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DAVROM CONSULTING Newsletter - Issue # 10 - Dated: Sun May 12 22:33:52 EST 2002




From the desk of David Clark

Well here we are with issue 10 of our newsletter and I would like to
extend a warm welcome to those who have just started to receive copies
of the newsletter. We have taken on quite a few new readers since our
last issue.

The past month's support has been a mixed bag of issues and we have also
recently been speaking with IBM concerning our supporting AIX (IBM's UNIX
platform). DAVROM is able to assist in supplying customers with IBM RS6000
systems as well as AIX support. This coupled with our existing focus on
IBM Intel servers for Caldera OpenServer, OPEN UNIX8 (and Unixware7) and
Linux (Caldera and RedHat), will help us provide customers with high
availability, robust systems.

Once again in this issue, we have provided a link at the top of the
newsletter if you prefer to read the HTML version.

I would like to thank the reader for their time in reading this newsletter.

David.M.Clark


UNIX is UNIX

I often have been asked over the years what the difference between the
various UNIX platforms actually is, how hard is it to swing between
different versions, and is Linux different to UNIX.

Over the years if you stay in the UNIX field you are bound to work on a
variety of UNIX platforms. My background is SCO with Xenix (SCO's first
UNIX) through to OpenServer and Unixware, but I have also worked on and
supported: Dec Ultrix & OSF, SUN Solaris, Dynix, HP-UX, Interactive UNIX,
NEC Astrix, AIX, Free BSD, Linux (various mainstream versions).

From this list you see that Linux "is" UNIX - if you know a UNIX
platform, coming to grips with Linux is not too difficult and as I did,
you will find bits that you love over your preferred UNIX, and bits you
don't particularly like. For me, I prefer SystemV printing but Linux uses
LPD (BSD printing) so .... I adjusted.

The fundamental commands are the same (cp, mv, ls, cat, more, sed, awk, tar)
and are located in directories such as /bin, /usr/bin. Depending on what
packages you include in your installation, files also populate
directories such as /etc and /usr/local. Other than some location
differences (such as where the "rc" startup scripts live and where the
kernel building files are stored) most UNIX systems are not hard to navigate
around.

That being said the /dev device names are often different between
UNIX systems and there are several different names for the default tape
device for example: rct0, rStp0, rmt0, mt0
This coupled with different administration utilities and some different
filesystem layouts does make UNIX versions different enough to warrant
caution when attempting to do major changes on a UNIX system. For run of
the mill administration, there is not too much to worry about except to be
aware that as mentioned earlier, there are different system admin utilities
that help you create users, printers, setup ports, modify network and
system parameters - some examples of these are: scoadmin for SCO,
linuxconf for some Linux, Webmin for Linux, Smit for AIX, SAM for HP-UX.

The fundamental elements are mostly the same and UNIX systems design
ranges from AT&T SystemV to BSD (Berkley) and over the years you see a
merging of both. Some of the differences between the AT&T and BSD (aside
from the West and East coast of the USA) is the location of where they put
their files other than /bin, /usr/bin and /etc. Printing, as mentioned
earlier is one example of quite different locations of files/directories:
BSD uses a configuration file called /etc/printcap and spooling to
/var/spool/lpd, AT&T SystemV uses interface scripts and spools files
located under /var/spool/lp.

The unifying factors of UNIX (that which has given us the Internet we
know and use today) lie in networking with such protocols such as TCP/IP
and its many overlaying network protocols and standards such as SMTP, POP,
PPP, Slip, Arp, Rarp, Telnet, Ftp. The use of Apache, Squid and Samba
are commonly shared programs which aside from which directories they
actually live in, are standard across the UNIX platforms.

It is at this point I would quote what I say to people when asked the
various UNIX platform question - "Yes, they are fundamentally the same,
but there are some distinctive differences and this is due to the
multitude of vendors who have embraced this robust and stable operating
system."


Lone-Tar - how good are your backup scripts

An awesome product that I had the pleasure of being introduced to quite
some years back is Lone-Tar from Cactus International. Lone-Tar offers a
simple to install and manage automated tape backup and recovery
system that protects your system in the event of the unspeakable.....

While we write and install scripts in UNIX/Linux, there can be no real
guarantee given that these scripts may be affected by some condition
that affects the shell environment executing the script. I have lived to
see systems that should have been backing up - actually aren't or at least
aren't backing up that very file/directory that you need to restore.

Lone-Tar offers a great verification process that allows you to keep a
finger on the pulse of how your nightly backups are faring and has a
supoerset of products that cater for network backups and enhanced crash
recovery tools.

Lone-Tar is supported on all of the mainstream UNIX platforms including
Caldera/SCO OpenServer, Caldera/SCO Unixware, AIX, HP-UX, SUN Solaris,
OpenLinux and DG-UX - and many more.

Please contact DAVROM CONSULTING if you would like to find out more
about Lone-Tar for your backup solution.


Some quick bits

Caldera has announced its roadmap for Caldera Volution Manager to be
expanded to support remote management of Windows, AIX, HP-UX and Solaris
systems and beta testing is currently under way for IBM and SUN.

RedHat 7.3 has now been released and offers progressive updates to the
kernel, KDE, Gnome, Apache and have integrated Evolution client (e-mail,
calendar, contacts).


Tech Tip

Telnet testing ports: There are times when telnet can help you determine
if a particular TCP/IP network port is open for network communication.
One example that you can test quite easily is to see if port 25, the
SMTP port, is communicating on your mail server (or even your local UNIX
server). This can be done by:

telnet 192.168.1.1 25

where 192.168.1.1 is the IP address of your UNIX/Linux/E-mail server.

You should see dialogue similar to:

Trying 192.168.1.1...
Connected to 192.168.1.1.
Escape character is '^]'.
220 davrom.com ESMTP Sendmail 8.8.8/SCO5 ready at Sun, 12 May 2002
21:36:25 +1000 (EST)

Here you can simply use the Ctrl-] (control-]) to close the connection.
This is an example output showing that the server 192.168.1.1 is able to
exchange e-mail and if you know the actual input expected by SMTP, you
can send e-mail through this server (conditionally).

Another handy use of telnet-ing to ports is to see if terminal server or
network printer ports are working (Stallion ePipe or HP JetDirect for
example).



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