Parallels Virtuozzo Technology which is used to create Virtual Environments or Containers for both Windows and Linux Based Servers. Each Virtual Environments has it’s own CPU, RAM and Disk Space in which OS is installed. Virtuozzo for Windows allows user to use VE Disks of Two types; they are

1) Plain :
This is a default Disk type for VE’s in Virtuozzo. In this type at the time of VE creation all nominal disk size is being allocated or assigned to the VE’s at once. For Example, if you have assigned Disk Space of 100 GB; 100 GB out of available Disk Space will be assigned to the VE. The biggest disadvantage Plain Disk Type is it consumes heavy disk space of Host server even if the VE is not using that much of Disk.

2) Compact:
This Disk Type was introduced with Virtuozzo Update VZU35159 for Virtuozzo 3.5.1 and VZU40006 for Virtuozzo 4.0. Here, disk file of the VE starts small at the time of creation and it becomes larger as soon as user add’s more data. Every newly created VE (without OS) comes with default Disk quota of 17 MBs and goes increasing as more data get added. Compact disks experience slight performance degradation compared to plain disks, but allow to save considerable amount of disk space.

Creating VE with Disk Type.
User can assign Disk Type at the time of VE creation. Following are the commands for the same:

For plain disks:
vzctl create 101 –pkgset w2k3 –disktype plain

For compact disks:
vzctl create 101 –pkgset w2k3 –disktype compact

Setting the VE Disk Type

Disk Type of a VE can be set or changes at any moment during the VE life-cycle by entering following commands from command prompt:

For plain disks:
vzctl set 101 –disktype plain

For compact disks:
vzctl set 101 –disktype compact

Converting Disk Type will include downtime for a VE as it takes sometime for conversion which depends upon total Disk Usage of the VE

Querying Disk Type of the VE

Following is the command to see the Current Disk Type of the VE

After login into a VPS using RDP it stuck on Blue screen (Not BSOD) and doesn’t load next screen or Desktop of the VPS like below given image

OR if you get following Error after login to VE by RDP

“You are connected to the remote computer. However, an error occurred while an initial user program was starting, so you are being logged off. Contact the system administrator for assistance.“

Such problems occurs due to corrupted or missed C:/Windows/explorer.exe of the VPS or VE.

This problem can be fixed by copying C:/Windows/explorer.exe file of the host server to the VPS. Following are the steps to copy

1) Stop the VPS
#       vzctl stop VEID

2) Mount the VPS
#      vzctl mount VEID

Now we will able to access VPS files from host server in C:/vz/private/VEID/ Directory.

3) Copy “C:/Windows/explorer.exe” from Host server to “C:/vz/private/VEID/Windows/explorer.exe“

4) Unmount and start the VPS
#      vzctl umount VEID
#      vzctl start VEID

Please try to login to the VPS now.

Note: Here, VEID will be the VPS ID of the VE which is facing problem.

First of all, Happy New Year to all the reader as This is the Very First Post for this Year.

Enabling IPTables Modules

Today I will going to explain How to install and configure CSF on a VPS. As VPS is a Virtual Server which shares the resources from the Host server including Kernel Modules, before installation of any firewall on Linux VPS make sure to have some required modules enabled on the host server. Following is the List of modules which required on the host server.

ipt_MASQUERADE
ipt_helper
ipt_SAME
ipt_REDIRECT
ipt_state
ipt_TCPMSS
ipt_LOG
ipt_TOS
tun
iptable_nat
ipt_length
ipt_tcpmss
iptable_mangle
ipt_limit
ipt_tos
iptable_filter
ipt_helper
ipt_tos
ipt_ttl
ipt_REJECT

You can check the modules which are loaded on Host Server using command “lsmod” and if you get following for x_tables the you have all the modules configured otherwise you can enable them using “modprobe” command

x_tables               19204  21 iptable_nat,xt_limit,xt_multiport,ipt_tos,ipt_TOS,ipt_REJECT,ipt_TCPMSS,xt_tcpmss,ipt_ttl,ipt_LOG,xt_length,xt_conntrack,xt_state,xt_helper,ipt_REDIRECT,ipt_recent,ipt_owner,ip_tables,ip6t_REJECT,xt_tcpudp,ip6_tables

