determine if tcp port is open

nc -zw2 www.example.com 80 && echo open

@putnamhill, no need if statement in that case. && is a AND and || is a OR

By: sputnick

2009-12-07 21:35:25

echo netcat nc

5 Alternatives + Submit Alt

determine if tcp port is open
This is sample output - yours may be different.
5

lsof -i :22

bucciarati · 2011-03-11 16:48:37 5
determine if tcp port is open

for udp nmap -sU -p 80 hostname
This is sample output - yours may be different.
4

nmap -p 80 hostname

solarislackware · 2009-12-08 20:25:28 3
determine if tcp port is open

Requires netcat.
This is sample output - yours may be different.
2

if (nc -zw2 www.example.com 80); then echo open; fi

putnamhill · 2009-12-07 20:04:55 3
determine if tcp port is open
This is sample output - yours may be different.
-3

nc <ip> <port> -v

andreisid · 2011-03-11 16:37:09 3
determine if tcp port is open
This is sample output - yours may be different.
-3

fuser -n tcp -s <port> && echo "+open"

cicatriz · 2011-03-11 19:06:10 3

What Others Think

@sputnick, thanks for the && tip. This came from a script of mine that includes an else clause. Does look much cleaner with the and construct.

putnamhill · 750 weeks and 4 days ago

poor man's nmap...nice!

bubo · 750 weeks and 2 days ago

nc is absolutely not a poor mans nmap. If anything, nmap is a wrapper for a watered down netcat. Things netcat can do, which nmap cannot. #1 Assist in hard drive cloning across the network. #2 Be a telnet server #3 Be a chat server #4 Transfer files #5 Be a web server #6 Proxy dns requests #7 Proxy ssh requests ...

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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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