http://forums.linuxnix.com is activate for Public

Hi all,

I am very much pleased to announce Christmas/New year gift for you people. We just started our new Linux/Unix forums to resolve our issues which we are facing on day to day basis at work as well as home. Please join hands with us to help others who are in need.

The forums can be accessed at http://forums.linuxnix.com
The forums are free to all
The forums does not require to register but we suggest you to register and post questions.

As a www.linuxnix.com admin I am very much awaited to see all you there discussing on various issues faced by you in Linux/Unix which will benefit us all.

Thanks,
Admin
http://www.linuxnix.com

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Facing Issue With Blogger. Posts On Apache Will Be Delayed

Hi all,

We are facing issues with posting apache posts on linuxnix.com. This is because the apache code is messing up with html rendring of blogger. So we are not able to post Virtulhost codes in the site. We will come up with a solution to resolve this issue. Mean time we are continuing with other posts. We will let you people know when we will start the apache posting once again.

Thanks,
Admin
http://www.linuxnix.com

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How To Access Web Server Through IP Address?

How to access web server through ip address(not the default site)?

Step1 : check for the package installed or not

#rpm -qa | grep httpd

Step2 : Install the package

#yum install httpd

Step3 : Create the root web directory and a test index.html for this testing.

I want to create my web directory in /ipbasehost

#mkdir /ipbasehost

Now create index.html and try to write something in to that file then save the file.

#vi /ipbasehost/index.html

save and exit the file.

Step4 : Now edit the httpd.config file

#vi /etc/httpd/conf/httpd.conf

Go to last line and write the below content

DocumentRoot /ipbasehost/

DirectoryIndex index.html

Save the file and exit.

Let me explain above four lines

=> This indicates we are creating a virtualhost who's IP addresse is 192.168.0.1

DocumentRoot /ipbasehost/ => This indicates where is my document root i.e., all my web content should be placed under /ipbasehost/ So this content will be published through website.

DirectoryIndex index.html => This indicates what is the default file to be open when this site is accessed. So when you type ip address(here its 192.168.0.1) in browser it will present with

index.html content.

=>This is to specify the end of that virtual host.

Now save the file and exit.

Step5 : Check for the syntax errors in the httpd.conf file before restarting the apache service.

#httpd -t

Or

#httpd -k graceful

Step6 : Now start the service and then add it to booting scripts so that it will start automatically at every boot of the system

#service httpd restart

#chkconfig httpd on

Step7 : Now check the site using 192.168.0.1 ip address in your browser.

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How To Install Apache Server Source Package On Linux Server?

How to install apache server source package on Linux server?

Step1 : Check if the package is installed or not

#find / -iname httpd.conf

If you did not find any thing related to apache by using above find command you can install the source package.

Step2 : We can install source package in /opt for our requirement. Download the package from apache software foundation site

#cd /opt

#wget http://mirror.cc.columbia.edu/pub/software/apache//httpd/httpd-2.2.17.tar.gz

Step3 : Uncompress it and change the directory to source directory

#tar xvfz httpd-2.2.17.tar.gz

#cd httpd-2.2.17

Step4 : Now compile the source code

#./configure

#make

#make install

Or

The above three commands can be clubbed together to save time

#./configure && make && make install

Note1 : All the configuration files related to apache are stored in /usr/local/apache2/ When we install the source package by default. But if we install it through package installation softwares such as rpm/yum/apt-get the configuration files are stored in /etc/httpd folder

Note2 : This is important and interview question too. Can we run two apache servers at a time?

Ans : The answer to this question is yes. And its possible if we use source package to install in two different locations say in /opt and /opt1 and the variable “Listen” is set to different. Ports for this two servers(Bit complex to understand. If you have any questions ask it at http://forums.linuxnix.com our new Linux/Unix forums not officially announced.

Step5 : Now start the service.

