Linux Servers cPanel webhosting blog » Linux Administrator Interview Questions

Server wide permission issue after enabling suphp

Gunjan — Sun, 22 Jan 2012 09:24:01 +0000

After enabling the suphp on the server,many time 500 Internal Server Error occur due to the incorrect permission,ownership and incorrect php module defined in the .htaccess file and we can’t make the changes manually therefore we can use the following script to make the all the changes server.

linux7802@server[~]#cat /root/suphppermission.sh

#!/bin/bash

# Reset the directory permissions.
chmod 755 /opt/suphp
find /opt/suphp -type d -exec chmod 755 {} \;

# Reset permission,ownership for cPanel user
for user in `/bin/ls /var/cpanel/users`; do

chown -R ${user}:${user} /home/${user}/public_html
chmod 755 /home/${user}/public_html
find /home/${user}/public_html -type f -exec chmod 644 {} \;
find /home/${user}/public_html -type d -exec chmod 755 {} \;

# Remove php_values in the .htaccess file.
find /home/${user}/public_html -name ‘.htaccess’ -exec sed -ie ‘s/php_value/#php_value/’ {} \;
find /home/${user}/public_html -name ‘.htaccess’ -exec sed -ie ‘s/php_flag/#php_flag/’ {} \;
done

If you have any issue to copy the above content the download the script from following URL
scr

cPanel log to check when hosting created and deleted

Gunjan — Wed, 11 Jan 2012 13:28:55 +0000

In the recent days, we all are facing the hacking issue at that time, we always see problem like account termination from the serve at that time, we can use the following log file to investigate the issue as its providing when hosting account was created, owner changed or account deleted from the server.

For example we are checking logs for the domain test123.com and as per the following logs the hosting account for domain test123.com is created by using the root owner on dated Wed Jan 11 08:19:40 2012 and onwership is under root

root@linux7802 [~]# cat /var/cpanel/accounting.log | grep test123.com
Wed Jan 11 08:19:40 2012:CREATE:root:root:test123.com:115.124.103.126:admin111

Now we have changed the ownership for the domain test123.com hosting account to linux780 reseller ownership therefore check the following logs

root@linux7802 [~]# cat /var/cpanel/accounting.log | grep test123.com
Wed Jan 11 08:22:51 2012:CHANGEOWNER:root:root:test123.com:admin111:root:linux780

Now we have terminated the hosting account for the domain test123.com by using the root user and its also recorded in the accounting.log

root@linux7802 [~]# cat /var/cpanel/accounting.log | grep test123.com
Wed Jan 11 08:25:14 2012:REMOVE:root:root:test123.com:admin111

So we can similarly check the logs for all the domains when they have created/modified or removed from the server and its always to better to maintain the accounting.log for future reference.

vzmigrate command for VPS migration

Gunjan — Tue, 10 Jan 2012 14:40:56 +0000

The vzmigrate command is used to migrate the one VPS from node to the new or another node.

For example, we want to migrate the VPS which is currently having id 110 on new node and its ip is 192.168.0.1

server@linux[~]# vzmigrate 192.168.0.1 110

server@linux[~]# vzmigrate -r no 192.168.0.1 110

Some time node on which,we are trying to migrate the VPS we are receiving the following error message

110 already exists on the destination node.

To resolve the above error we can assign new id to the VPS

server@linux[~]#vzmigrate -r no 192.168.0.1 110:120

The new id on the new node will be 120 for VPS

We can also do online migration of VPS from one to another node.

server@linux[~]#vzmigrate --online 192.168.0.1 110

or

server@linux[~]#vzmigrate --online 192.168.1.130 110:120

If you want to migrate all the running VPS from one node to another node then refer to following command

for CT in $(vzlist -H -o veid);

do vzmigrate --remove-area no --keep-dst $1 $CT; done

cPanel file manager giving 404 not found error

Gunjan — Sun, 08 Jan 2012 16:28:00 +0000

While browsing the file manager from the cPanel the 404 not found error message is occur.

Not Found

The server was not able to find the document (./frontend/x3/index.html) you requested.
Please check the url and try again. You might also want to report this
error to your web hosting provider.

whostmgrd/11.25

As per above error message x3 theme is causing the problem therefore simply move the x3 theme and resinstall it by running the upcp, you can rename the theme under which you are facing the problem.

linux@server[~]#cd /usr/local/cpanel/base/frontend

linux@server[~]#mv -v x3 x3-corrupt

linux@server[~]#/scripts/upcp –force

Now browse the file manager, it will work properly.

How to block referrer from single domain and multiple domains

Gunjan — Sun, 08 Jan 2012 00:59:46 +0000

Use the following rewrite rule to block the referrer from single domain/web site.

RewriteEngine on
# Options +FollowSymlinks
RewriteCond %{HTTP_REFERER} test\.com [NC]
RewriteRule .* – [F]

Similarly you can block the referrer from the multiple sites by using the following rewrite rule in the .htaccess file.

