Proxy server is a computer system or application which is installed on computer system that works as a  acts as an agent or channel for requests from clients looking for resources from other servers. You can check see this post for more information about installation and configuration of Squid Proxy.

Now after installation when you try to check your IP in any site like whatismyip.com it will show that you are using proxy along with the hostname and version of Squid proxy server which is a security concern.

1) Hide Proxy version & server hostname

a) Hide Squid Version

open “/etc/squid/squid.conf” in a editor like vim and search for “httpd_suppress_version_string” and enable it.

Change FROM:

TO:

b) Hide Hostname

Search for “visible_hostname” and change FROM:

TO:

<your desired hostname> will be the name you want to show to world

2) Configure Multiple IP for Squid

Sometime it happens that the Proxy server which you have setup have multiple IP address and you want to configure squid server to use multiple IP addresses (i.e. Systems will show the secondary IP of the server instead of primary). Open squid configuration file; search for “tcp_outgoing_address” and add following

Replace <IP Address> with the IP assigned to your Proxy Server.

Restart Squid Server with command “service squid restart“

Last week I have installed “Macbuntu” on my Ubuntu 10.04 system which looks fabulous but it was putting extra burden on Resource of my system. So, I un-installed it and after reboot it was just like fresh installed system i.e. all my customized settings, desktop, wallpapers were switched back to default settings.

After 20-30 minutes I was able to customized the system as per my requirements but still there were two things which we not acting as per my previous settings which were

1) Terminal was not showing Desktop wallpaper as background (instead if I make it transparent it just transparent the screen which shows applications behind it). Just like below image

2) ALT+TAB which is used to switch between the applications was really very show and it was showing a preview of every application (which is consuming more resources and making it slow).

I have searched on forums and found that Gnome’s “Compositing manager (compiz)” is enabled on the system. Compositing manager is a component which is used to enhance the GUI (Graphical User Interface). You can disable it through command line or through Gnome Editor.

For Command Line execute following command on terminal of your system.

For Graphical User

Press Alt-F2 to open the Run Application dialog (like below image). Type gconf-editor and press enter.

Navigate to apps >> metacity >> general and uncheck the compositing_manager option.

Thats it and everything seems working properly again. I can see the desktop image on terminal as well as ALT+TAB is giving fast results.

Atmail webmail system offers a webmail client, email server platform and mailserver appliance for Linux, Unix and Windows. Plesk 9.x supports Atmail and while sending emails using Atmail every email shows following message in the footer of the email sent.

Msg sent via @Mail - http://atmail.com/

This message is quite irritating and look un-proffestional. This message can be removed by editing AtMail Configuration file which can be located at following location

Plesk Windows: C:\Inetpub\vhosts\webmail\atmail\libs\Atmail\config.php for Win
Plesk Linux: /var/www/atmail/libs/Atmail/Config.php
Normal Location: [Atmail installtion location]/libs/Atmail/Config.php

Search for ‘footer_msg’ option and change the message you want to set OR keep it blank

FROM:
'footer_msg' => 'Msg sent via @Mail - http://atmail.com/',

TO:
'footer_msg' => 'YOUR COMPANY NAME OR ANY TEXT',
OR
'footer_msg' => '',

Restart the webserver.

Problem:
If you are using MySQL Server version 4.x.x on your server but when you try to access PHPMyAdmin from Cpanel you will get following Error:

Due to your application configuration or any other reason you want to access PHPMyAdmin without upgrading MySQL version to 5.x.

Solution:
To fix this issue you should have root level access to your Server (if you are on shared server please contact your hosting company).

1) Login to server (SSH) using root login credentials.
2) Remove “_usr_bin_mysql_config_–version” file using following command

3) Now update your PHPMyAdmin (forcefully) with following command

Now try to access PHPMyAdmin

1) VIPCA Configuration
Error 1: error while loading shared libraries -libpthread.so.0
While installing Oracle 10gR2 RAC (Cluster) on Redhat Enterprise Linux 5 or CentOS 5 you will get following error when you execute root.sh (After Cluster Installation) on last node. This Error is thrown when root.sh execute VIPCA which Virtual IP configuration Tool.

