Solve the error "The specified domain either does not exist or could not be contacted"

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server
3. Click Edit, point to New, and then click DWORD Value.
4. In the New Value #1 box, type IgnoreRegUserConfigErrors, and then press ENTER.
5. Right-click IgnoreRegUserConfigErrors, and then click Modify.
6. In the Value data box, type 1, click Decimal, and then click OK.
7. Quit Registry Editor.

How to configure Apache to set the character encoding properly

To get the character encoding properly from apache, please follow the instruction below,

#cd /etc/httpd/conf

#cp -a httpd.conf httpd.conf.orig

#vi httpd.conf

Locate the line "AddDefaultCharset UTF-8" and disable it. After that save the httpd.conf file

#service httpd restart

Now Apache will work for character encoding properly.

Detect new HDD in Linux system without restart

1. Install sg3_utils and lsscsi package.
    # yum install –y sg3_utils lsscsi

2. Run the command as bellow, it will detect and activate the new disk.
    # /usr/bin/rescan-scsi-bus.sh -l

3. Run lsscsifor output
    # lsscsi

How to move /var folder to a new partition

1) make the new partition, & format with mkfs.ext3

2) mount the new filesystem in /mnt

# mkdir /mnt/newvar

# mount /dev/sdb1 /mnt/newvar

3) Go to single-user mode so that there is no rw activity on the directory during the process

# init 1

4) Backup data in var only (not the /var directory itself)

# cd /var

# cp -ax * /mnt/newvar

5) Rename the /var directory (to make sure this has worked before deleting it!)

# cd /

# mv var var.old

6) Make new var directory

# mkdir /var

7) Unmount the new partition

# umount /dev/sdb1

8) Remount it as /var

# mount /dev/sdb1 /var

9) If everything goes fine then put an entry into /etc/fstab

/dev/sdb1               /var                    ext3    defaults        0 0

Install VMware Tools from the Command Line

For ClearOS, RedHat and CentOS

#yum -y update
#yum -y install gcc make kernel-headers kernel-devel --if you are using PAE kernel then use "kernel-PAE-devel instead of kernel-devel"
#untar -zxf VMwareTools-8.6.0-425873.tar.gz  --locate the actual path
#cd vmware-tools-distrib
#./vmware-install.pl
#/etc/init.d/vmware-tools status   --successful install will show the message "vmtoolsd is running"
#done

A list of free Backup Software

Open source backup software for Linux

• http://code.google.com/p/flyback
• https://github.com/apenwarr/bup
• http://www.kigen.de/projects/bar/index.html
• http://clonezilla.org 
• http://www.amanda.org
• http://www.bacula.org
• http://lrs.linbox.org 
• http://backuppc.sourceforge.net
• http://www.dirsyncpro.org

How to generate SSL key in pem format

• Make a new ssl private key:

  • Generate a new unencrypted rsa private key in PEM format:

    openssl genrsa -out privkey.pem 1024
    

         You can create an encrypted key by adding the -des3 option.
    
    

• To make a self-signed certificate:

  • Create a certificate signing request (CSR) using your rsa private key:

    openssl req -new -key privkey.pem -out certreq.csr
    

         ( This is also the type of CSR you would create to send to a root CA for them to sign for you. )
    
    
  • Self-sign your CSR with your own private key:

    openssl x509 -req -days 3650 -in certreq.csr -signkey privkey.pem -out newcert.pem
    

• To make a certificate signed by your own certificate authority (CA):

  • Configure /etc/ssl/openssl.cnf and use CA.pl to create the CA private key and certificate:

    vi /etc/ssl/openssl.cnf
        /usr/lib/ssl/misc/CA.pl -newca
    

         Your copy of openssl.cnf and CA.pl may be located elsewhere.
    
    
  • Create an unsigned certificate using your rsa private key:

    openssl req -new -x509 -key privkey.pem -out cert.pem
    

  • Use your private key and your certificate to make a CSR:

    cat cert.pem privkey.pem | openssl x509 -x509toreq -signkey privkey.pem -out certreq.csr
    

  • Sign the certificate with the CA private key using the CSR you just made:

    openssl ca -in certreq.csr -out newcert.pem
        rm -f certreq.csr
    

• To install the signed certificate and private key for use by an ssl server:

  • The newcert.pem is the certificate signed by your local CA that you can then use in an ssl server:

    ( openssl x509 -in newcert.pem; cat privkey.pem ) > server.pem
        ln -s server.pem `openssl x509 -hash -noout -in server.pem`.0   # dot-zero
    

