*** Introduction –

All you know about the haproxy, that its the one of the good opensource load balancing software and to check the fun stats of haproxy here we using ‘socat’ – Multipurpose relay (SOcket CAT)

* What is socat?

Socat  is  a  command  line based utility that establishes two bidirectional byte streams and transfers data between them. Because the streams can be constructed from a large set of different types of data sinks and sources (see address  types),  and  because  lots  of address options may be applied to the streams, socat can be used for many different purposes. (see more info at ‘man socat’ or at http://www.dest-unreach.org/socat/)
* How to use ’socat’ with haproxy stat

Step 1) Download ’socat’ from http://www.dest-unreach.org/socat/download/  latest version ~ “socat-2.0.0-b3.tar.gz”

ravi@arun:~$ wget http://www.dest-unreach.org/socat/download/socat-1.7.1.2.tar.gz

ravi@arun:~$ tar xvzf socat-1.7.1.2.tar.gz

ravi@arun:~$ cd socat-1.7.1.2

NOTE ~ No need to install the ‘fipsld’ package if you got the below msg after running the ‘make’ just following steps for

compiling socat….

FIPSLD_CC=gcc fipsld -O -D_GNU_SOURCE -Wall -Wno-parentheses  -DHAVE_CONFIG_H -I.  -I.   -c -o socat.o socat.c
/bin/sh: fipsld: command not found
make: *** [socat.o] Error 127

ravi@arun:~$ ./configure –disable-fips
ravi@arun:~$ make

To install it login as root
ravi@arun:~$ su -

ravi@arun:~# make install

Step 2) Now you need to add stats socket PATH in Haproxy configuration and restart haproxy as per shown in following example,

where I have added it under in ‘global’ setting -

ravi@arun:~# more /etc/haproxy/myhaproxy.cfg

#———–Start of haproxy Config file————–
global
log 127.0.0.1   local0
log 127.0.0.1   local1 notice
#log loghost    local0 info
maxconn 25000
#debug
#quiet
user ravi
group ravi
stats socket    /tmp/haproxy
defaults
option          contstats
timeout         connect 5s
timeout         client 25s
timeout         server 25s
maxconn         100

listen ravitestbed      0.0.0.0:80 ##ravi.com IP
mode            tcp
balance         roundrobin
server          web1 192.168.19.117
server          web2 192.168.19.122

listen stats
bind            0.0.0.0:8081
mode            http
#stats          uri /stat  #Comment this if you need to specify diff stat path for viewing stat page
stats enable
stats auth admin:admin ##Auth user pass

#———–End of haproxy Config file————–

Step 3) Used /tmp/haproxy. Now you can send the commands to get stats from HAProxy -

Now time to use socat

ravi@arun:~# echo “”  | socat unix-connect:/tmp/haproxy stdio
Unknown command. Please enter one of the following commands only :
show info   : report information about the running process
show stat   : report counters for each proxy and server
show errors : report last request and response errors for each proxy
show sess   : report the list of current sessions

This will dump (possibly huge) info about all know sessions.

ravi@arun:~$ echo “show sess” | socat unix-connect:/tmp/haproxy stdio
0×9ee3520: proto=tcpv4 src=192.168.19.117:4721 fe=ravitestbed be=ravitestbed srv=arun as=0 ts=08 age=4s calls=3
rq[f=009202h,l=0,an=00h,rx=20s,wx=,ax=] rp[f=009202h,l=0,an=00h,rx=20s,wx=,ax=] s0=[7,8h,fd=1,ex=] s1=[7,8h,fd=2,ex=] exp=20s
0×9eeb8e8: proto=tcpv4 src=192.168.19.117:4723 fe=ravitestbed be=ravitestbed srv=arun as=0 ts=08 age=4s calls=3
rq[f=009000h,l=0,an=00h,rx=20s,wx=,ax=] rp[f=009202h,l=0,an=00h,rx=20s,wx=,ax=] s0=[7,8h,fd=8,ex=] s1=[7,8h,fd=9,ex=] exp=20s
0×9ef3d08: proto=tcpv4 src=192.168.19.117:4725 fe=ravitestbed be=ravitestbed srv=arun as=0 ts=08 age=4s calls=3
rq[f=009000h,l=0,an=00h,rx=20s,wx=,ax=] rp[f=009202h,l=0,an=00h,rx=20s,wx=,ax=] s0=[7,8h,fd=12,ex=] s1=[7,8h,fd=13,ex=]
exp=20s
0×9f04548: proto=unix_stream as=2 ts=09 age=0s calls=2 rq[f=00e042h,l=10,an=20h,rx=10s,wx=,ax=]

