System Administration

System Administration - Tips, Guidelines, HowTo's

How to add multiple IPs to a single ethernet card in CentOS from CLI

When you you wish to run multiple services bound to different IPs possibly under different subnets from a single machine the simple way is to create multiple virtual adapters tied to a single physical card. The following instructions are for CentOS but should also work for RedHat and Fedora.

Fixed: Ubuntu Startup slows down at Starting Mail Transport Agent (MTA) sendmail

If you install sendmail on your desktop and have not configured your system correctly you will very likely come across this problem. Ubuntu boot up slows down considerably and stops for a long time at the "Starting Mail Transport Agent (MTA) sendmail" line. This is because sendmail is trying to resolve your host and times out failing to do so. You can fix this problem easily by making a few changes in to yours hosts file.

How much web hosting space and bandwidth do you really need for your website?

One of our commitments to our customers is that we will never force our products/service on you just for the sake of selling these. We try our best to match your requirement with the products and services we offer and fit the one that best fits your needs. We have been selling our hosting services both in the local market and in the international market for the last 2 years and we have been slowly building a set of loyal customers for these services. One of the frequent questions that we have had to answer was "How much web space and bandwidth do you really need for a website". This is a tough question to answer without really knowing what you are going to put up on the site and how many are going to visit it. In any case here are the general tips and guidelines that we offer our customers.

Solution to checksum error and md5 sum error in Brasero, K3B and other burning software

If you happen to be one of those people who burn lot of iso's like we do through our RequestCD program then you would most probably have come across the dreaded checksum errors or md5sum errors. We used to get a lot of these and interestingly we found that we get consistent md5 checksum errors with certain iso images. We were almost sure that this had nothing to do with actual burning errors since they happened only for certain iso images. After hours of scouring the internet we found out the real culprit behind these errors and a way to really work around these phony error messages and actually verify if the iso was written correctly. We burn using either Brasero or K3B but this information can be applied to other cd/dvd burning software as well.

Fix corrupted iso images with invalid md5 checksum using Bittorrent

We have been running the RequestCD Program for more than a year now. For this program we have been heavily downloading iso's, mostly GNU/Linux distributions. We download either through direct downloads or through bittorrent. Bittorrent downloads are inherently safer because the downloaded iso would be guaranteed error free. However http and ftp downloads results in corrupted downloads once in a while. Traditionally when you end up with a corrupted iso you had to download the iso file again. Not anymore. You can easily repair a corrupted iso using Bittorrent.

Solution to 'malformed macro definition' and 'DEBCONFsomethingDEBCONF found in exim configuration'

Upgrading a working server application is always tricky. This is especially true if the upgrade had changes in configuration files and you had customizations done in your local configuration file. The recent exim4 upgrade to version 4.67-3 had structural changes in the configuration files. The suggested upgrade method is to accept all the modifications provided by the upgrade and redo the customizations. But what if you did not read the instructions properly and ended having an exim4 installation that throws out errors every time you try to start exim4.

Stop your DNS Servers from changing after every reboot while using DHCP

Do you find your custom DNS server entries being deleted after every reboot or after every disconnection? Do you use DHCP but still want to use your own DNS servers? Do you want to use OpenDNS and ignore the DNS servers provided by your ISP? Well here is how you can do this on Ubuntu. This solution applies to Ubuntu but might very well work for other distributions of GNU Linux as well.

How to create and extract a .tar.gz archive using command line

One of the most common compression formats used in GNU/Linux and variants is tar.gz. A tar.gz file is nothing but a gzipped tar archive. These days users of GNU/Linux system seldom have to use the command line to create or extract tar.gz archives. But it is a useful command to keep in your arsenal if you are a system administrator.

Migrating Local Mail Server to Google Apps

We had a query from one of our customers to help them migrate their local mail server to Google Apps. They wanted to do this because they did not have the sufficient in-house capability nor have the funds to get paid external capability to support an internal mail server. One hurdle that they were facing was that they had around 40GB of mail left on the local mail server that they wanted to migrate to the new mail accounts they created on Google Apps.

Installing Linux Mint on 256MB RAM without an alternative install CD (text based)

We recently had to install GNU/Linux on 40 computers at the regional Police Training College(PTC), Trivandrum. This was part of a Free Software Training Program that PTC is conducting currently for police personnel in Kerala. Zyxware was proudly part of this initiative both in training and in setting up GNU/Linux GNU/Linux on all 40 computers in the training lab. We had also prepared Linux Mint cds to be given to the trainees given their non-technical backgrounds.
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