Digital certificates have become an essential part of
Internet commerce, and are widely used to verify the identity
of clients and servers. All digital certificates contain an
expiration date which most client and server applications will
check before using the certificates contents. If a client or
server application detects that a certificate has expired, one
or more implementation specific actions (e.g., abort
connection, check or update a revocation list, alert user,
etc.) are typically performed.

When a web browser encounters an expired certificate, the
browser will normally present the user with a warning message
indicating that the certificate has expired. Some browsers will
continue connecting to the site after presenting the user with
the warning, while others will prompt the user with a dialog
box requesting their approval to proceed. These warnings are
extremely confusing for the typical web user, and cause most
users to question the authenticity of the site they are
attempting to view.

Continua”manage SSL certificate expiration with ssl-cert-check”

SELinux can sometimes get
in your way. For example, I have had typical services, such as Apache, appear
to start up correctly, but remain inaccessible from the outside world because
I forgot to allow the apache user rights to open that port or maybe my distro
forgot about it. Before you turn off SELinux make sure you know why
you are turning it off and the security concerns you might be opening yourself
up to.

Continua”How to turn off SE Linux”

I found this command useful in finding out which top 10 processes are hogging my CPU resources. Note that this command is specific to the Red Hat flavor of Linux. See the man page for ps for the correct output format to use for your specific platform:
Continua”Find CPU Hogs on a Redhat machine”

Our db manager wanted to know the current patch level on our Solaris system
Here’s the commands.

#showrev -p
or
#patchadd -p

Recommend you use showrev -p since it’s a binary program. The patchadd utility is a script; therefore, it takes awhile to run.

To check the Solaris version cat /etc/release

—————————————————————————-

List all services on at run level 1:

# chkconfig –list | grep 1:on

—————————————————————————-

Enable a service:

# chkconfig cups on

—————————————————————————-
Continua”Managing Init Scripts with chkconfig”

why awk?

awk is small, fast, and simple, unlike, say, perl. awk also has a
clean comprehensible C-like input language, unlike, say, perl. And
while it can’t do everything you can do in perl, it can do most things
that are actually text processing, and it’s much easier to work with.

Continua”Simple Awk Tutorial”

These are really great tips. I have used many of these tips during my time working as a systems administrator and they always come in handy.

Found here

The best systems administrators are set apart by their efficiency.
And if an efficient
systems administrator can do a task in 10 minutes that would take another
mortal two hours to complete, then the efficient systems administrator
should be rewarded (paid more) because the company is saving time, and
time is money, right?
Continua”IBM’s Lazy Linux Administrator Tips”

This was very useful to me troubleshooting some nfs issues. I figured i post it here in case someone is having issues with NFS.

Careful analysis of your environment, both from the client and from the server
point of view, is the first step necessary for optimal NFS performance. The
first sections will address issues that are generally important to the client.
Later (Section 5.3 and beyond), server side issues will be discussed. In both
cases, these issues will not be limited exclusively to one side or the other,
but it is useful to separate the two in order to get a clearer picture of
cause and effect.

Continua”Optimizing NFS performance”

found here

DJG’s Sudo Guide

Created on January 1st, 2000.

sudo is a package which will allow priveleged users to run commands as other
users. This is sort of like assigning users to different groups to give them
special permissions to files. However, this can allow users acccess to
specific commands on specific machines, making it a more effective and more
organized way of giving special priveleges to users.

First, you’ll have to get the sudo package.
Continua”Configure the Sudo Command”

Found at http://www.grymoire.com/Unix/Sed.html

Thanks for making this the number #1 page in Google on ’sed’!

Sed - An Introduction and Tutorial

Bruce Barnett

Last update: Sun Jul 20 21:59:55 EDT 2008

Thanks to Keelan Evans, Fredrik Nilsson, and Kurt McKee for spotting some typos.

Thanks to Wim Stolker and Jose’ Sebrosa as well.

Thanks to Olivier Mengue.

Thanks to Andrew M. Goth.

Thanks to David P. Brown.

Thanks to Axel Schulze for some corrections

A big thanks for Fazl Rahman for spotting dozens of errors.

Table of Contents

Continua”Sed Introduction and a nice tutorial”