rp[f=048060h,l=716,an=00h,rx=,wx=10s,ax=] s0=[7,0h,fd=3,ex=] s1=[0,0h,fd=-1,ex=] exp=9s

This will give you information about the running HAProxy process such as pid, uptime and etc.

ravi@arun:~$ echo “show info” | socat unix-connect:/tmp/haproxy stdio
Name: HAProxy
Version: 1.3.23
Release_date: 2010/01/28
Nbproc: 1
Process_num: 1
Pid: 11829
Uptime: 0d 0h42m53s
Uptime_sec: 2573
Memmax_MB: 0
Ulimit-n: 50013
Maxsock: 50013
Maxconn: 25000
Maxpipes: 0
CurrConns: 1
PipesUsed: 0
PipesFree: 0
Tasks: 1
Run_queue: 1
node: ravi.world
description:

This will give you stats on all of your backends and frontends, some of the same stuff you see on the stats page enabled by the stats uri configuration. As an added bonus it’s all in CSV.

ravi@arun:~$ echo “show stat” | socat unix-connect:/tmp/haproxy stdio
#
pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq,dresp,ereq,econ,eresp,wretr,wredis,status,weight,act,bck,chkfail,ch
kdown,lastchg,downtime,qlimit,pid,iid,sid,throttle,lbtot,tracked,type,rate,rate_lim,rate_max,
ravitestbed,FRONTEND,,,0,5,100,30,32582,50616,0,0,0,,,,,OPEN,,,,,,,,,1,1,0,,,,0,0,0,5,
ravitestbed,trupti,0,0,0,2,,15,7020,22722,,0,,0,0,0,0,no check,1,1,0,,,,,,1,1,1,,15,,2,0,,2,
ravitestbed,arun,0,0,0,5,,15,25562,27894,,0,,0,0,0,0,no check,1,1,0,,,,,,1,1,2,,15,,2,0,,3,
ravitestbed,BACKEND,0,0,0,5,100,30,32582,50616,0,0,,0,0,0,0,UP,2,2,0,,0,2710,0,,1,1,0,,30,,1,0,,5,
stats,FRONTEND,,,0,1,100,21,9605,152357,0,0,0,,,,,OPEN,,,,,,,,,1,2,0,,,,0,0,0,9,
stats,BACKEND,0,0,0,1,100,5,9605,152357,0,0,,5,0,0,0,UP,0,0,0,,0,2710,0,,1,2,0,,0,,1,0,,4,

show errors will give you a capture of last error on each backend/frontend.

ravi@arun:~$ echo “show errors” | socat unix-connect:/tmp/haproxy stdio

Reffer:

http://www.dest-unreach.org/socat/

http://haproxy.1wt.eu/download/1.3/doc/configuration.txt

Thanks to Joe (http://www.joeandmotorboat.com)

Thank you,
Ravi

Introduction:-

Access control to services compiled with TCP wrappers support is implemented by the /etc/hosts.allow and /etc/hosts.deny files. When a connection attempt is made, the hosts.allow file is checked. If a line is matched, the connection is allowed. Then the hosts.deny file is consulted, if a line is matched, the connection is denied. If no matches have occurred in either file, the connection is allowed.