#/usr/local/apache2/bin/apachectl start

Step6 : Check if the web server is running or not by accessing local host

#elinks localhost

Or

Access localhost from browser

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How To Install Apache Server On Ubuntu Machine?

How to install an Apache Server on ubuntu machine(A debian system)?

Step1 : Check if the package is installed or not

#dpkg -l | grep apache

This dpkg -l command is similar to rpm -qa command in Redhat linux to list all the applications installed in your system.

Step2 : Install the package if you did not get any output

#apt-get install apache*

Step3 : Now start the apache service

#service apache2 restart

Step4 : On the service at booting time

#chkconfig apache2 on

Step5 : Check if the web server is running or not by accessing local host

#elinks localhost

Or

Access localhost from browser

Here is the screen shot showing the test web page when apache is installed

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Apache Server Installation On Redhat Linux

How we can install Apache web server on Redhat linux?
Ans : The simplest way to install Apache on redhat machine is to use yum command. 


Follow below steps : 
To install and check if the web server is running with default test page.


Step1: Check if the package is installed or not


#rpm -qa | grep httpd


Step2 : Install the package if you did not get any output


#yum install httpd


Step3 : Now start the apache service


#service httpd restart


Step4 : On the service at booting time


#chkconfig httpd on


Step5 : Check if the web server is running or not by accessing local host


#elinks localhost


or 


Access localhost from browser


When you access the server through browser red-hat Linux will present you with a test page as shown below

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Many How to's Related To Apache Web Server Is Going To Come On linuxnix.com

Hi all,
From today on words we are planing to provide in depth knowledge base on many Howto's related to Apache web server. Some of the howto's which we are going to present are as follows.

1. About Apache web server
2. Apache installation[Redhat/Debian]
3. Apache installation through source
4. Apache ip based web access
5. Apache host based web access
5a.Hosting multiple SSL websites on single host

6. Apache authentication based web access
7. Apache SSL based web access
8. Apache integration with AD(Active Directory) authentication

9. Apache log monitoring

10.Apache web server security

11.Troubleshooting apache
12.Apache fine tuning

And many more to come.

For any queries please feel to comment on this or mail us at surendra@linuxnix.com and feel free to ask if we miss something to post about Apache web server. If you like our posts please refer our site to your friends and spread the knowledge.

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How To Configure And Install Sendmail In Linux?

Send mail is one of the old and widely used mail delivery agent/Mail system.

First Please check this link to know more about Mail Server

Configuration Of Sendmail :

1. All the sendmail configuration files are located at /etc/mail

2. Main configuration files are access, sendmail.mc and send mail.cf.

3. In this example my domain is example.com and my mail server host-name is mx.example.com

Step1 : Install sendmail packages

#yum install sendmail*

#yum install m4

Step2 : Configure DNS entries in forward look-up zone file

#vi /path/to/your/forward/lookup/zone/file

mx1.example.com. IN MX 10 example.com.

Save the file and exit.

Step3 : Check for configuration errors and reload the DNS server

#named-checkzone example.com /path/to/your/forward/lookup/zone/file

#service named reload

Step4 : All the sendmail configuration files are stored in /etc/mail and now configure relay ip address list

Why we require this relay list?

Ans : This is because to secure your sendmail not get spam. So what ever Network/host-names you specified in this access file those networks/host-names only get access to our sendmail.

#vi /etc/mail/access

Entries as follows.

192.168.0.0/24 RELAY

Save and exit the file

Step5 : Now update the file to sendmail database with makemap command

Note : After executing below command you will find access.db, this is the indication that your makemap command worked perfect and database have been updated successfully.

Note : So if you want to relay more networks you have to edit access file.

#makemap hash access < access

Step6 : Configure sendmail.mc file

#vi /etc/mail/sendmail.mc

Step6(a) : Search for "confAUTH_OPTIONS" with out quotes open a new line after that and enter below entry in that line

define(`confDOMAIN_NAME', 'example.com')dnl

Caution : When using the quotes, "`" opening quote is near to escape key and "'" closing quote is at enter key.

