HowTo: Password lesslogin in linux.

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Password less logins allow you get get into the server even the password has been changed or expired ,

It can be achieve by single unix command you can use either this or the detailed steps given below. It will prompt password for server2,  once it is over the next login will be the password less

 [root@srv-51 ~]$ ssh-copy-id -i ~/.ssh/  syncfuser@

Detailed steps :

1, Generate public key on server-1, ignore this step if it is already exist

 [root@srv-51 ~]$ ssh-keygen
 Generating public/private rsa key pair.
 Enter file in which to save the key (/root/.ssh/id_rsa):
 Created directory '/root/.ssh'.
 Enter passphrase (empty for no passphrase):
 Enter same passphrase again:
 Your identification has been saved in /root/.ssh/id_rsa.
 Your public key has been saved in /root/.ssh/
 The key fingerprint is:
 8f:99:9f:8f:ba:bf:15:ca:6b:1f:83:06:a2:1a:9c:59 root@srv-51
 The key's randomart image is:
 +--[ RSA 2048]----+
 | |
 | |
 | |
 | |
 | E . S . |
 | . + . . B o . |
 | = . + * + |
 | o o.= o |
 | . o=B+o |

3, Grab the key and add it in the authorized_keys file in server2

[root@srv-51 ~]# cat ~/.ssh/
 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAz9iTxsWIYZyLtGN47MQZkSrPqXoGwATAKD/ZqIyemFRvKnlkSllkEEQ7+MlMstz6HvONfTJuJROegELqTIA7PoR43LTTKw7zfqJtt1J4fUH/6mbYlB5bedXtl/7L9auRYr276d04CFUCKfINEG4KJXYlbuSM8Mr5ZiUvLCkiu4Jx77DSy0iWaDa90C6cEbl1vRX9yl1pdWQbAMuazYLfiDPOnbqb7JtcI9du5bNEuFuA26VahaYbaYtXFnKBbKrCUMzTHT2uuNesYpckUHT4f0T1fU9qNsAYBlyQBgMIu/2qdJ+Y8luMVCkydXx8ZJmSTmAp+yR+qaZDYCqujrvjdQ== root@localhost.localdomain

4, Server2 authorized_keys key entry is looks like this

[root@srv-52 ~]# cat /home/syncfuser/.ssh/authorized_keys
 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAz9iTxsWIYZyLtGN47MQZkSrPqXoGwATAKD/ZqIyemFRvKnlkSllkEEQ7+MlMstz6HvONfTJuJROegELqTIA7PoR43LTTKw7zfqJtt1J4fUH/6mbYlB5bedXtl/7L9auRYr276d04CFUCKfINEG4KJXYlbuSM8Mr5ZiUvLCkiu4Jx77DSy0iWaDa90C6cEbl1vRX9yl1pdWQbAMuazYLfiDPOnbqb7JtcI9du5bNEuFuA26VahaYbaYtXFnKBbKrCUMzTHT2uuNesYpckUHT4f0T1fU9qNsAYBlyQBgMIu/2qdJ+Y8luMVCkydXx8ZJmSTmAp+yR+qaZDYCqujrvjdQ== root@localhost.localdomain

Finally output will be like this

 [root@srv-51 ~]# ssh syncfuser@
 Last login: Wed Jun 25 17:08:25 2014 from
 [syncfuser@srv-52 ~]$

Now server1 root user can enter password less to the syncfuser on server2. 🙂

HowTo: Tomcat Logging – log customized with {X-Forwarded-For}

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Tomcat is allowing us to track back logs with enamours of information by customizing the log pattern. There is preset patten is available, we can also implement is in single line

I enabled few more information like execution time , request size , cookies etc..