Create Authorized Use Only Banners-

If configured as described below, TCP wrappers will display a warning banner to any user attempting to connect to a service it monitors. The following set of commands generate the directory /etc/banners, and the files therein contain warning banner text for each service. In this example, the banner text is “Use of this system is restricted to authorized users.” Note that exact wording of a warning banner is site specific; however, it should at least emphasize that the use of the system is restricted to authorized persons and that consent to monitor activities is implied by logging in to the system.

[root@localhost]# /bin/mkdir -p /etc/banners
[root@localhost]# /bin/echo “Use of this system is restricted to authorized users” > /etc/banners/
prototype
[root@localhost]# cd /etc/banners ; /usr/bin/make -f /usr/share/doc/tcp_wrappers-7.6/Banners.Makefile

Deny Everything Except What is Explicitly Allowed-

In order to implement the security best practice stance of deny everything except what is explicitly allowed, issue the following command.
[root@localhost]# echo ‘ALL: ALL: spawn (/bin/echo -e ‘/bin/date’”\n%c attempted connection to %s
and was denied” \
> | /bin/mail -s “Connection attempt to %s” root) &’ > /etc/hosts.deny

Any connection attempt not listed in the hosts.allow file will be denied, a message will be logged to the syslog auth facility, and an email will be sent to root.
Allow Access to Those Who Require It

Edit the hosts.allow file and add a line for each service to which access should be allowed. A few examples are shown below (See the man pages for hosts.allow for more detail).

ALL: LOCAL : banners /etc/banners            # All services from local clients (hostnames with no “.”)
sshd: 10.1.1.0/255.255.254.0 : banners /etc/banners # SSH connections from host IP addresses  between 10.1.1.0 and 10.1.2.0

Thanks
Manoj Chauhan

Introduction –

To conclude the discussion about session management, here are some best practices to demonstrate that a robust scheme requires serious thinking:
•    Create a session token upon first visit.
•    When performing authentication, destroy the old session and create a new one.
•    Limit session lifetime to a short period (a few hours).
•    Destroy inactive sessions regularly.
•    Destroy sessions after users log out.
•    Ask users to re-authenticate before an important task is performed (e.g., an order is placed).
•    Do not use the same session for a non-SSL part of the site as for the SSL part of the site because non-SSL traffic can be intercepted and the session token obtained from it. Treat them as two different servers.
•    If cookies are used to transport session tokens in an SSL application, they should be marked “secure.” Secure cookies are never sent over a non-SSL connection.
•    Regenerate session tokens from time to time.
•    Monitor client parameters (IP address, the User-Agent request header) and send warnings to the error log when they change. Some information (e.g., the contents of the User-Agent header) should not change for the lifetime of a session. Invalidate the session if it does.
•    If you know where your users are coming from, attach each session to a single IP address, and do not allow the address to change.
•    If you can, do not accept users coming through web proxies. This will be difficult to do for most public sites but easier for internal applications.
•    If you can, do not accept users coming through open web proxies. Open proxies are used when users want to stay anonymous or otherwise hide their tracks. You can detect which proxies are open by extracting the IP address of the proxy from each proxied request and having a script automatically test whether the proxy is open or not.
•    If you do allow web proxies, consider using Java applets or Flash movies (probably a better choice since such movies can pretend to be regular animations) to detect the users’ real IP addresses. It’s a long shot but may work in some cases.
•    Web users can upload only jpeg, gif, png files not php extension
•    We can place a blank index page in each directory in question and users can not execute php etc scripts from the image folders or image/document upload folders.
•    Upgrade apache current version (2.0) to newer version (2.2)

Thanks
Manoj Chauhan

Many times  haproxy and apache does not reliable to serve the connections without tune or we say we need to set system as well some kernel parameters to work it better.

Here haproxy gives an errors to connect to apache, at that time it logs the errors into ‘dmesg | tail’ or in ‘/var/log/messages’ “kernel: ip_conntrack: table full, dropping packet” that is related to ip_conntrack kernel module.

