TCP Banner Grab
======

This utility will connect (TCP) to ip addresses provide over stdin, optionally
send them a small message, and wait for their response. The response is then
printed along with their IP address on stdout. Status messages appear on stderr.


USING:
-----
make
#echo -e -n "GET / HTTP/1.1\r\nHost: %s\r\n\r\n" > http-req
zmap -p 80 -N 1000 -o - | ./banner-grab-tcp -p 80 -c 100 -d http-req > http-banners.out


OPTIONS:
-----
-c, --concurent         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 -SSn 1000000` and `ulimit -SHn 1000000` to
                        avoid running out of file descriptors (typically capped
                        at 1024).

-p, --port              The port which to connect to hosts on

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

-r, --read-timeout      Read timeout (seconds). Give up on a host if after
                        connecting (and optionally sending data), it does
                        not send any response by this time. Default: 4 seconds.

-v, --verbosity         Set status verbosity. Status/error messages are outputed
                        on stderr. This value can be 0-5, with 5 being the most
                        verbose (LOG_TRACE). Default: 3 (LOG_INFO)

-f, --format            Format to output banner responses. One of 'hex', 'ascii',
                        or 'base64'. 
                        'hex' outputs ascii hex characters, e.g. 48656c6c6f.  
                        'ascii' outputs ascii, without separators, e.g. Hello
                        'base64' outputs base64 encoding, e.g. SGVsbG8=
                        Default is base64.

-d, --data              Optional data file. This data will be sent to each host
                        upon successful connection. Currently, this file does 
                        not allow null characters, but supports up to 4
                        occurances of the current host's IP address, by replacing
                        %s with the string (inet_ntoa) of that host's IP address.