Default tag should be like this

<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"  
               prefix="localhost_access_log." suffix=".txt" pattern="common" resolveHosts="false"/>

Common : %{X-Forwarded-For}i %l %u %t “%r” %s %b
Combined : %{X-Forwarded-For}i %l %u %t %r %s %b %{User-Agent}i %{Referer}i %{Cookie}i

You can change either Common or Combined

I have implemented my own pattern like below, so it should more detailed

pattern="%h %{X-Forwarded-For}i %l %u %t  &quot;%r&quot; %s %b  &quot;%{User-Agent}i&quot; &quot;%{Referer}i&quot; &quot;%{Cookie}i&quot; %T"

Access Log pattern new look

----------------------------- - - - [18/Mar/2014:10:52:06 +0530]  "GET /ajax/norm/list/status?ids=23%2C11%2C9%2C7%2C6%2C5%2C2%2C1%2C HTTP/1.1" 200 42  "Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Firefox/24.0" "" "JSESSIONID=4FD1DBEB911CD2E19AA4798F9A26DCA8" 0.007
Log Details : : Remote host name (or IP address if resolveHosts is false)
– : X-Forwarded-For – : Remote logical username
– : Remote user that was authenticated
[18/Mar/2014:10:52:06 +0530]  : Date and time, in Common Log Format
GET /ajax/norm/list/…… : First line of the request (method and request URI)
HTTP/1.1 : Request protocol
200 : HTTP status code of the response
42 : Bytes sent, excluding HTTP headers (Content size)
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Firefox/24.0: User Agent : Referer
JSESSIONID=4FD1DBEB911CD2E19AA4798F9A26DCA8 : Cookie header
0.007 : Time taken to process the request, in seconds

Once every thing has been done you can restart the tomcat to make it effect, more options are given below

%a – Remote IP address
%A – Local IP address
%b – Bytes sent, excluding HTTP headers, or ‘-‘ if zero
%B – Bytes sent, excluding HTTP headers
%h – Remote host name (or IP address if resolveHosts is false)
%H – Request protocol
%l – Remote logical username from identd (always returns ‘-‘)
%m – Request method (GET, POST, etc.)
%p – Local port on which this request was received
%q – Query string (prepended with a ‘?’ if it exists)
%r – First line of the request (method and request URI)
%s – HTTP status code of the response
%S – User session ID
%t – Date and time, in Common Log Format
%u – Remote user that was authenticated (if any), else ‘-‘
%U – Requested URL path
%v – Local server name
%D – Time taken to process the request, in millis
%T – Time taken to process the request, in seconds
%I – current request thread name (can compare later with stacktraces)
%f – X-Forwarded-For IP address
%F – X-Forwarded-For address

Bash: History appending for multiple sessions

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I got a requirement for listing all the command history if  multiple terminal sessions using in different region for the single user. I followed the below steps.

step1 : Create a new file with the below entries

root@appserver:# cat /etc/profile.d/
function share_history {
 history -a
 history -c
 history -r
HISTTIMEFORMAT=`echo -e "33[1;34m%d/%h/%Y 33[1;31m%H:%M:%S 33[0m"`
shopt -u histappend

Step2: activate it in run-time

root@appserver:# source /etc/profile.d/

Now you can see the list of aged histories

Sample Output :

1005 26/Dec/2013 14:23:08 vi /etc/profile.d/
1006 26/Dec/2013 14:23:27 source /etc/profile.d/
1007 26/Dec/2013 14:23:31 history

Info: NFS Server&Client Setup

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Server Side

NFS share with read/write privilege for the specified UID and GID, So even root will denied to write or read in that particular mount point and completly secure from everything.

Install required packages of  NFS server.

apt-get install nfs-kernel-server nfs-common portmap

After the installation of NFS server edit /etc/exports fileand add a line as follows.

     ↓           ↓                            ↓
NFSsharepath | network | Options(Here we need to set user id and group id of tomcat user)

Restart nfs server after making necessary changes in  the exports file.

#service nfs-kernel restart

Client side Linux

Install nfs client packages on NFS client machine. Mount nfs share in the client machine.

apt-get install portmap nfs-common

Make the following entry in /etc/fstab/ /home/nfs   nfs rsize=8192,wsize=8192,timeo=14,intr
           ↓                        ↓         ↓
Network share details          Mount point   Filesystem

Client Side Windows

Install nfs services for windows through control panel add or remove windows component wizard.