Conntrack table is hash table (hash map) of fixed size (8192 entries by default), which is used for primary lookup. When the slot in the table is found it points to list of conntrack structures, so secondary lookup is done using list traversal. 65536/8192 gives 8 – the average list length. You may want to experiment with this value on heavily loaded systems.

If this error founds into /var/log/messages or dmesg you have to apply following steps to resolve.

Here I have done this to changes and added few settings in kernel also we will do it to set apache MPM and Haproxy tunning with sysctl.conf

Note: I have tried all this workaround and apply on CentOS-5.2, but don’t worry ip_conntrack module is default in kernel 2.6 +

1) To check ip_contrack is compiled with your kernel

[root@ravi.com ~]# modinfo ip_conntrack
filename:       /lib/modules/2.6.18-128.el5/kernel/net/ipv4/netfilter/ip_conntrack.ko
license:        GPL
srcversion:     F1390E605BBFB05078B78E8
depends:        nfnetlink
vermagic:       2.6.18-128.el5 SMP mod_unload gcc-4.1
module_sig:     883f350497747c575ed35fe9471dce112565509f4b58f4f3e440c6bcc05c2fba9bbdd224bdeb8209e293da385133a876e44a7b449ba59a882a8282b

2) Probe ip_conntrack kernel module or add it in /etc/modprobe.conf

[root@ravi.com ~]# modprobe ip_conntrack hashsize=131072

or

open /etc/modprobe.conf and add below lines at the end of file

options ip_conntrack hashsize=131072

3) before go to apply the 4th step, just check the ip_conntrack setting is into /etc/sysctl.conf

grep “ip_conntrack” /etc/sysctl.conf

if its found then apply 4th step or edit the /etc/sysctl.conf and add the given two lines at the end of file and save it then go for 4th step
(the value is compare to your RAM and set it to below)

net.ipv4.ip_conntrack_max = 16777216
net.ipv4.netfilter.ip_conntrack_max = 16777216

4) To apply the sysctl parameters run ’sysctl -p’

[root@ravi.com ~]# sysctl -p

5) Now check the ip_conntrack is logging the connections and check not dropping any more

[root@ravi.com ~]# cat /proc/slabinfo | grep conn
ip_conntrack_expect      0      0    136   28    1 : tunables  120   60    8 : slabdata      0      0      0
ip_conntrack      216053 231335    304   13    1 : tunables   54   27    8 : slabdata  17795  17795    216

6) Also you can check how much memory utilized by ip_conntrack module per connection.

[root@ravi.com ~]# grep ip_conntrack /var/log/messages

/var/log/messages.2:Jan 14 21:46:04 ravi kernel: ip_conntrack version 2.4 (8192 buckets, 65536 max) – 304 bytes per conntrack

1M connections would require 304MB of kernel memory.

Thanks
Ravi

Here I have used php version 5.2.11 and to jdk-6u18-linux-x64.bin

( from given JAVA download link)

[root@ravi.com ~]# yum  -y install httpd php php-devel php-gd php-cli php-xml php-ldap php-common php-pear php-pdo

Install java jdk and set env in ~/.bashrc also run this on CLI to verify before next step.

export JAVA_HOME=//usr/java/jdk1.6.0_18
export PATH=/usr/java/jdk1.6.0_18/bin:$PATH

[root@ravi.com ~]# echo $JAVA_HOME

Now set the dynamic linker library path into /etc/ld.so.conf

/usr/java/jdk1.6.0_18/jre/lib/amd64
/usr/java/jdk1.6.0_18/jre/lib/amd64/server

[root@ravi.com ~]# ldconfig

Now download php-java-bridge source rpm

[root@ravi.com ~]# wget ftp://195.220.108.108/linux/sourceforge/p/project/ph/php-java-bridge/OldFiles/php-java-bridge-4.1.8-1.src.rpm

unpack the php-java-bridge rpm

[root@ravi.com ~]# rpm2cpio php-java-bridge-4.1.8-1.src.rpm | cpio -ivd
php-java-bridge.spec
php-java-bridge_4.1.8.tar.gz
16155 blocks

untar the php-java-bridge and configure the module

[root@ravi.com ~]# tar xzf php-java-bridge_4.1.8.tar.gz && cd php-java-bridge-4.1.8

