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Top Forums UNIX for Dummies Questions & Answers How do you check whether a port currently being used? Post 302315860 by zaxxon on Wednesday 13th of May 2009 11:15:49 AM
Old 05-13-2009
Hi, please open a new thread next time instead of digging out this old one.

There is some information to your question already in this thread.
If you don't have an entry in your /etc/services, you can try with the command (if available) "lsof" if you can see what uses this port. Also you can check with netstat -a for example if it is up and what status it has.
For blocking ports you might want to use a firewall; depending on your system on Linux you could use ipchains/iptables.
 

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nfs_portmon(5)							File Formats Manual						    nfs_portmon(5)

NAME
nfs_portmon - enable/disable the NFS server's source port verification check VALUES
Failsafe Default Allowed values DESCRIPTION
controls some security checking that the NFS server can do in an attempt to enforce integrity on the part of its clients. The NFS server can check to see whether the source port from which a request was sent is a reserved port; a reserved port is a port whose port number is less then 1024. For BSD-based systems, these ports are reserved for processes being run by privileged users. This checking helps prevent users from writing their own RPC-based applications which defeat the access checking that the NFS server uses. Who Is Expected to Change This Tunable? The distributed file system administrator should examine the value of this parameter if he or she wishes to prevent malicious users from gaining access to files by using an NFS server they would not ordinarily be able to access. Restrictions on Changing The tunable is dynamic; any change will take effect immediately on the running system. The reserved port notion is not universally supported. Therefore, interoperability problems might result if this checking is enabled. What Are the Side Effects of Enabling This Check? Some NFS clients may not be able to connect to the NFS server. WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of HP-UX. Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation, some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun- able values, consult the documentation for the kernel software being installed. For information about optional kernel software that was factory installed on your system, see at AUTHOR
was developed by Sun Microsystems, Inc. SEE ALSO
kctune(1M), sam(1M), gettune(2), settune(2). Tunable Kernel Parameters nfs_portmon(5)
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