ServerPronto, Author at ServerPronto University

Support of the day June 2, 2011

Run File System Check in Linux / UNIX

# fsck

fsck is used to check and optionally repair one or more Linux file systems.

If no filesystems are specified on the command line, and the -A option is not specified, fsck will default to checking filesystems in /etc/fstab serial. This is equivalent to the -As options.

The exit code returned by fsck is the sum of the following conditions:
0 – No errors
1 – File system errors corrected
2 – System should be rebooted
4 – File system errors left uncorrected
8 – Operational error
16 – Usage or syntax error
32 – Fsck canceled by user request
128 – Shared library error
The exit code returned when multiple file systems are checked is the bit-wise OR of the exit codes for each file system that is checked.

Options:

-s

Serialize fsck operations. This is a good idea if you are checking multiple filesystems and the checkers are in an interactive mode. (Note: e2fsck(8) runs in an interactive mode by default. To make e2fsck(8) run in a non-interactive mode, you must either specify the -p or -a option, if you wish for errors to be corrected automatically, or the n option if you do not.)

-t fslist

Specifies the type(s) of the file system to be checked. When the -A flag is specified, only filesystems that match fslist are checked. The fslist parameter is a comma-separated list of filesystems and options specifiers. All of the filesystems in this comma-separated list may be prefixed by a negation operator ‘no‘ or ‘!‘, which requests that only those filesystems not listed in fslist will be checked. If all of the filesystems infslist are not prefixed by a negation operator, then only those filesystems listed infslist will be checked. Options specifiers may be included in the comma-separated fslist. They must have the format opts=fs-option. If an options specifier is present, then only filesystems which contain fs-option in their mount options field of /etc/fstab will be checked. If the options specifier is prefixed by a negation operator, then only those filesystems that do not have fs-option in their mount options field of /etc/fstab will be checked.

For example, if opts=ro appears in fslist, then only filesystems listed in /etc/fstabwith the ro option will be checked.

For compatibility with Mandrake distributions whose boot scripts depend upon an unauthorized UI change to the fsck program, if a filesystem type of loop is found infslist, it is treated as if opts=loop were specified as an argument to the -t option.

Normally, the filesystem type is deduced by searching for filesys in the /etc/fstab file and using the corresponding entry. If the type can not be deduced, and there is only a single filesystem given as an argument to the -t option, fsck will use the specified filesystem type. If this type is not available, then the default file system type (currently ext2) is used.

-A

Walk through the /etc/fstab file and try to check all file systems in one run. This option is typically used from the /etc/rc system initialization file, instead of multiple commands for checking a single file system. The root filesystem will be checked first unless the -P option is specified (see below). After that, filesystems will be checked in the order specified by the fs_passno (the sixth) field in the /etc/fstab file. Filesystems with a fs_passno value of 0 are skipped and are not checked at all. Filesystems with a fs_passno value of greater than zero will be checked in order, with filesystems with the lowest fs_passno number being checked first. If there are multiple filesystems with the same pass number, fsck will attempt to check them in parallel, although it will avoid running multiple filesystem checks on the same physical disk.

Hence, a very common configuration in /etc/fstab files is to set the root filesystem to have a fs_passno value of 1 and to set all filesystems to have a fs_passno value of 2. This will allow fsck to automatically run filesystem checkers in parallel if it is advantageous to do so. System administrators might choose not to use this configuration if they need to avoid multiple filesystem checks running in parallel for some reason — for example, if the machine in question is short on memory so that excessive paging is a concern.

-C

Display completion/progress bars for those filesystems checkers (currently only for ext2) which support them. Fsck will manage the filesystem checkers so that only one of them will display a progress bar at a time.

-N

Don’t execute, just show what would be done.

-P

When the -A flag is set, check the root filesystem in parallel with the other filesystems. This is not the safest thing in the world to do since if the root filesystem is in doubt things like the e2fsck (8) executable might be corrupted! This option is mainly provided for those sysadmins who don’t want to repartition the root filesystem to be small and compact (which is really the right solution).

-R

When checking all file systems with the -A flag, skip the root file system (in case it’s already mounted read-write).

-T

Don’t show the title on startup.

-V

Produce verbose output, including all file system-specific commands that are executed.

For more information visit: http://linux.about.com/od/commands/l/blcmdl8_fsck_.htm

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

Support of the day May 30, 2011

Check and open ports in CentOS / Fedora / Redhat

If you want to open or close a port for a Linux firewall you have to edit the rules in the iptables configuration. By default iptables firewall stores its configuration at /etc/sysconfig/iptables file. You need to edit this file and add rules to open port.