[root@ravi.com ~]# phpize

[root@ravi.com ~]# ./configure –with-java=$JAVA_HOME  &&  make &&  make install

[root@ravi.com ~]# echo “extension=java.so” > /etc/php.d/java.ini

open the php.ini and edit the at the end of file

[java]
java.class.path=/usr/lib64/php/modules/
java.library=/usr/java/jdk1.6.0_18/jre/lib/amd64/server/libjvm.so

Now restart apache
[root@ravi.com ~]# /etc/init.d/httpd restart

[root@ravi.com ~]# php -i | grep java
/etc/php.d/java.ini,
java
java support => Enabled
java bridge => 4.1.8
java.java_home =>
java.java => java
java.log_file => <stderr>
java.log_level => no value (use back-end’s default level)
java.security_policy => Off
java command =>  LD_LIBRARY_PATH=/usr/lib64/php/modules:/usr/lib/10.2.0.3/client64/lib java -Djava.library.path=/usr/lib64/php/modules -Djava.class.path=/usr/lib64/php/modules/JavaBridge.jar -Djava.awt.headless=true -Dphp.java.bridge.base=/usr/lib64/php/modules php.java.bridge.Standalone LOCAL:9267 1
java status => running
java server => 9267
PATH => /usr/java/jdk1.6.0_18/bin:/usr/java/jdk1.6.0_18/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
JAVA_HOME => /usr/java/jdk1.6.0_18
_SERVER["PATH"] => /usr/java/jdk1.6.0_18/bin:/usr/java/jdk1.6.0_18/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
_SERVER["JAVA_HOME"] => /usr/java/jdk1.6.0_18
_ENV["PATH"] => /usr/java/jdk1.6.0_18/bin:/usr/java/jdk1.6.0_18/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
_ENV["JAVA_HOME"] => /usr/java/jdk1.6.0_18

Test your code in test.php and run to check
<?php
// get instance of Java class java.lang.System in PHP
$system = new Java(‘java.lang.System’); // demonstrate property access
print ‘Java version=’.$system->getProperty(‘java.version’).’ ‘;
print ‘Java vendor=’ .$system->getProperty(‘java.vendor’).’ ‘;
print ‘OS=’.$system->getProperty(‘os.name’).’ ‘.
$system->getProperty(‘os.version’).’ on ‘.
$system->getProperty(‘os.arch’).’ ‘; // java.util.Date example
$formatter = new Java(‘java.text.SimpleDateFormat’,
“EEEE, MMMM dd, yyyy ‘at’ h:mm:ss a zzzz”); print $formatter->format(new Java(‘java.util.Date’));
?>

[root@ravi.com ~]# php test.php
Java version=1.6.0_18 Java vendor=Sun Microsystems Inc. OS=Linux 2.6.18-53.el5xen on amd64 Friday, January 22, 2010 at 4:44:48 AM Pacific Standard Time
Thanks

Ravi

To enable pdo_oci module you may need to install oracle client and oci8 module is require. I have installed oracle 10g client here.