You can copy and paste the following commands to enable all the required IPTables modules

modprobe ipt_MASQUERADE
modprobe ipt_helper
modprobe ipt_SAME
modprobe ipt_REDIRECT
modprobe ipt_state
modprobe ipt_TCPMSS
modprobe ipt_LOG
modprobe ipt_TOS
modprobe tun
modprobe iptable_nat
modprobe ipt_length
modprobe ipt_tcpmss
modprobe iptable_mangle
modprobe ipt_limit
modprobe ipt_tos
modprobe iptable_filter
modprobe ipt_helper
modprobe ipt_tos
modprobe ipt_ttl
modprobe ipt_REJECT

Enable Firewall Modules for VPS

Once the IPtables modules are enabled on Host server, execute following command from the shell (of HW Node) to enable modules for the VPS.

vzctl set VEID --iptables ipt_REJECT --iptables ipt_tos --iptables ipt_TOS --iptables ipt_LOG --iptables ip_conntrack --iptables ipt_limit --iptables ipt_multiport --iptables iptable_filter --iptables iptable_mangle --iptables ipt_TCPMSS --iptables ipt_tcpmss --iptables ipt_ttl --iptables ipt_length --iptables ipt_state --iptables iptable_nat --iptables ip_nat_ftp --save

Or you can open VPS Configuration file i.e. /etc/vz/conf/VEID.conf and paste following in the last line of the file

IPTABLES="iptable_filter iptable_mangle ipt_limit ipt_multiport ipt_tos ipt_TOS ipt_REJECT ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_LOG ipt_length ip_conntrack ip_conntrack_ftp ip_conntrack_irc ipt_conntrack ipt_state ipt_helper iptable_nat ip_nat_ftp ip_nat_irc"

Here, VEID is the VPS ID of the Server

In Next Part, I will tell how to install and configure CSF on different Control Panels. You can check the Next Part here

Default firewall for Linux i.e. iptables is depends upon many kernel modules without which a server can’t be secured properly. Also the firewall configurations will give many errors while configuring it. So, it is required to have proper kernel modules enabled for a Server.

In case of a VPS, Virtually Hosted server which shared resources and kernel of Host server it’s not possible to compile/enable kernel related modules for a VPS from it. So, to run iptables properly a VPS too have proper kernel modules enabled which can be enabled from the host server. Normally a Virtuozzo OR OpenVZ based kernel only support following iptables modules

ipt_MASQUERADE
ipt_helper
ipt_SAME
ipt_REDIRECT
ipt_state
ipt_TCPMSS
ipt_LOG
ipt_TOS
iptable_nat
ipt_length
ipt_tcpmss
iptable_mangle
ipt_limit
ipt_tos
iptable_filter
ipt_helper
ipt_tos
ipt_ttl
ipt_REJECT

ENABLE MODULES ON HOST SERVER

To enable these modules for a VPS you will first have to enable these modules on the host server using command modprobe . So, just copy and paste the following commands on the Shell of HOST SERVER

modprobe ipt_MASQUERADE
modprobe ipt_helper
modprobe ipt_SAME
modprobe ipt_REDIRECT
modprobe ipt_state
modprobe ipt_TCPMSS
modprobe ipt_LOG
modprobe ipt_TOS
modprobe iptable_nat
modprobe ipt_length
modprobe ipt_tcpmss
modprobe iptable_mangle
modprobe ipt_limit
modprobe ipt_tos
modprobe iptable_filter
modprobe ipt_helper
modprobe ipt_tos
modprobe ipt_ttl
modprobe ipt_REJECT

Now make sure that all these modules are enabled on the server using command “lsmod“.

ENABLE MODULES FOR VPS

Now the above mentioned modules can be enabled for a VPS using two ways i.e. by using command OR by adding rules manually.

