nfs_portmon.5 (2010 09)

nfs_portmon(5) nfs_portmon(5)

(Tunable Kernel Parameters)

NAME

nfs_portmon - enable/disable the NFS server’s source port veriﬁcation check

VALUES

Failsafe

Default

Allowed values

Minimum: 0 - disable checking

Maximum:

1 - enable checking

DESCRIPTION

nfs_portmon 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

nfs_portmon 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 parame-

ter values. After installation, some tunable parameters may no longer be at the default or recommended

values. For information about the effects of installation on tunable values, consult the documentation for

the kernel software being installed. For information about optional kernel software that was factory

installed on your system, see HP-UX Release Notes at http://www.hp.com/go/hpux-core-docs

AUTHOR

nfs_portmon was developed by Sun Microsystems, Inc.