Chapter 10. PC/NFS Clients

10.1. PC/NFS today

The first NFS client for Microsoft DOS or Windows operating systems was developed by Sun Microsystems in the mid-1980s and was called "PC/NFS." The PC/NFS brand name has become a generic term to refer to any product that provides an NFS client feature on Microsoft operating systems. Today, Sun Microsystems has abandoned the PC/NFS business, leaving a fairly competitive field of several vendors of commercial PC/NFS products. There are also some freeware or shareware clients if you look hard enough, but there does not appear to be much development activity around them.

It is beyond the scope of this book to provide a detailed survey of PC/NFS implementations, since they each have unique features, and new releases for each arrive all the time. You can use Internet search engines, Usenet archives from sources like google.com, and as a last resort, queries to Usenet's comp.protocols.nfs newsgroup to get feedback on what products people prefer. You can also look at www.connectathon.org to see which companies test products at the annual Connectathon interoperability testing event. While the Connnectathon web site won't tell you which companies test NFS and which of those have PC/NFS clients, the list of companies is not too long, so you could go to the web site of each and see which have PC/NFS implementations.

When selecting a PC/NFS implementation, your minimum set of required features should include all of the following:

• NFS Versions 2 and 3

• NFS over UDP and TCP

• Some integration with Unix authorization

The last feature amounts to allowing users of PC/NFS clients to use the same password to access the NFS server as they would if they were logging into the system the NFS server resides on. Some PC/NFS clients accomplish this by acting as an NIS client to access the password database from NIS. Most will also integrate by the use of the PCNFSD protocol. This was a protocol invented by Sun Microsystems to facilitate access to Unix password database authorization, as well as printers connected to Unix systems. Note that while support for this protocol is common among PC/NFS implementations, finding a PCNFSD server is not always easy. Ironically, even as of Solaris 8, Solaris doesn't include one. You should expect that the vendor of your selected PC/NFS client can provide a PCNFSD server for the Unix server platform you have deployed. If you have trouble, you might poke around the PC/NFS vendors websites. For example, Hummingbird's ftp.hcl.com FTP server has source and binaries for its HCLNFSD protocol. Note that the HCLNFSD protocol is similar in functionality to the PCNFSD protocol, but has been enhanced to work better with the Hummingbird PC/NFS product. HCLNFSD is not compatible with the PCNFSD protocol. While several non-Hummingbird PC/NFS implementations support HCLNFSD in addition to Hummingbird, if you have a PC/NFS client that supports only the PCNFSD protocol, Hummingbird's HCLNFSD implementation will be of no use. If you are in this predicament, try using a search engine to find PCNFSD source code or binaries. For example, typing this query into www.google.com:

source code for pcnfsd

turned up this URL:

http://www.sunfreeware.com/programlist.html

which had both source and binaries (Solaris 2.6, SPARC) for PCNFSD. Obviously, URLs come and go, so don't be surprised if you find PCNFSD somewhere else.

Advanced and interesting features of some PC/NFS implementations include:

• Kerberos V5 security for NFS mounts. This allows clients to access NFS servers that share filesystems via Kerberos V5 security only.

• RPC/DH security for NFS mounts. This allows clients to access NFS servers that share filesystems via RPC/DH security only.

• Integration with NIS+.

You should expect that future PC/NFS implementations will add features like NFS Version 4 and integration with LDAP (so that the Unix authentication database in LDAP can be accessed).