$ nslookup Default Server: varun.cse.iitb.ernet.in Address: 144.16.111.26 > bhairav.ee.iitb.ernet.in Server: varun.cse.iitb.ernet.in Address: 144.16.111.26 Name: bhairav.ee.iitb.ernet.in Address: 144.16.100.100 > www.ibm.com Server: varun.cse.iitb.ernet.in Address: 144.16.111.26 Non-authoritative answer: Name: www.ibm.com Address: 204.146.18.33 > 202.54.1.1 Server: varun.cse.iitb.ernet.in Address: 144.16.111.26 Name: bom2.vsnl.net.in Address: 202.54.1.1 } \nsld{What is NFS?} \bi \im A distributed file system that provides transparent access to remote disks. \im Allows to centralize administration of disks. \ei Why do we need NFS ? \bi \im To ensure that files (e.g. home areas) a user needs are accessible from local machines. \im No need to copy files to the local machine. \ei \nsld{NFS server} Important Programs include \bi \im {\bf portmap:} Facilitates initial connection \im {rpc.mountd:} \bi \im Answers NFS access requests \im Answers file system mount requests \im Reads the /etc/exports file to determine which file systems to mount \ei \im {\bf rpc.nfsd:} \bi \im Handles client file system requests \im Allows the clients read-only and read-write access to file hierarchy of the server machine. \ei \ei \nsld{/etc/exports File} \bi \im Access control list for exporting \im Sample exports file {\small \begin{verbatim} /home oswpc-01.cse.iitb.ernet.in(rw) /home/mtech/rony ankita.cse.iitb.ernet.in(rw,no_root_squash)The directory /home can be mounted on oswpc-01 in read-write mode. /home/mtech/rony can be mouted in read-write mode on ankita Root on ankita can modify the contents. If the option no_root_squash is not specified then only a user with the same UID can modify the contents of the exported directory.