Step6(b) : Search for 127.0.0 line and comment that line if its not commented.

dnl #DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

Step6(c) : Search for LOCAL_DOMAINN with out quotes and modify the line as below from.

LOCAL_DOMAIN(`localhost.localdomain')dnl

to

LOCAL_DOMAIN(`mx.example.com')dnl

Step6(d) : Search for "MASQUERADE_AS" with out quotes and modify the line as below from..

dnl MASQUERADE_AS(`mydomain.com')dnl

to

MASQUERADE_AS(`example.com')dnl

Now save the file and exit

Step7 : Now compile sendmail.mc changes to reflect them in sendmail.cf

#m4 sendmail.mc > sendmail.cf

Step8 : Now start/restart the sendmail service

#service sendmail restart

Step9 : Now add the sendmail service to chkconfig list to start automatically at booting times

#chkconfig sendmail on

Dovecot Configuration :

Step1 : Install the dovecot package

#yum install dovecot

Step2 : Search for "protocols" in /etc/dovecot.conf file and replace with below mention line.

#vi /etc/dovecot.conf#protocols = imap imapsReplace this to

protocols = pop3 imap imaps

Step3 : Start the dovecot service.

#service dovecot restart

Step4 : Now add the dovecot service to chkconfig list to start automatically at booting times

#chkconfig dovecot on

Testing the mail server

Step1 : Try sending mail using telnet command

#telnet mx.example.com 25

Server responds with: 220 mx.example.com SMTP then type HELLO

HELLO

Now Server responds with: 250 OK now send MAIL FROM:root@example.com

MAIL FROM:root@example.com

Now Server responds with: 250 Address Ok. Now type

RCPT TO:user@example.com

RCPT TO:user@example.com

Now Server responds with: 250 user@example.com OK. now type DATA to enter mail content.

DATA

Now Server Responds (or may not): 354 Enter Mail

Enter message, then on a new line,.

exit

Now the message will be sent to user@example.com.

Now log-in to that user and try to see the mail.

#su

user$mail

Here you can see your mail.As send mail configuration is huge and depends on the requirement. Here the configuration which I have shown you is basic configuration.

Some FAQ's:

Q. What is the port number for SMTP?

Ans : 25

Q. What is the port number for POP3, IMAP?

Ans : 110, 143

Q. What is present sendmail version?

Ans : 8

Q. What are other highly used mail servers in world?

Ans : qmail, exchange etc

Do you want to find port numbers to other

protocols too?

Use google squared. My example is here

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How To Upgrade An Installed Source Package?

I have installed a package from source, now I want to upgrade the older version to new version which is available.


How can I upgrade already installed source package on my system?


Ans : This question arises to all the admins who do installation from source package. To upgrade a source package follow the same steps to you have did at the time of first installation through source. Package as shown below..


Step1: unpack the new source code in tmp directory.


#cd /tmp
#tar xvfz packagname.tar.gz
#cd packagename
#./configure –prefix=/path/to/old/installation
#make
#make check
#make install


Step2 : Now check what is the version if its updated to new version for example


If you install squid then execute below command


#squid -v

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Troubleshooting Steps Of Tomcat Server

Troubleshooting Steps to check whether the Tomcat server is runing or not?

Step1 : Check ps command output

#ps -ef | grep tomcat

Step2 : Check with nmap whether port 8080 is opened or not?

#nmap localhost

Step3 : Check with telnet command as shown in below by executing GET / HTTP/1.0 Host: localhost command once logged in to server at 8080 port.

#telnet localhost 8080 Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape character is '^]'. GET / HTTP/1.0 Host: localhost

This command should output hte test tomcat page.

Enjoy the troubleshooting:)

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How To Install Apache Tomcat on Linux(Redhat/Ubuntu)?