[root@ravi.com ~]# export ORACLE_HOME=/usr/lib/oracle/10.2.0.3/client64/ ; export LD_LIBRARY_PATH=/usr/lib/oracle/10.2.0.3/client64/
[root@ravi.com ~]# cd /tmp
[root@ravi.com tmp]# pecl download pdo_oci
[root@ravi.com tmp]# tar xvzf PDO_OCI-1.0.tar.gz
[root@ravi.com tmp]# cd PDO_OCI-1.0 && phpize
[root@ravi.com tmp]# ./configure
[root@ravi.com PDO_OCI-1.0]# make
/bin/sh /tmp/PDO_OCI-1.0/libtool –mode=compile gcc -I/usr/include/php/ext -I. -I/tmp/PDO_OCI-1.0 -DPHP_ATOM_INC -I/tmp/PDO_OCI-1.0/include -I/tmp/PDO_OCI-1.0/main -I/tmp/PDO_OCI-1.0 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext  -DHAVE_CONFIG_H  -g -O2   -c /tmp/PDO_OCI-1.0/pdo_oci.c -o pdo_oci.lo
mkdir .libs
gcc -I/usr/include/php/ext -I. -I/tmp/PDO_OCI-1.0 -DPHP_ATOM_INC -I/tmp/PDO_OCI-1.0/include -I/tmp/PDO_OCI-1.0/main -I/tmp/PDO_OCI-1.0 -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -DHAVE_CONFIG_H -g -O2 -c /tmp/PDO_OCI-1.0/pdo_oci.c  -fPIC -DPIC -o .libs/pdo_oci.o
In file included from /tmp/PDO_OCI-1.0/pdo_oci.c:31:
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:21:17: error: oci.h: No such file or directory
In file included from /tmp/PDO_OCI-1.0/pdo_oci.c:31:
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:26: error: expected specifier-qualifier-list before ’sb4′
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:32: error: expected specifier-qualifier-list before ‘OCIServer’
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:48: error: expected specifier-qualifier-list before ‘OCIDefine’
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:62: error: expected specifier-qualifier-list before ‘OCIStmt’
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:73: error: expected specifier-qualifier-list before ‘OCIBind’
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:85: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘PDO_OCI_INIT_MODE’
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:87: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/tmp/PDO_OCI-1.0/php_pdo_oci_int.h:89: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘_oci_error’
/tmp/PDO_OCI-1.0/pdo_oci.c:71: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘PDO_OCI_INIT_MODE’
/tmp/PDO_OCI-1.0/pdo_oci.c:87: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/tmp/PDO_OCI-1.0/pdo_oci.c: In function ‘zm_startup_pdo_oci’:
/tmp/PDO_OCI-1.0/pdo_oci.c:96: error: ‘pdo_oci_Env’ undeclared (first use in this function)
/tmp/PDO_OCI-1.0/pdo_oci.c:96: error: (Each undeclared identifier is reported only once
/tmp/PDO_OCI-1.0/pdo_oci.c:96: error: for each function it appears in.)
/tmp/PDO_OCI-1.0/pdo_oci.c:96: error: ‘PDO_OCI_INIT_MODE’ undeclared (first use in this function)
/tmp/PDO_OCI-1.0/pdo_oci.c: In function ‘zm_shutdown_pdo_oci’:
/tmp/PDO_OCI-1.0/pdo_oci.c:111: error: ‘dvoid’ undeclared (first use in this function)
/tmp/PDO_OCI-1.0/pdo_oci.c:111: error: expected expression before ‘)’ token
make: *** [pdo_oci.lo] Error 1

Is this the error that pdo does not connect to oci library and its find these into include subfolder, so you may need to copy all the files into include folder.

[root@ravi.com PDO_OCI-1.0]# cp -f /usr/include/oracle/10.2.0.3/client64/* /tmp/PDO_OCI-1.0/include/

Now run make & make install to compile and install the module.

[root@ravi.com PDO_OCI-1.0]# make && make install

enable the pdo_oci extension with php.

[root@ravi.com PDO_OCI-1.0]# echo “extension=pdo_oci.so” > /etc/php.d/pdo_oci.ini

[root@ravi.com PDO_OCI-1.0]# php -m | grep pdo_oci

To work pdo_oci properly you have to restart apache.

