WebScHoLaR Dot NET

A blog discussing common issues of Linux, cPanel/WHM, Plesk, DirectAdmin, InterWorx

If you do a “yum update” inside Linux VPS and get this error:

Package glibc-dummy-centos-3 needs glibc-common = 2.3.2-95.30, this is not available.

Then on the VPS do

rpm –qa | grep glibc

it will list the glibc rpms installed on the VPS, look for an rpm glibc-dummy-centos-3 and erase it by

yum erase glibc-dummy-centos-3

glibc-dummy-centos-3 is developed by swsoft. glibc postinstall scripts create a 30-mb big
file /usr/lib/locale/locale-archive.

The only purpose of this glibc-dummy-centos-3 package is to move the file to the template area in order to save 30MB of disk space per every centos-3 based VPS. It is save to deinstall this package from a VPS before upgrading glibc.

On all the VPSs the iptables modules are not enabled by default , and usually client get below error in this case :

“iptables v1.2.8: can’t initialize iptables table `filter’: Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.”

The iptable modules can be enabled through shell or vzmc , through vzmc you can simply select the modules , press enable and the vps will get restarted and the iptables modules will be enabled. Before enabling iptables on VPS, it needs to make sure that the iptables modules are enabled on the Hardware Node. In order to enable iptables modules on Hardware Node, edit /etc/sysconfig/iptables-config file on a Virtuozzo hardware node and look for the following parameter value:

IPTABLES_MODULES=”ipt_REJECT ipt_tos ipt_TOS ipt_LOG ip_conntrack ipt_limit ipt_multiport iptable_filter iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_state iptable_nat ip_nat_ftp”

Also edit /etc/sysconfig/vz file on a hardware node and look for the following parameter value:

IPTABLES=”ipt_REJECT ipt_tos ipt_TOS ipt_LOG ip_conntrack ipt_limit ipt_multiport iptable_filter iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_state iptable_nat ip_nat_ftp”

Next step would be enabling iptables modules on VPS. This is how we can do it:

VEID=XXX (where XXX is the actual VPS ID that can be checked using “vzlist -a” command)

vzctl stop $VEID ; 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

vzctl set $VEID –numiptent 2000 –save

vzctl start $VEID

Virtuozzo VPS is composed of several parameters that are called QOS Parameters. These parameters define all the resources i.e disk space, memory, cpu, disk inodes etc for that VPS.  The parameters are defined inside VPS configuration file. A file /proc/user_beancounters inside the VPS contains the real time usage figures for these parameters. RAM statistics can be calculated for any Virtuozzo Linux VPS using these Formulas:

Guaranteed memory = barrier of vmguarpages / 1024 * 4
Burstable memory = privvmpages / 1024 x 4
Current Memory Usage= physpages held value /1024 * 4
Current Usage (RAM + SWAP)= oomguarpages held value /1024 * 4

In Windows Virtuozzo, all Windows upgrades need to be installed on Hardware Node instead of VPS. If  Windows upgrades will be installed inside VPS and those upgrades are not installed on Hardware Node, the VPS will be corrupted and it won’t start up on reboot. In thie case, all system files in system32 and system32\drivers folder need to be replaced with the system files from Hardware Node to start the VPS. These commands can be used to replace the system files inside VPS.

copy /y  C:\WINDOWS\system32  C:\vz\root\VE_ID\C\WINDOWS\system32
copy /y  C:\WINDOWS\system32\drivers  C:\vz\root\VE_ID\C\WINDOWS\system32\drivers

(NOTE: Replace System Drives and path as per the installation)

In Virtuozzo 3, vzagent0 user was used to connect to VZMC (Virtuozzo Management Console). As a regular practice passwords are changed so after resetting vzagent0 password, its recommended to clear the SSH authorized keys too. Following commands can be used to clear the SSH authorized keys for vzagent0.

On Linux Nodes:

vzctl exec 1 “> /home/vzagent0/.ssh/authorized_keys2″

on Windows Nodes:

vzctl exec 1 cmd /c del “c:\Program Files\OpenSSH\home\vzagent0\.ssh\authorized_keys2″

Virtuozzo Power Panel allows the Full VPS backup to be generated but the number of allowed backups is limited. Number of backups is defined on the HW node and used for all VPSs. For example two different VPSs on the same node couldn’t have different number of backups.

You could set number of backups by the following ways:

1. In the file – /etc/sysconfig/vzagent/vzagent.conf you should change the following string:

<pe_backups_limit>1</pe_backups_limit>

and restart vzagent – vzagent_ctl restart

2. In the VZMC:

Select Virtuozzo node > Tasks > Manage VZAgent Configuration > backm > configuration > pe_backups_limit

I have seen this issue many times when clients complain that they cannot login to VPS using RDP. Most of the time its because they turn Windows Firewall On but do not configure it so it just denies access to everything. Following commands can be executed from the command prompt of Node to turn Windows Firewall Off inside any VPS and set the Firewall services to not start automatically.

vzctl exec VEID net stop ipnat
vzctl exec VEID net stop policyagent
vzctl exec VEID sc config policyagent start= demand
vzctl exec VEID sc config ipnat start= demand

(NOTE: Replace VEID with actual VPS IP that can be checked by “vzlist -a” command)

New Plesk versions 8.6+ comes with MSDE (Microsoft SQL Desktop Edition) by default so you just need to follow the below mentioned steps in order to configure it.In earlier Plesk versions, MSDE needs to be installed. This can be done by downloading the MSDE from Microsoft site or installing “msde” virtuozzo template. Virtuozzo template can be installed to VPS using VZMC or “vzpkgadd” command. Read the rest of this entry »

In Virtuozzo, we can migrate a VPS from one hardware node to another using “vzmigrate” command. The migration will also include the IP addresses so you do not have to go back and re-add them. We may need to clear the arp cache for the IP to begin routing to the new network device.  If you are stopping the VPS prior to the migration then arp cache should not be a problem. I am taking VZNodeA and VZNodeB for reference and migrating a VPS from VZNodeA to VZNodeB. Read the rest of this entry »

Nowadays everyone prefers watching a video rather than reading the text. Youtube has introduced a new concept for information sharing. There are several vendors who offer product to provide the  functionality like youtube and these softwares require some modules that are usually called video sharing modules. Here is a quick way to install these modules. Read the rest of this entry »