To fix this issue edit /u01/app/oracle/product/10.2.0/clust/bin/vipca and add following (Green colored or on line number 124):

Error 2: Error 0(Native: listNetInterfaces:[3])
Once above changes made and when you run /u01/app/oracle/product/10.2.0/clust/bin/vipca you will get following Error

Now you will have to configure Virtual IP’s Manually. You can configure it using following commands

Now Run VIPCA

2) Srvctl Error:
While checking status of RAC using command srvctl you will again get the following error:

To fix this bug edit following files

and add following (Green colored):

Now Execute srvctl commands to check the current configuration and status of the RAC database

While installation of any package or Starting any service on a RHEL or CentOS based Server you may receive following Error

This Error comes when SELinux setting is enabled on the server. Security-Enhanced Linux (SELinux) is a Linux feature that provides a mechanism for supporting access control security policies through the use of Linux Security Modules (LSM) in the Linux kernel.

By Default SELinux is set to “enforcing” in CentOS on boot, this can be disabled permanently. To disable it edit file “/etc/selinux/config” and change SELINUX

From

TO

But to apply this setting the System or Server need to be rebooted. If you want to disable this feature temporary you can execute following command from the Shell of the System or Server

_

While setting and configuring NFS share on a server when you try to restart portmap service you get following error

Logs (tail -f /var/log/message) shows that portmap port is conflicting with some other service.

I have searched on internet and found following commands which fixed the issue.

1) Stop portsentry service

2) Restart portmap service

3) Start portsentry service

Try to configure NFS now :)

_

Setting time on a Virtual Machine is always a painful tasks. Different virtualization platform have different techniques of setting time like in Virtuozzo you can change the Timezone of the VM but you can’t set time as it synchronize the time from the host server.

On a Citrix Xen VM also the clocks synchronized to the time running on the host server, and cannot be independently changed. So, when you try to set time (using date -s command) on a Xen VM it will show that the command is executed but it won’t change the time. You can see that in following

To change the time on a VM you need to enable independent clock settings of the VM which is disabled by default which you can see using following command.

Output of the above command is “0″ which shows that independent clock settings for the VM is disabled. Now use following command to enable it

and verify if its enabled or not

Now try to set the date and time using date –set or date -s command.

After installation OR while updating ClamAV Antivirus (using command /usr/local/bin/freshclam -v) it gives following Error

[root@server ~]# /usr/local/bin/freshclam -v -l /var/log/clam-update.log
ERROR: Please edit the example config file /usr/local/etc/freshclam.conf
ERROR: Can't open/parse the config file /usr/local/etc/freshclam.conf
[root@server ~]#

This error shows that the ClamAV configuration file still the default one which is bundled with the the installation Sources. To fix this error open /usr/local/etc/freshclam.conf and search and change

FROM:
# Comment or remove the line below.
Example

TO:
# Comment or remove the line below.
#Example

Now try to update ClamAV

[root@server ~]# /usr/local/bin/freshclam -v -l /var/log/clam-update.log
Current working dir is /usr/local/share/clamav
Max retries == 3
ClamAV update process started at Fri Oct  9 11:29:18 2009
Using IPv6 aware code
Querying current.cvd.clamav.net
TTL: 748
Software version from DNS: 0.95.2
main.cvd version from DNS: 51
main.cvd is up to date (version: 51, sigs: 545035, f-level: 42, builder: sven)
daily.cvd version from DNS: 9876
daily.cvd is up to date (version: 9876, sigs: 83897, f-level: 43, builder: ccordes)
[root@server ~]#

/usr/local/bin/freshclam -v -l /var/log/clam-update.log

Recently working on a Debian server, which was not responding to SSH connection. I have checked and found that the SSH service was down and while restarting it it gives following error

sh-3.1# /etc/init.d/ssh restart
PRNG is not seeded
sh-3.1#

I have searched on Google and found that the problem occurs when /dev/random and /dev/urandom are missing from the server.

sh-3.1# ls -al /dev/random
/bin/ls: /dev/random: No such file or directory
sh-3.1# ls -al /dev/urandom
/bin/ls: /dev/urandom: No such file or directory

As it was a VPS I directly logged into it from the host server but in case of Dedicated/Physical Server you will have to use console. Once you logged into the server execute following commands to create /dev/random and /dev/urandom

sh-3.1# mknod /dev/random c 1 9
sh-3.1# mknod /dev/urandom c 1 9