Finding Open ports

[Ronit_1]

I want to find out the number of ports they r open and in use in HPUX 11i system.

[Patrick Wallek]

You would be best served by getting the tool 'lsof' and installing it. That will most easily allow you to do this.

You can get lsof from:
http://hpux.connect.org.uk/hppd/hpux/Sysadmin/lsof-4.78/

You can also use the 'netstat' command to see what is listening.

A 'netstat -a' will show a lot of network information. Have a look at 'man netstat' for more information.

[Anshumali]

May be you want to try nmap as well....search google for this

[Kapil Jha]

Still in lsof you will have to grep a port you looking for.
I suppose there is no command which could give u a list of open and used port.
Br,
Kapil

[Anshumali]

Kapil: I suppose there is no command which could give u a list of open and used port.
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There are lot many tools like nmap and satan..which could give you the ports opened from your machine to the server.(It may be illegal to use in your country may be) but They are widely used in network scanning for open ports. ( Blackheads may call it back door;) )

If that is not what you need you can still use the lsof with decent combination of UNIX supplied commands (grep, netstat)on the server itself. Combining options available in UNIX doesn't deface the value of a particular utility or command.It increases the power, thats why i love UNIX....

[Ralph Grothe]

As said, there are numerous tools for port scanning.
One of the most versatile is nmap
which you can use if you not only want to check from a different host which ports are serviced by your host, but also which are open or closed (but reachable), viz. not filtered by a firewall.
nmap can also perform many sorts of stealth scans, or even scans that pretend to be coming from a different host (idle scan) which could be helpful in tricking some state inspecting firewalls or intrusion detection systems.
Where nmap lacks a bit however, sometimes can be where UDP port scans are of interest because it might not be able to tell whether a UDP port really is open or filtered.
For determining a real open UDP port the scanner would have to send a valid UDP datagram for the particular UDP service which would require knowledge of too many protocols at application layer, and catch a response datagram.
But there are other port scanners that partly cover this for the more general services that use UDP.

If you are only interested to quickly check on your host locally ports that service, the netstat command is more than sufficient
e.g.

$ netstat -an|awk '$NF~/LISTEN/{print a[split($4,a,".")]}'|sort -n