Thanks

Ravi

How to install VNCSERVER on CentOS

yum groupinstall “GNOME Desktop Environment”
yum install xterm vnc-server vnc

remove the existing file & edit with ‘/etc/sysconfig/vncservers‘ and put the following lines in it

VNCSERVERS=”2:root”
VNCSERVERARGS[2]=”-geometry 800×600 -nolisten tcp -nohttpd -localhost”

set the vnc password to open the vnc for user root (you have to login as a root)
vncpasswd

set the vnc password to open the vnc for user (you have to login as a normal user that way it will create the file xstartup in $home/.vnc)
vncpasswd

Now start the vncserver as root user
/etc/init.d/vncserver start

Now kill the vncserver proocesses using ‘ps aux | grep vnc | xargs kill -9′

and start vnc server by following command
vncserver

check the given path to open the vnc display as given in example
New ‘appserver.ravi.com:3 (root)’ desktop is appserver.ravi.com:3

before open the vncviewer remove the file ‘/tmp/.X1-lock’

Now open the vnc display you will get the default ‘xterm’ open on it.

How to install GeoIP and mod_geoip2 on centos for apache

1) yum install GeoIP GeoIP-devel GeoIP-data zlib-devel

2) mkdir /usr/local/share/GeoIP

3) Download the latest Country and City database files from maxmind

cd /usr/local/share/GeoIP
wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCountry/GeoIP.dat.gz
wget http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz
gunzip GeoIP.dat.gz
gunzip GeoLiteCity.dat.gz

4) yum install httpd-devel apr-devel

5) wget http://geolite.maxmind.com/download/geoip/api/mod_geoip2/

6) tar xvzf mod_geoip2_1.2.5.tar.gz && cd mod_geoip2_1.2.5

7) apxs -i -a -L/usr/lib64 -I/usr/include -lGeoIP -c mod_geoip.c

Enabling mod-geoip
Nothing’s going to work unless mod-geoip is enabled in your apache configuration. You’ll need the following lines in your httpd.conf file (located on CentOS systems at /etc/httpd/conf/httpd.conf)

<IfModule mod_geoip.c>
GeoIPEnable On
GeoIPDBFile /usr/local/share/GeoIP/GeoIP.dat Standard
GeoIPDBFile /usr/local/share/GeoIP/GeoLiteCity.dat Standard
</IfModule>

9) Restart Apache so your changes will take effect by entering the following command.

#/etc/init.d/httpd restart

10) /usr/local/bin/geoipupdate

Dear All,

We wish you Happy new year 2010 to all of you!

Regards,

IndianGNU.org & openlsm

Introduction ~

—————————————–
Program (1) ~ array.sh
—————————————–

#!/bin/bash
echo “==============”
declare -a myarr[0]=”Arun”
declare -a myarr1
myarr1=(arun bagul bangalore mumbai raju santhosh)
myarr[1]=”Bagul”

echo “my name is ${myarr[0]} ${myarr[1]}”
echo “————————–”
echo “${myarr1[*]}”
echo ${myarr1[2]}
echo ${myarr1[@]}
echo “————————–”
echo “Total no of elements in array – ${#myarr1[*]}”
echo “Total no of elements in array – ${#myarr1[@]}”
echo “Size of word ‘${myarr1[2]}’ is – ${#myarr1[2]}”
echo ${#myarr1[1]}
echo ${#myarr1[0]}

echo “————————–”

#how to delete element in array
unset myarr[1]
echo “myarr is – ${myarr[*]}”

#how to assign element in array
myarr[1]=”- System Engineer!”
echo “myarr is – ${myarr[*]}”

echo ${myarr}

————————————————————————
Program (2) ~ command_line_arguments.sh
————————————————————————

#!/bin/bash

echo “Script/command name => $0″
echo “arg1 => $1″
echo “arg2 => $2″
echo “arg3 => $3″
echo “Total No of argument = $#”

echo “Script PID is => $$”
echo “Status of previous command – $?”

