8.3 rsh
Remote shell (rsh or remsh) is one of an entire family of remote UNIX
style commands. The UNIX copy command, cp, becomes rcp. The UNIX
"who is logged in" command, who, becomes rwho. The list continues
and is referred to collectively to as the "r" series commands or the
"r*" (r star) commands.
The r* commands mainly work between UNIX systems and are designed for
interaction between trusted hosts. Little consideration is given to
security, but they provide a convenient user environment.
To execute the "cc file.c" command on a remote computer called delta,
type "rsh delta cc file.c". To copy the "file.c" file to delta, type
"rcp file.c delta:". To login to delta, type "rlogin delta", and if
you administered the computers in a certain way, you will not be
challenged with a password prompt.
8.4 NFS
Network File System, first developed by Sun Microsystems Inc, uses
UDP and is excellent for mounting UNIX file systems on multiple
computers. A diskless workstation can access its server's hard disk
as if the disk were local to the workstation. A single disk copy of
a database on mainframe "alpha" can also be used by mainframe "beta"
if the database's file system is NFS mounted on "beta".
NFS adds significant load to a network and has poor utility across
slow links, but the benefits are strong. The NFS client is
implemented in the kernel, allowing all applications and commands to
use the NFS mounted disk as if it were local disk.
8.5 SNMP
Simple Network Management Protocol (SNMP) uses UDP and is designed
for use by central network management stations. It is a well known
fact that if given enough data, a network manager can detect and
diagnose network problems. The central station uses SNMP to collect
this data from other computers on the network. SNMP defines the
format for the data; it is left to the central station or network
manager to interpret the data.
8.6 X-Window
The X Window System uses the X Window protocol on TCP to draw windows
on a workstation's bitmap display. X Window is much more than a
utility for drawing windows; it is entire philosophy for designing a
user interface.
9. Other Information
Much information about internet technology was not included in this
tutorial. This section lists information that is considered the next
level of detail for the reader who wishes to learn more.
o administration commands: arp, route, and netstat
o ARP: permanent entry, publish entry, time-out entry, spoofing
o IP route table: host entry, default gateway, subnets
o IP: time-to-live counter, fragmentation, ICMP
o RIP, routing loops
o Domain Name System
10. References
[1] Comer, D., "Internetworking with TCP/IP Principles, Protocols,
and Architecture", Prentice Hall, Englewood Cliffs, New Jersey,
U.S.A., 1988.
[2] Feinler, E., et al, DDN Protocol Handbook, Volume 2 and 3, DDN
Network Information Center, SRI International, 333 Ravenswood
Avenue, Room EJ291, Menlow Park, California, U.S.A., 1985.
[3] Spider Systems, Ltd., "Packets and Protocols", Spider Systems
Ltd., Stanwell Street, Edinburgh, U.K. EH6 5NG, 1990.
11. Relation to other RFCs
This RFCis a tutorial and it does not UPDATE or OBSOLETE any other
RFC.
12. Security Considerations
There are security considerations within the TCP/IP protocol suite.
To some people these considerations are serious problems, to others
they are not; it depends on the user requirements.
This tutorial does not discuss these issues, but if you want to learn
more you should start with the topic of ARP-spoofing, then use the
"Security Considerations" section of RFC1122 to lead you to more
information.
13. Authors' Addresses
Theodore John Socolofsky
Spider Systems Limited
Spider Park
Stanwell Street
Edinburgh EH6 5NG
United Kingdom
Phone:
from UK 031-554-9424
from USA 011-44-31-554-9424
Fax:
from UK 031-554-0649
from USA 011-44-31-554-0649
EMail: TEDS@SPIDER.CO.UK
Claudia Jeanne Kale
12 Gosford Place
Edinburgh EH6 4BJ
United Kingdom
Phone:
from UK 031-554-7432
from USA 011-44-31-554-7432