POLL RESULTS: Do you use a firewall on dedicated Linux / BSD box?

Posted on in Categories Poll last updated November 24, 2007

In last months reader poll I asked about Firewall on dedicated UNIX / Linux box.

Poll Result: Do you use a firewall on dedicated Linux / BSD box?

Do we really need a firewall?

Personally, I install firewall on all boxes to filter out unwanted junk and IPs; even if box is only running public service such as a web server. The overall idea is to limit access and reduce liability on my part if serer got rooted (read as compromised). Remember, bad boys never play by the rules.

nixCraft FAQ Roundup May 14, 2007

Posted on in Categories FAQ last updated May 14, 2007

Recently updated/posted Linux and UNIX FAQ (mostly useful to Linux/UNIX new administrators or users) :

Enjoy!

Linux/UNIX: Sharing A CUPS Printer Queue

Posted on in Categories Linux, Networking, UNIX, Windows last updated June 23, 2006

Common Unix Printing System (CUPS) is a modular computer printing system for Apple OS X, Linux and UNIX like operating systems. It allows Linux computer to act as a printer server. As a server it accepts printing requests from all client computer and send them to actual printer. It does printing accounting and other important stuff.

Testing Oracle 10g installation on Red Hat Linux AS 4.0

Posted on in Categories Howto, Linux last updated February 22, 2006

One of my friend installed Oracle first time. After installation, he just wants to make sure everything is working fine so he called me. If you are installing oracle for Unix/Linux oses first time then it will confuse you. He wanted to know how to start oracle service and test it. He emailed me the following error:
ORA-27101: shared memory realm does not exist
ORA-01034: ORACLE not available

You need to add following line to oracle user’s .bash_profile file for testing purpose (once it is tested, you can give control to Oracle DBA) (login as a oracle user):
$ cd;vi .bash_profile
Append following lines:
export ORACLE_HOME=/home/oracle/oracle/product/10.2.0/db_1
export ORACLE_SID=orcl
export PATH=$PATH:$ORACLE_HOME/bin

Save file. Just load the above settings:
$ . .bash_profile
Start oracle Net listing service:
$ lsnrctl start
ALTERNATIVELY use full path:
$ /home/oracle/oracle/product/10.2.0/db_1/bin/lsnrctl start
Start oracle database:
$ dbstart
ALTERNATIVELY, use full path:
$ /home/oracle/oracle/product/10.2.0/db_1/bin/dbstart
Connect to Oracle database with sqlplus client (test it with scott username):
$ sqlplus "scott/tiger"
sql> select * from tab;

To shutdown Oracle database:
$ lsnrctl stop
$ dbshut

Further readings:

If you are new to Oracle try out Oracle Database 10g Documentation library, especially 2 Day DBA is fantastic document. Do not forget check out John Smiley’s “Installing Oracle Database 10g Release 2 on Linux x86” article. It will teach you the basics of installing Oracle Database 10g Release 2 on Red Hat Enterprise Linux or Novell SUSE Enterprise Linux, from the bare metal up.

Read UNIX / Linux System IP Address In a Shell Script

Posted on in Categories Linux, Shell scripting last updated January 16, 2006

Reading an IP address in shell script required many time. However, different Linux distribution stores IP address in different files. If you are looking to run script under different UNIX like OSes such as Solaris or FreeBSD then you need to use the ifconfig command. The ifconfig command is not just used to configure a network interface, but it can be use to obtained information such as network IP, netmask and much more.