Edit Windows registery and make changes as follows  in the registery.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ClientForNFS \CurrentVersion\Default

1, Create two DWORD values namely AnonymousUid and AnonymousGid
2, Set these values to the UID and GID as set in the  NFS server for tomcat user (Eg:-106,114)
3, Restart NFS service.

Go to all programs- Administrative tools- Services for network filesystem and Start service of ClientForNFS.
Select properties of clientfornfs and set permissions as per the requirement. (Eg:- Read&write permission for the

script: Bash script to backup MySQL databases.

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# Simple script to backup MySQL databases 
# You have to enter the credintials, the scritp will make backup of all the databases 
# including information schema and perfomance schema as well, and store it as a gunzip format 
# in the backup directory. Each databases are dump as seperate files. 
# This will maintain 30 days backup. If you need to extend, edit the WEIGHT as your own. 
# Website : , , 
# Created by : Anandbabu 
# Parent backup directory
#Enter multiple email ID using space
WEIGHT=30 # 30 days
# MySQL settings
#Creating file for email
[ ! -f ${Email_Content} ] && touch ${Email_Content} || :> ${Email_Content}
 for email in ${Email}
 cat ${Email_Content} | mail -s "Notification: Mysql Database Backup $@ from MyServer " ${email} -aFrom:Backup\<\>
# Read MySQL password from stdin if empty
if [ -z "${mysql_password}" ]; then
 echo -n "Enter MySQL ${mysql_user} password: " >> ${Email_Content}
 read -s mysql_password
# Check MySQL password
echo exit | mysql --user=${mysql_user} --password=${mysql_password} -B 2>/dev/null
if [ "$?" -gt 0 ]; then
 echo "MySQL ${mysql_user} password incorrect" >> ${Email_Content}
 E_mail Failed
 exit 1
 echo "MySQL ${mysql_user} password correct." >> ${Email_Content}
# Create backup directory and set permissions
backup_date=`date +%Y_%m_%d_%H_%M`
echo "Backup directory: ${backup_dir}" >> ${Email_Content}
mkdir -p "${backup_dir}"
chmod 700 "${backup_dir}"
# Get MySQL databases
mysql_databases=`echo 'show databases' | mysql --user=${mysql_user} --password=${mysql_password} -B | sed /^Database$/d`
# Backup and compress each database
for database in $mysql_databases
if [[ "$database" =~ "information_schema" || "$database" =~ "performance_schema" ]] ; then
 echo "Creating backup of \"${database}\" database" >> ${Email_Content}
 mysqldump ${additional_mysqldump_params} --user=${mysql_user} --password=${mysql_password} ${database} | gzip > "${backup_dir}/${database}.sql.gz"
 chmod 600 "${backup_dir}/${database}.sql.gz"

##Removing folder older than 30 days
echo "" >> ${Email_Content}
ECOUT=`find ${backup_parent_dir} -type d -ctime +$WEIGHT`
if [ -z $ECOUT ]; then
 echo "No more older backups to remove" >> ${Email_Content}
 E_mail Success
 echo "Following older backups are removed" >> ${Email_Content}
 for i in $ECOUT
 rm -rvf $i 1>>${Email_Content} 2>>${Email_Content}
 E_mail Success

Error: 500 OOPS: vsftpd: refusing to run with writable root inside chroot()

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Each time while am installing VSFTPD on ubuntu and enable chroot for the users it will refuse to login to the home directory because of write permission in its parent dir, to fix this I used the command

chmod a-w  /path/to/the/ftp/home

but is was most annoying and frustrating problem. I supposed to update the vsftpd package with security fix. the steps are below.

dpkg -i vsftpd_3.0.2-3_amd64.deb
echo "allow_writeable_chroot=YES" >> /etc/vsftpd.conf
echo "seccomp_sandbox=NO" >> /etc/vsftpd.conf
service vsftpd reload

now the FTP service will work calm in my server.

Error: While executing gem … (ArgumentError)

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After installing ruby with rails , I got few error to install gems packages manager seems to be broken. Everytime you try to use gem install gem_name, you get the following error:

ERROR:  While executing gem ... (Gem::GemNotFoundException)

I do the step below to upgrade rubygems, it will fine

gem install rubygems-update

Now I can install gems whatever I needed.