YAPS

Yet Another Port Scanner

TIP: you can leave the second address field blank, and it will only scan the first address
TIP: addresses can be either DNS names, or IPs, although if you are using a start and end address, then IPs rather than DNS names would problably make more sense

YAPS supports the following command line args
    -start
    -start_address <ip.address>
    -stop_address <ip.address>
    -start_port <port>
    -stop_port <port>
    -timeout <milliseconds>
    -sim <num_simultaneous>
    -resolve <y|n>
    -html
    -prefs <prefs_filename_override>
eg
    yaps -start -resolve y -start_port 135 -stop_port 135 -start_address 192.168.0.1 -stop_address 192.168.0.254 -sim 100 -timeout 100

YAPS on Windows XP with Service Pack 2
On Windows XP Service Pack 2, YAPS may appear to be very slow at scanning. This is due to a Microsoft limiting the number of outgoing TCP connection attempts. Google for 'Event ID 4226' for more information.