How to install Apache tomcat on Linux(Redhat/Ubuntu)?

What is Apache tomcat?
Ans : ApacheTomcat is an open source web application server which supports J2ee Servlets, JavaServer, Pages(JSP) and API's. Tomcat should not be confused with Apache web server which an HTTP web server.
---Wikipedia.

Some terminology about Apache tomcat.

Apache Tomcat can be configured by editing server.xml file. Those who knows apache web server. This server.xml can be taken as synonimas to httpd.conf file.

Servlet is defined as a way add dynamic content to a Web server using the Java platform. And a servlet container is a compiled, executable program. The servlet container name is tomcat is catalina.

Pre requists for Apache tomcat are
1. java
2. JDK

Step by step for installing Apache tomcat

Note : Avoide installing tomcat from reposatories, always prefer to install it from source downloaded from apache site.

Step1 : Install all the prequistes

Redhat :

#yum install java

Ubuntu :

#apt-get install java

Step2 : Download tomcat source package and uncompress it.
Redhat/Ubuntu
#cd /opt
#wget http://www.trieuvan.com/apache/tomcat/tomcat-6/v6.0.29/bin/apache-tomcat-6.0.29.tar.gz
#tar xvfz apache-tomcat-6.0.29.tar.gz

Step3 : Setup the paths for Catalina and others.
Setting catalina paths

Redhat/ubuntu

CATALINA_HOME=/opt/apache-tomcat-6.0.29
CATALINA_BASE=/opt/apache-tomcat-6.0.29

Setting java paths

Check what java versions are installed in your system

#update-alternatives --config java

This command will display which is default java version used by your machine.

Example output :

# update-alternatives --config java

There are 2 programs which provide 'java'.

Selection Command
-----------------------------------------------
1
/usr/lib/jvm/jre-1.4.2-gcj/bin/java
*+ 2
/usr/lib/jvm/jre-1.6.0-openjdk/bin/java

Enter to keep the current selection[+], or type selection number:

If you see above the default java version is 1.6 so set the path to /usr/lib/jvm/jre-1.6.0-openjdk

JAVA_HOME=/usr/lib/jvm/jre-1.6.0-openjdk
JDK_HOMe=$JAVA_HOME

Step4 : Now start tomcat server

#/opt/apache-tomcat-6.0.29/bin/sartup.sh

Sample output.

Using CATALINA_BASE: /opt/apache-tomcat-5.5.26
Using CATALINA_HOME: /opt/apache-tomcat-5.5.26
Using CATALINA_TMPDIR: /opt/apache-tomcat-5.5.26/temp
Using JRE_HOME:
/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0/

Step5 : By default Apache Tomcat will be hosted onlocalhost : 8080 port by default. So try to access the site with web browser

http://localhost:8080
or
http://localhost:8080
or
http://systemname:8080

Stay tuned to other posts about troubleshooting tomcat installation.

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How To Set Java Path In Linux?

How to set java path in Linux?

Ans : Check where java is installed by using below command

#update-alternatives --config java
This command will show installed java packages in your machine.

Example output :
# update-alternatives --config java

There are 2 programs which provide 'java'.

Selection ----------------------------------------------- 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java *+ 2
From above you can see java version in use it. 1.6.

Setting java path(In Temporary way)

#JAVA_HOME=/usr/lib/jvm/jre-1.6.0-openjdk #export $JAVA_HOME

Setting java path (In Permanent way)
Edit ~/.bashrc and place below two lines in that file and save the file.

Vi ~/.bashrc
JAVA_HOME=/usr/lib/jvm/jre-1.6.0-openjdk export $JAVA_HOME

Now save the file and exit, then logout and login to make those changes to reflect.

