Q. How do I find out which ports are opened on my own server? How do I run port scanning using nc command?
A. It may be useful to know which ports are open and running services on a target machine. You can use nmap command for port scanning.
How do I use nc to scan Linux / UNIX / Windows server port scanning?
If nmap is not installed try nc / netcat command. The -z flag can be used to tell nc to report open ports, rather than initiate a connection.
Run nc command with -z flag. You need to specify host name / ip along with the port range to limit and speedup operation.
$ nc -z vip-1.vsnl.nixcraft.in 1-1023
Output:
Connection to localhost 25 port [tcp/smtp] succeeded! Connection to vip-1.vsnl.nixcraft.in 25 port [tcp/smtp] succeeded! Connection to vip-1.vsnl.nixcraft.in 80 port [tcp/http] succeeded! Connection to vip-1.vsnl.nixcraft.in 143 port [tcp/imap] succeeded! Connection to vip-1.vsnl.nixcraft.in 199 port [tcp/smux] succeeded! Connection to vip-1.vsnl.nixcraft.in 783 port [tcp/*] succeeded! Connection to vip-1.vsnl.nixcraft.in 904 port [tcp/vmware-authd] succeeded! Connection to vip-1.vsnl.nixcraft.in 993 port [tcp/imaps] succeeded!
See also
- Linux: Scanning network for open ports
- netcat / nc and nmap command man page
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{ 3 comments… read them below or add one }
I had to add verbosity (-v) to get the output as above. By default my version displayed nothing. (Talking of that, I couldn’t figure out how to get it’s version…)
Hello,
I run this command on my ubuntu server but I am not getting that kind of output as you provided here. When I am using -z option that time it is not giving any kind of output. If use -t or option then it is giving output for port range 1-100 .. output is :SSH-2.0-OpenSSH_5.1p1 Debian-5ubuntu1 only.
I.e it is scanning for port 22 only.
Could you please tell me why options are not running on Ubuntu ?
I had to add -v for it to work for me
nc -z -v 127.0.0.1 22
Connection to 127.0.0.1 22 port [tcp/ssh] succeeded!