Here are the steps to open the port XY using the default visual editor vi:

Open port XY

Open file /etc/sysconfig/iptables:

# vi /etc/sysconfig/iptables

Append rule as follows:

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport XY -j ACCEPT

Save and close the file. Restart iptables:

# /etc/init.d/iptables restart

Verify that port is open

Run following command:

# netstat -tulpn | less

Make sure iptables is allowing port connections:

# iptables -L -n

For more information visit:

http://www.cyberciti.biz/faq/howto-rhel-linux-open-port-using-iptables/

Dedicated Server Pricing May 26, 2011

Triple Core Gamer – Server Special

Gamer legacy server special. With a triple-core AMD CPU and 8GB of RAM, this machine is tuned to give you the power and speed you need for gaming or other performance intensive applications.

– Triple Core AMD 8400+
– 8GB DDR2 RAM
– 2×40 GB Hard Drive
– 10 TB Traffic
– 100Mbps Connection

Support of the day March 24, 2011

Support of the day: Install 32-bit Software on 64-bit OS

This support solution is on installing a 32-bit app on an x64 system. Stated on the example of Java Development Kit installed on Fedora x64 bit.

Three layers are essential when it comes to 32/64bit compatibility:

– Processor

– Operating System

– Application

A 32 bit OS will run on a 32 or 64-bit processor, without any problems.

A 32-bit software on a 64 bit OS works but could cause difficulties even if the 64 bit systems are backward compatible with the 32-bit counterparts.

To run a 64 bit OS, you need support from its lower level (a 64-bit processor). Therefore a 64 bit OS does not work for a 32 bit CPU.

To run a 64-bit application, you need support from all lower levels (64 bit OS and 64-bit processor).

Linux commands:
Check your processor:

# cat /proc/cpuinfo

Check Kernel/System:

# uname -m

For our example, the perfect solution is to install a 64-bit version of JDK on the Fedora x64 bit operating system.

Here is the How-To-Do:

The first thing we need to do is get the JDK installer
JDK Home from Oracle.com

Once we have the installer in our local repository (as root):

chmod a+x  jdk-6u21-linux-x64-rpm.bin./jdk-6u21-linux-x64-rpm.bin

Next, we must add these two lines to the file: /etc/profile

JAVA_HOME=/usr/java/jdk1.6.0_21
pathmunge $JAVA_HOME/jre/bin after

At the end of the line that starts with export, we need to add this our JAVA_HOME variable, so the line should be like this:

export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE INPUTRC JAVA_HOME

Then, we need to execute the next statements. Hint: Copy all the lines as it were just one.

export JAVA_HOME=/usr/java/jdk1.6.0_21
export JAVA_ALTERNATIVE_PRIORITY=16021
/usr/sbin/update-alternatives --install /usr/bin/java java $JAVA_HOME/bin/java $JAVA_ALTERNATIVE_PRIORITY
/usr/sbin/update-alternatives --install /usr/bin/javadoc javadoc $JAVA_HOME/bin/javadoc $JAVA_ALTERNATIVE_PRIORITY
/usr/sbin/update-alternatives --install /usr/bin/appletviewer appletviewer $JAVA_HOME/bin/appletviewer $JAVA_ALTERNATIVE_PRIORITY
/usr/sbin/update-alternatives --install /usr/bin/javah javah $JAVA_HOME/bin/javah $JAVA_ALTERNATIVE_PRIORITY
/usr/sbin/update-alternatives --install /usr/bin/javac javac $JAVA_HOME/bin/javac $JAVA_ALTERNATIVE_PRIORITY
/usr/sbin/update-alternatives --install /usr/bin/jar jar $JAVA_HOME/bin/jar $JAVA_ALTERNATIVE_PRIORITY

Then, we export the alternatives:

/usr/sbin/update-alternatives --auto java
/usr/sbin/update-alternatives --auto javadoc
/usr/sbin/update-alternatives --auto appletviewer
/usr/sbin/update-alternatives --auto javah
/usr/sbin/update-alternatives --auto javac
/usr/sbin/update-alternatives --auto jar

To confirm that our installation is successful:

java -version

Should give us output like this:

[root@yourMachine]# java -version
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b02)
Java HotSpot(TM) 64-Bit Server VM (build 16.3-b01, mixed mode)

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

Further information:
http://www.techsupportalert.com/content/32-bit-and-64-bit-explained.htm

http://wporta.wordpress.com/2010/07/06/installing-jdk-in-fedora-13/

Support of the day March 21, 2011

Manage users with Webmin and POP3/SMTP

You can manage and create users with Webmin by:

System/Users and groups/Create a new user

More information:

http://doxfer.webmin.com/Webmin/WebminUsers

If you want to add new domains, for example:

[email protected]
[email protected]

You need to add those domains to

/etc/mail/local-host-names

then in

/etc/mail/virtusertable

enter

[email protected] john
[email protected] sally

john and sally are local users

and rebuild config with

make -C /etc/mail/

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

More information:

http://www.linuxselfhelp.com/quick/sendmail.html

Support of the day March 18, 2011

Software Management System yum

Managed system yum is software installation tool for Red Hat Linux and Fedora Linux. yum commands are typically run as.yum <command> <package name/s> By default, yum will automatically attempt to check all configured repositories to resolve all package dependencies during an installation/upgrade.