Command

/usr/lib/jvm/jre-1.6.0-openjdk/bin/java

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How to Set Priority for a service at booting of Linux

This is possible with renaming of the scripts located in running configuration(rc) folders. As you people know that
all the startup scripts are stored in rc1.d, rc2.d etc... each of these folders corresponding to scripts to be started in that run-level 
for example.. if you want to start some script in runlevel 1 they are kept in /etc/rc1.d folder so that when Linux is booting up these scripts are executed at runlevel 1.


So how can i set priority to my scripts/services?
Just go in to one of the rc folders, you can see all the scripts which are started in that runlevel.. 
if you observe those scripts, these scripts will start with different numbers. here are some for your reference.

K09apache2
K15pulseaudio
K20acpi-support
K20kerneloops
K20saned
K20speech-dispatcher
K20virtualbox-ose
K20virtualbox-ose-guest-utils
K74bluetooth
README
S30killprocs
S70dns-clean
S70pppd-dns
S90single

so the script(services) start sequence will be like K09apache2 then K15pulseaudio so on.. so if you want to give priority to your service just name with less number.. as shown below..


K09apache2
K01pulseaudio
K20acpi-support
K20kerneloops
K20saned
K20speech-dispatcher
K20virtualbox-ose
K20virtualbox-ose-guest-utils
K74bluetooth
README
S30killprocs
S70dns-clean
S70pppd-dns
S90single


So now the first script/service which start in this list is K01pulseaudio


Please comment your thoughts on this..

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How To Change The Java Version In Linux?

This post is regarding how to change java version if multiple java versions are installed?


Check what are the java versions are installed on your system


#java -version


Example output

OpenJDK Runtime Environment (build 1.6.0-b09)

OpenJDK Client VM (build 1.6.0-b09, mixed mode)


So now I want to change the one version to another version.

If more than one java is installed. Execute below command to see how many java versions are installed? And what is the default version (Default version will be indicated by *)


#update-alternatives --config java


This command will display which is default java version used by your machine..

Example output.

# update-alternatives --config java


There are 2 programs which provided 'java'.


Selection Command


-----------------------------------------------


1. /usr/lib/jvm/jre-1.4.2-gcj/bin/java


*+ 2 /usr/lib/jvm/jre-1.6.0-openjdk/bin/java


Enter to keep the current selection[+], or type selection number:


So if you want to change the java version from 1.6 (now 2 is default version as shown) to 1.4 just press “1” with out quotes.

Please let us know if you know other way of changing java version.

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How To Enable Verbose Mode For SSH Logins?

How we can login to remote server through ssh?

#ssh user@servername

or

#ssh -l user servername

or

#ssh ip-add

So when you will execute the above command you will get the password prompt. But if you want to see what will happen when you execute ssh command you have to enable verbose or debugging mode. To do this we have to apply -v option at the time of login as shown in below example.

#ssh -v surendra@ftp2.linuxnix.com


root@krishna:/home/surendra# ssh -v surendra_a@ftp2.linuxnix.com
OpenSSH_5.5p1 Debian-4ubuntu4, OpenSSL 0.9.8o 01 Jun 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to ftp2.linuxnix.com [92.32.56.78] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 1.99, remote software version OpenSSH_4.0
debug1: match: OpenSSH_4.0 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.5p1 Debian-4ubuntu4
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'ftp2.linuxnix.com' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Next authentication method: keyboard-interactive
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Next authentication method: password
surendra_a@ftp2.linuxnix.com's password:
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_IN
Last login: Thu Dec 9 20:02:47 2010 from 1.23.6.79


After logout


debug1: client_input_channel_req: channel 0 rtype exit-status reply 0


debug1: channel 0: free: client-session, nchannels 1
Connection to ftp2.linuxnix.com closed.
Transferred: sent 2072, received 2072 bytes, in 27.7 seconds
Bytes per second: sent 74.8, received 74.8
debug1: Exit status 0


So if you want more verboseness you can use up to 3rd level(-vvv) as shown below

#ssh -vvv surendra_a@ftp2.linuxnix.com

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