1) By Command:

Execute following command from the host server to enable all the modules for the VPS

vzctl set VEID --iptables ipt_REJECT --iptables ipt_tos --iptables ipt_TOS --iptables ipt_LOG --iptables ip_conntrack --iptables ipt_limit --iptables ipt_multiport --iptables iptable_filter --iptables iptable_mangle --iptables ipt_TCPMSS --iptables ipt_tcpmss --iptables ipt_ttl --iptables ipt_length --iptables ipt_state --iptables iptable_nat --iptables ip_nat_ftp --save

2) Adding Rules manually:

Open the VPS configuration file which exists at /etc/vz/conf/veid.conf and paste following in the last line of the file.

IPTABLES="iptable_filter iptable_mangle ipt_limit ipt_multiport ipt_tos ipt_TOS ipt_REJECT ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_LOG ipt_length ip_conntrack ip_conntrack_ftp ip_conntrack_irc ipt_conntrack ipt_state ipt_helper iptable_nat ip_nat_ftp ip_nat_irc"

After adding rules reboot the VPS to apply/enable the modules.

After installation of Atmail Webmail Client, while restarting Apache it throws following Syntax Error:

First we will have to check where atmail is installed. We can do that by querying the RPM files using option “rpm -ql“

The above output shows that the files are created in “/etc/psa-webmail/” directory instead of “/etc/psa/webmail/“

So, copy the file to relevant directory as in the conf file of httpd service

After that we were able to start the httpd service successfully.

Sometime when you have enabled many YUM Repositories like local repository, rpmforge, ATrpms for your server and it’s quite difficult to manage packages where you want that the package which you want to install too be searched on Local Repository first, then to CentOS Base, update and if it doens’t find the package here it will go for any other Third Party Repositories.

This Task can be done by setting up Priority for the Yum Repositories. Following are the steps to set Priorities for YUM Repositories

1) Install yum-priorities

The yum-priorities is used to enforce ordered protection of repositories, by giving priorities to repositories. Packages from repositories with a lower priority will never be used to upgrade packages that were installed from a repository with a higher priority. The priorities are also in effect when a new package is installed – if a package is in more than one repository, it will be installed from the repository with the highest priority. This plugin is particularly useful for anyone who uses one or more third-party repositories, as these repositories may update system files, which can potentially compromise the stability of your CentOS installation. This Package can be installed using following YUM Command.

**using option -y with yum will allow yum to install package with taking permission from user.

2) Applying Priorities

Priorities for a Repository need to be added in .repo file. Following is the syntax for setting Priority

Here [NUM] will be the Priority. The Repository with higher priority will be used for installing any package. e.g. if you want your local repository should have highest priority than you can set highest priority for the same like below

All other repositories will have lesser value as compared to Local Repository.

Sometime Schedule tasks on Microsoft doesn’t run and which checking them from Schedule tasks it give a pop up with following Error

ERROR: General page initialization failed. The specific error is: 0x8007000d: The data is invalid. An error has occurred attempting to retrieve task account information. You may continue editing the task object, but will be unable to change task account information.

Following are the steps to fix this problem/Error

1. Delete the offending “SYSTEM” account tasks in Task Scheduler.

2. Stop the Task Scheduler Service.

3. Delete all files in C:/Documents and Settings/All Users/Application Data/Microsoft/Crypto/RSA/S-1-5-18

4. Restart the service (I’d restart the system).

Recently while restarting DNS service on Cpanel VPS it shows following errors:

[root@support ~]# /etc/init.d/named start
Starting named: /usr/sbin/named: error while loading shared libraries: libdns.so.22: cannot open shared object file: No such file or directory
[FAILED]

[root@support ~]# /etc/init.d/named start
Starting named: /usr/sbin/named: error while loading shared libraries: libisc.so.11: cannot open shared object file: No such file or directory
[FAILED]

We have checked and found that the OS template [CentOS 5.3] has been update to [CentOS 5.4] due to will all the binaries of the VPS has been updated as well. For temporary work around I have copied the libdns.so and libisc.so to libdns.so.22 and libisc.so.11.

[root@support ~]# cd /usr/lib
[root@support lib]# cp libdns.so libdns.so.22
[root@support lib]# cp libisc.so libisc.so.11

After that we were able to restart named server

[root@support lib]# service named restart
Stopping named:                                            [FAILED]
Starting named:                                             [  OK  ]
[root@support lib]#

Sometime it happens that your Customers complains that they are not able to connect their Windows VPS Throug Remote Desktop Protocol i.e. RDP even if the VPS is responding ping requests. The most common reason for this is that the VPS is running out of memory, check the VPS memory using Virtuozzo Power Panel and reboot the VPS if required.