Here is a list of the most common and used yum commands:

yum list all

To list all packages that are available to use the commandyum.

yum install <package name/s>

Used to install the latest version of a package or group of packages. If no package matches the specified package name(s), they are assumed to be a shell glob, and any matches are then installed.

yum update <package name/s>

Used to update the specified packages to the latest available version. If no package name/s are specified, then yum will attempt to update all installed packages.

If the –obsoletes option is used (i.e. yum –obsoletes <package name/s>, yum will process obsolete packages. As such, packages that are obsoleted across updates will be removed and replaced accordingly.

yum check-update

This command allows you to determine whether any updates are available for your installed packages. yum returns a list of all package updates from all repositories if any are available.

yum remove <package name/s>

Used to remove specified packages, along with any other packages depend on the packages being removed.

yum provides <file name>

Used to determine which packages provide a specific file or feature.

yum search <keyword>

This command is used to find any packages containing the specified keyword in the description, summary, packager and package name fields of RPMs in all repositories.

yum localinstall <absolute path to package name/s>

Used when using yum to install a package located locally in the machine.

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

More info under:

http://www.centos.org/docs/5/html/5.1/Deployment_Guide/s1-yum-useful-commands.html

http://yum.baseurl.org/wiki/YumCommands

Support of the day March 14, 2011

Establish connection for FTP daemon

Here are three steps that are necessary for the FTP daemon to allow connections:

A non-root user must be created.
The vsftp daemon must be started, you can do this with “/etc/init.d/vsftpd start”.
The firewall must allow port 21. You can add the firewall run in Webmin or by editing /etc/sysconfig/iptables, then restarting the firewall with “/etc/init.d/iptables restart”

The FTP user will have permission in their home directory. In order for the FTP user to have permission to upload, create any folder or allow different access, it is needed to grant the user access to that location using chown or chmod.

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

Support of the day March 10, 2011

Configure WHM/cPANEL with a SSL Certificate

If you try to access CPanel WHM via https://server.domain.com:2087/ and the error â€œThere is a problem with this website’s security certificateâ€ comes up it can be because it uses a default SSL certificate loaded during the automated install and you need to update it with your personalized certificate.

To have a non-self-signed certificate you will need to create a certificate request using the domain and credentials you intend to connect with. Then upload that cert request to an SSL provider site where you have an account. After purchasing a certificate you can install it into CPanel.

Install a SSL Certificate for WHM port 2087 and cPanel port 2083:

1) Purchase / Install the Certificate for your fully qualified domain (ie: server.domain.com)

– You can find your fully qualified server URL in the WHM under:
>> Server Status >> Server Information (System Information)

– Then you will create a certificate for this domain under:
>> SSL / TLS >> Generate a SSL Certificate and Signing Request

– After purchasing your certificate, you will install the certificate under:
** THIS MAY SEEM SLOW – BE PATIENT – WAIT FOR A BOLD CONFIRMATION MESSAGE **
>> SSL / TLS >> Install a SSL Certificate and Setup the Domain

– After installation is complete, you can assign the new certificate to be your SHARED certificate under:
** This is NOT required but is a great benefit for your clients and helps brand your domain **
>> SSL / TLS >> Manage SSL Hosts

2) Test your new Certificate

– https://server.domain.com/
This should resolve and the cert should function properly before moving forward. If this does not work, you will need to review addition instruction on SSL installation.

– https://server.domain.com:2087/
This should NOT WORK but give you an invalid certificate error. The reason is that the certificate is installed for the domain only, and has not been assigned to the appropriate WHM/CPANEL services.

3) Install the CERT for the WHM and CPANEL Service (this is the step you don’t think about!!)

Service Configuration >> Manage Service SSL Certificates
> Select “Install New Certificate” for the “cPanel/WHM/Webmail Service”
> Select Domain this CRT is for “Browse”
> Pick the full server cert you installed “server.domain.com”
> Press “Submit” to install

4) Test your Service Certificate

https://server.domain.com:2087/

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

More information under:

Manage SSL Certs

Configure WHM cPanel SSL Certificate

Support of the day March 9, 2011

Change configuration settings in Apache with .htaccess files

When changing configuration settings in Apache using directives in .htaccess files make sure:

- – The full directory content is listed with: Â Â ls -a to view hidden file that start with “.”
- – ensure Apache can use .htaccess, it is necessary to verify that option is enabled
  - – enabled .htaccess in httpd.conf

How-To-Do:

http://httpd.apache.org/docs/2.2/howto/htaccess.html

ServerPronto offers the best affordable and secure hosting service in all dedicated server packages.

Support of the day March 7, 2011

Setup FTP Server

If you have problems setting up an FTP server or issues accessing your FTP site, here are two basic tips that have helped our customers before to make their FTP server work properly.