         ( The server.pem is a PEM file that can be used by apache along with the hash file. )
  
  
  You can view the contents of a CSR with:
  

  openssl req -noout -text -in certreq.csr
  

  You can view the contents of a certificate with:
  

  openssl x509 -noout -text -in newcert.pem
  

  You can display the MD5 fingerprint of a certificate with:
  

  openssl x509 -fingerprint -noout -in newcert.pem
  

  You can verify that your private key, CSR, and signed cert match by comparing:
  

  openssl rsa -noout -modulus -in privkey.pem |openssl md5
  openssl req -noout -modulus -in certreq.csr |openssl md5
  openssl x509 -noout -modulus -in newcert.pem |openssl md5
  

Zimbra Collaboration Server

If you're looking to run your own business oriented email server, then the Zimbra Collaboration Suite (ZCS) is perfect for you. It is an efficient mailing solution that streamlines the whole business communication system and allows smoother flow of information. It is very easy to manage and also cost effective.

It has very useful features like Ajax based emails as well as instant messenger with calendar, document management and task management. Zimbra can be used in an offline mode using it’s well managed Desktop Client which is very convenient to use, allows users to access their mail even in the absence of an internet connection. It has interface to access from mobile phone, as well as from iPhone and Android Phone. Zimbra also provide some kind of tools those can help to synchronize with MS Outlook and other Email client.

Zimbra emailing can now be done in a hierarchal format using the drag & drop features for mails and calendars along with contacts. It saves time and effort for the users and allows them to handle the workflow of the company in an easier manner while maintaining excellent level of quality.

Such excellent features and stability made Zimbra Collaboration Suite the best email server in the market today. As I know so many business organizations are now using the Zimbra mail server in their business environment.

Create and deploye 2048 bit certificate for Zimbra

For Zimbra simply execute the follwoing as root on the server console or putty/ssh terminal:

1. Create the Key file, it will ask for a password:

    openssl genrsa -des3 -out zimbra_password.key 2048

2. Now we want to remove that password

    openssl rsa -in zimbra_password.key -out zimbra.key

 

3. Now we want to req a new CSR, this will let us fill in the details as we see fit

    openssl req -new -key zimbra.key -out zimbra.csr

 

4. This will print us out the details of the CSR so we can verify we are happy with them

    openssl req -noout -text -in zimbra.csr

 

5. Now you will do your GeoCert thing

    cat zimbra.csr

 

6. Paste the contents into field at GeoCert.com

 

7. Now Retrieve the zip file for Apache, or anything else cuz its the same crap

 

8. upload the two file from the zip file to your server

    a. one is name domain.com.crt we need to copy that to commercial.crt

        cp domain.com.crt commercial.crt

    b. Now copy that commercial.crt to the correct zimbra location

        cp zimbra.key /opt/zimbra/ssl/zimbra/commercial/commercial.key

 

9. Now verify that the key will fit into the zimbra install

    /opt/zimbra/bin/zmcertmgr verifycrt comm /opt/zimbra/ssl/zimbra/commercial/commercial.key commercial.crt GeoTrust_CA_Bundle.crt

 

10. If that went well, install the cert

     /opt/zimbra/bin/zmcertmgr deploycrt comm commercial.crt GeoTrust_CA_Bundle.crt

 

11. Done.

How to apply SSL certificate to Zimbra-nginx multi-server v.7.1.1

Follow the steps:

1) acitvate proxy:
$ /opt/zimbra/libexec/zmproxyconfig -w -e -x redirect -H vm2.zimbra.lab

2) as root do the following:
# mkdir /opt/zimbra/conf/domaincerts
# cd /opt/zimbra/conf/domaincerts

3) Put your keys into this folder
a) basedomain.com.key (your private-key)
b) basedomain.com.crt (commercial.crt + intermediates + root_CA)
c) check the keys:
# /opt/zimbra/bin/zmcertmgr verifycrt comm ./basedomain.com.key ./basedomain.com.crt
d) deploy the certs:
# /opt/zimbra/libexec/zmdomaincertmgr deploycrts
e) save the certs:
# /opt/zimbra/libexec/zmdomaincertmgr savecrt basedomain.com basedomain.com.crt basedomain.com.key

4) as zimbra do the following
a) set proxy-mode for base-domain on proxy-server:
$ zmprov ms server.basedomain.com zimbraReverseProxyMailMode redirect
b) set proxy-mode on mailbox-server for intern communications to proxy-server (must be http !)
$ zmtlsctl http
c) test this:
$ zmprov gs `zmhostname` | grep -i mode
d) restart proxy:
$ zmproxyctl restart