But in some VPS is running fine, domains, FTP and all the services are running fine but still RDP is not connecting; Please check the following are steps which can help to diagnosis the problem.

1) Check Terminal Services are running or not. To check that first login into the VPS using command prompt of the host server and execute command net start “terminal services” and if it show the output given below than the service is already running.

C:\>vzctl enter 99999
Microsoft Windows [Version 5.2.3790]
(C) Copyright 1985-2003 Microsoft Corp.

C:\WINDOWS\system32>net start "terminal services"
The requested service has already been started.

More help is available by typing NET HELPMSG 2182.

C:\WINDOWS\system32>

2) Check Remote Desktop Port. By default RDP use Port 3389 to connect the server/machines remotely. You can use command “netstat -aon |findstr :3389″ to see if Port 3389 is responding or not on the VPS.

C:\WINDOWS\system32>netstat -aon |findstr :3389
  TCP    0.0.0.0:3389           0.0.0.0:0              LISTENING       12308

C:\WINDOWS\system32>

If you get the above reply then the VPS is using Default RDP port (:3389) but you get following output that the RDP port has been changed by the VPS administrator

C:\WINDOWS\system32>netstat -aon |findstr :3389
C:\WINDOWS\system32>

To find the exact port you will have to execute the following commands on the command prompt of the VPS.

C:\WINDOWS\system32>tasklist /svc | find "erm"
svchost.exe                 324380 TermService
C:\WINDOWS\system32>netstat -aon | find "324380"
TCP    0.0.0.0:1050           0.0.0.0:0              LISTENING       324380

Here, RDP port has been changed from 3389 to 1050. So, try to connect the RDP using IPADDRESS:PORT

3) Check Firewall Configuration. As we have seen above that if the server is responding to port 3389 or any other port locally (inside the VPS) then there is a possibility that the firewall is blocking the access. Firewall of the VPS can be stopped using Parallel Management Console or using following commands.

C:\WINDOWS\system32>net stop sharedaccess
C:\WINDOWS\system32>net stop ipnat
C:\WINDOWS\system32>net stop policyagent

These Commands will stop the firewall service on your VPS.

4) Check for Virus/Infection. If the VPS is infected with Viruses or Trojans or any other malicious scripts then these script can also block the RDP access for the VPS. You can scan the VPS using Cureit anti-virus which is free and can be downloaded from http://www.freedrweb.com/cureit/.

NOTE: Make sure to mount the VPS (vzctl mount VEID) and then scan the private area of the VPS. If any viruses found by the Anti-virus the best option to get this issue fixed is to create a new VPS and copy the data (You can access the data of infected VPS while it’s mounted).

If everything seems to be fine then I would suggest to contact Parallels OR the Vendor from where you have purchased the License (they will contact Parallels on your behalf) for more help.

If you have installed Linux (CentOS, Fedora etc.) on your System which doesn’t have internet connections in that case it’s very difficult to install packages i.e. everytime you will have to insert OS DVD and need to install packages or even if you copy all the RPMS to local system you will have to face the dependencies problems. To fix this problem, we can create a local reposiorty of the RPMS which we have copied into the Local System. following are the steps to create a local repository

1) Copy all the RPMS from the DVD to a particular folder lets say /root/os/RPMS

2) Install createrepo RPM from /root/os/RPMS directory using rpm command

3) Now, we will have to create repo of the directory in which we have coied the RPMS. Following is the command to create the repo

[root@server ~] createrepo /root/os/RPMS

Once the above command gets completed you will find repodata directory in /root/os/RPMS folder

4) configuing YUM to work with local repository. Create a new file in /etc/yum.repo.d/ or open /etc/yum.conf and paste following

[local repo]
name = OS $release - MyLocalRepo
baseurl = file:///root/os/RPMS/
enabled=1
gpgcheck=0

Now Try to install any package using YUM