beacon(1), ax25(4), netrom(4), rose(4),

       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.

       Alan Cox GW4PTS <>
       Jonathan Naylor G4KLX <>
       Phil Karn KA9Q <>
       Heikki Hannikainen OH7LZB <>
       Scott Miller N1VG <>

Linux                           27 August 1996                       LISTEN(1)