TCP banner grabber implemented in Go  (experimental)
======

This program will make TCP connections to IP addresses provided on
stdin, optionally send a short message, and wait for responses. Each
response is printed to stdout, along with the responding host's IP
address. Status messages appear on stderr.

USING:
-----
go build banner.go
zmap -p 80 -N 1000 -o - | ./banner -port 80 -concurrent 100 -data http-req > banners.out


OPTIONS:
-----
-concurrent        Number of connections that can be going on at once.
                   This, combined with timeouts, will decide the maximum
                   rate at which banners are grabbed. If this value
                   is set higher than 1000, you should use 
                   `ulimit -SHn 1000000` and `ulimit -SSn 1000000` to
                   avoid running out of file descriptors (typically capped
                   at 1024). Default: 100.

-port              The port which to connect to hosts on. Default: 80.

-timeout           Connection timeout (seconds). Give up on a host if grabber
                   has not completed by this time. Default: 4 seconds.

-format            Format to output banner responses. One of 'hex', 'ascii',
                   or 'base64'. Default: ascii.

-data              Optional data file. This data will be sent to each host
                   upon successful connection. Occurrences of the
                   string '%s' will be replaced with the current
                   target host's address.