scanport
For a given TCP port, try connecting to every IP address on the LAN and tell which ones succeed. Attempts connections in parallel.
Arguments are: TIMEOUT SUBNET PORT. TIMEOUT is seconds (floating point), the maximum amount of time to wait for each connection.
Examples:
time ./scanport 0.5 10.60.3.0/24 80
for i in $(seq 1 32); do scanport 0.5 10.60.$i.0/24 80; done
To build:
g++ -Wall -Werror -std=c++11 -s -O3 scanport.cpp -lpthread -o scanport