port scan using parallel

seq 1 255 | parallel -j+0 'nc -w 1 -z -v 192.168.1.{} 80'
It takes over 5 seconds to scan a single port on a single host using nmap time (nmap -p 80 192.168.1.1 &> /dev/null) real 0m5.109s user 0m0.102s sys 0m0.004s It took netcat about 2.5 minutes to scan port 80 on the class C time (for NUM in {1..255} ; do nc -w 1 -z -v 192.168.1.${NUM} 80 ; done &> /dev/null) real 2m28.651s user 0m0.136s sys 0m0.341s Using parallel, I am able to scan port 80 on the entire class C in under 2 seconds time (seq 1 255 | parallel -j255 'nc -w 1 -z -v 192.168.1.{} 80' &> /dev/null) real 0m1.957s user 0m0.457s sys 0m0.994s

3
By: devrick0
2011-06-11 14:40:51

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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