RewriteEngine on
# Options +FollowSymlinks
RewriteCond %{HTTP_REFERER} test\.com [NC,OR]
RewriteCond %{HTTP_REFERER} test123\.com
RewriteRule .* – [F]

Mysql tuner to tune mysql service

Gunjan — Wed, 28 Dec 2011 05:42:46 +0000

Install the mysql tuner to tune the mysql service to avoid any memory usage due to incorrect settings in the /etc/my.cnf file.

root@linux7802 [~]# cd /usr/local/src/

root@linux7802 [/usr/local/src]# wget -O mysqltuner.pl mysqltuner.pl

root@linux7802 [/usr/local/src]# perl mysqltuner.pl

Above command will give you the statistics as well as recommendations to improve the server perfomance

Refer to the following image to example of statistics

For recommendations example refer to the following image and made the necessary changes in the /etc/my.cnf file and retest the script to check, if issue resolved or not……

Its an example for recommendations

Note : Most of the time it recommend to optimize the mysql at that time use the following command but make sure that you have talen backup for the /var/lib/mysql directory to avoid any problem.

mysqlcheck –optimize -A

Install and upgrade the rsync

Gunjan — Mon, 26 Dec 2011 05:45:32 +0000

To increase the download speed via rsync its always better to use the latest rsync version.Refer to the following steps to install and upgrade the rsync

Loghin in to the server as a root user

root@linux7802 [~]# cd /usr/src/

Now download the latest rsync version source from the url https://rsync.samba.org/ftp/rsync/src/

root@linux7802 [/usr/src]#wget https://rsync.samba.org/ftp/rsync/src/rsync-3.0.9.tar.gz

root@linux7802 [/usr/src]#tar -xzvf rsync-3.0.9.tar.gz

root@linux7802 [/usr/src]#cd rsync-3.0.9/

root@linux7802 [/usr/src/rsync-3.0.9]# ./configure

root@linux7802 [/usr/src/rsync-3.0.9]# make

root@linux7802 [/usr/src/rsync-3.0.9]# make test

root@linux7802 [/usr/src/rsync-3.0.9]# make install

root@linux7802 [/usr/src/rsync-3.0.9]# rm -f /usr/bin/rsync

root@linux7802 [/usr/src/rsync-3.0.9]# ln -s /usr/local/bin/rsync /usr/bin/rsync

Now check the new rsync version

root@linux7802 [/usr/src/rsync-3.0.9]# rsync –version
rsync version 3.0.9 protocol version 30

Its 3.0.9 now

Enable mod gzip and mod deflate module

Gunjan — Sat, 24 Dec 2011 05:51:34 +0000

The server load is normal but web pages are loading very slow due to heavy web size therefore at that time, we can enable the web page compression for the hosting account. To enable the compress make sure that mod_deflate module.

To install the mod_deflate module refer the following setps.

root@linux7802 [~]# /scripts/easyapache

Select the “Deflate” option available under the “Apache Built-in Modules” as soon as Apache recompiled login in to domain hosting account under which you are facing the problem.

For example the linux7802.com domain having the slow web page loading issue therefore we can create the new .htaccess file or edit the existing .htaccess file and add the following code.

#compress all text & html:
AddOutputFilterByType DEFLATE text/html text/plain text/xml
# Or, compress certain file types by extension:

SetOutputFilter DEFLATE

Check the following file

root@linux7802 [/home/linux780/public_html]# cat .htaccess
#compress all text & html:
AddOutputFilterByType DEFLATE text/html text/plain text/xml
# Or, compress certain file types by extension:

SetOutputFilter DEFLATE

We can also use the following code in the .htaccess file

#compress all text & html:
AddOutputFilterByType DEFLATE text/html text/plain text/xml
# Or, compress certain file types by extension:

SetOutputFilter DEFLATE

After adding the above check the web page compression by using the following URL

http://www.gidnetwork.com/tools/gzip-test.php

Update the webalizer logs manually

Gunjan — Tue, 13 Dec 2011 10:22:19 +0000

To update the webalizer for the single domain refer the following steps, for your kind information if domlogs are rotated on the server then it could be possible that you will miss the existing stats therefore run the command after taking all the essential files backups.

root@server [~]#/usr/local/cpanel/3rdparty/bin/webalizer /usr/local/apache/domlogs/DomainName -n DomainName

For example we are runnning the webalizer for the theperfectarts.com domain

root@server [~]#/usr/local/cpanel/3rdparty/bin/webalizer /usr/local/apache/domlogs/theperfectarts.com -n theperfectarts.com

Once above command run successfuly run the following command

root@server [~]#/usr/local/cpanel/startup

Set alternative SMTP port in Plesk Linux server

Gunjan — Sat, 10 Dec 2011 10:19:00 +0000

Some time local ISP blocked default SMTP port 25 in the local network therefore we have to configure the alternative smtp port for SMTP service, so that SMTP will work on default port 25 as well as other new port. For example we are configuring the SMTP service on port 2626. Refer to the following steps to configure SMTP service on another port.

Change directory to the /etc/xinetd.d

root@server [~]#cd /etc/xinetd.d

Now copy the current working smtp_psa file to the new file smtp_psa_new

root@server [/etc/xinetd.d]#cp -p smtp_psa smtp_psa_new

open the file smtp_psa_new and change the value in the first line

From

service smtp
to
service smtp_psa_new

Save the file and add the new smpt port in the /etc/services file

For example we want to set new smtp port 2626, you can change the port as per your requirement

smtp_psa_new 2626/tcp mail
smtp_psa_new 2626/udp mail

Save the file and restart the xinetd service

root@server [/etc/xinetd.d]#/etc/init.d/xinetd restart

Make sure that you have opened new port in the server firewall and then try to telenet the new SMTP port

root@server [/etc/xinetd.d]#telnet localhost 2626

It will show you the SMTP service banner