tyt12fi.htm

一个学习tcp/ip协议的教程

   in 18.3 seconds elapsed time,

   4 packets (2.00%) dropped by beast

Sent:  10 packets/sec, 912 bytes/sec

Recd:   9 packets/sec, 862 bytes/sec</FONT></PRE><P>The rusers program gives you an idea of who is logged into remote machines. A typical output is the following:<BR><PRE>

<FONT COLOR=#000080>$ rusers

beast.tpci.com       tparker  bsmallwood  rmaclean

merlin.tpci.com      ychow  etreijs  tgrace

tpci_hpws3.tpci.com  tparker  sysadm

tpci_hpws4.tpci.com  pepper</FONT></PRE><P>As shown, the output from the rusers program includes the machine name and the list of users on that machine. Some implementations support options for rusers, whereas some have slightly differing output.<BR><BR><A ID=E68E110 NAME=E68E110></A><H3 ALIGN=CENTER><CENTER><FONT SIZE=5 COLOR=#FF0000><B>Configuring NFS</B></FONT></CENTER></H3><BR><P>Many people love using the NFS service when they are faced with it as a user but are scared to configure it when acting as a system administrator. The general assumption is that the process must be convoluted, complex, and require a lot of knowledge about the operating systems. For this reason, many people don't bother with NFS, which is a shame because it is one of the most useful services TCP/IP has to offer. As you see in this section, it is not difficult to implement an NFS network.<BR><P>I configure NFS on two different operating systems to show the general process. I use an SCO UNIX machine as an example of a UNIX installation, and a Windows for Workgroups system to show setting up a client and server NFS PC system. I start with the UNIX machine, because UNIX is most often associated with NFS servers.<BR><BR><A ID=E69E159 NAME=E69E159></A><H4 ALIGN=CENTER><CENTER><FONT SIZE=4 COLOR=#FF0000><B>Configuring UNIX as an NFS Server</B></FONT></CENTER></H4><BR><P>The NFS service makes extensive use of the RPC service. For this reason, the RPC server daemon must be running for NFS to be implemented. On some UNIX systems you can check whether RPC is active by issuing this command at the shell prompt:<BR><BR><PRE>

<FONT COLOR=#000080>rpcinfo -p</FONT></PRE><P>You should see a list of all the RPC servers currently running on your machine. If RPC is running properly, you see four rpcbind listings (two for UDP and two for TCP) and an entry for pcnfsd, the NFS daemon. This command doesn't show all this output for some versions of UNIX, including SCO UNIX.<BR><P>For SCO UNIX, NFS is started and stopped by a script called /etc/nfs. This can be linked into the startup routines to load NFS automatically when the system boots by linking the /etc/nfs file to the file /etc/rc2.d/Sname. To shut down NFS properly, you also need to link /etc/nfs to the file /etc/rc0.d/Kname. (On other UNIX implementations the filenames change, but the general approach is the same.) If you want to start and stop the NFS daemon manually, you can do this with these commands:<BR><PRE>

<FONT COLOR=#000080>/etc/nfs start

/etc/nfs stop</FONT></PRE><P>The /etc/nfs command starts up and shuts down the NFS server daemon when the appropriate command is issued. When you issue the start command, the daemons that are activated are echoed to the screen:<BR><PRE>

<FONT COLOR=#000080>$ /etc/nfs start

Starting NFS services: exportfs mountd nfsd pcnfsd biod(x4)

Starting NLM services: statd lockd</FONT></PRE><P>With a stop command, you see a message that the daemons and server are shut down:<BR><PRE>