name=$myname
echo “Name – $name”

read n

————————————————-
Program (3) ~ default_value.sh
————————————————-

#!/bin/bash

#start=’123′
#start=${1:-$start}

start=${1:-’123′}

echo “Value of ’start’ variable is ==> $start”

—————————————————
Program (4) ~ echo_example.sh
—————————————————

#!/bin/bash

name=”Arun”

echo -e “My Name is $name_arun and \n”
echo -e “My Name is ${name}_arun and \n”

echo -e ‘My Name is $name and \n’

—————————————–
Program (5) ~ elif.sh
—————————————–

#! /bin/bash

if [ $1 -eq $2 ];then
echo “good”
elif [ $2 -eq $3 ];then
echo “Fine”
elif [ $1 -eq $3 ];then
echo “OK”
else
echo “NO”
fi

————————————————————
Program (6) ~ for_loop_example-1.sh
————————————————————

#!/bin/bash

i=1
while [ $i -le 512 ]
do
temp=$i
echo “What is => $i | $temp”
i=$(expr $i + 32)
for (( j=$temp; $j<=$i; j++ ))
do
echo -n ” $j”
done
done

———————————————————–
Program (7) ~ for_loop_example-2.sh
———————————————————–

#!/bin/bash
#for val in $(ls -1 /tmp)
sum=0
#for val in {1..5}
#for val in {$1..$2}
for((val=$1;$val<=$2;val++))
do
#echo “$val”
sum=$(expr $sum + $val )
#sum=`expr $sum + $val`
done

echo “$0 # Sum of $1 to $2 => $sum”

————————————————————
Program (8) ~ for_loop_example-3.sh
————————————————————

#!/bin/bash

for i in {1..9}
do
echo $i
done

—————————————–
Program (9) ~ function.sh
—————————————–

#!/bin/bash

function my_function()
{
name=”Arun Bagul”
echo “‘my_function’ body ~ $name”
return 1;
}
##########

myfunc()
{
echo “Another way of defining the function”
}

##########################

echo “Starting function program”
echo “——————————”

#calling function here
my_function
##
myfunc

echo -e “\n end of program”

—————————————————————————————
Program (10) ~ how_to_pass_argument_to_function.sh
—————————————————————————————

#!/bin/bash

function my_function()
{
echo “Total number of argument ~ $#”
echo “Arg1 => $1″
echo “Arg2 => $2″
echo “Arg3 => $3″
return 0;
}
##########

echo “Starting function program”
echo “——————————”

#calling function here
my_function arun bagul 1234

————————————————————————-
Program (11) ~ how_to_take_hidden_input.sh
————————————————————————-

#!/bin/bash

echo -n “Enter User Name :”
read username
echo -n “Enter Password :”
read -s mypwd

echo -e “\nI am $username and my password is – $mypwd”

——————————————————————————
Program (12) ~ how_to_take_input_from_user.sh
—————————————————————————–

#!/bin/bash

echo -ne “Enter the Name:- ”
read name
echo -n -e “Enter the Number:- ”
read num

echo “——————————”

add=$(expr $num + 10)

echo “Name is ~ $name”
echo “Number is ~ $add”

—————————————–
Program (13) ~ ifthen.sh
—————————————–

#!/bin/bash

if [ "arun" == "arun" ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ 2 == 2 ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ "arun" = "arun" ];then
echo “true!”
else
echo “false”
fi

echo “———————————-”

if [ 2 -eq 2 ];then
echo “true!”
else
echo “false”
fi

——————————————————
Program (14) ~ non-interactive.sh
——————————————————

#!/usr/bin/expect -f
spawn ssh arun@192.168.0.1
expect “password:”
sleep 1
send “pwd\r”
interact

—————————————————————-
Program (15) ~ read_file_line_by_line.sh
—————————————————————-

#!/bin/bash

file_name=”/etc/hosts”

while read myvar
do
echo “Line => $myvar”
done < $file_name

echo “#################################################”

for myvar1 in $(cat $file_name)
do
echo “Line => $myvar1″
done

——————————————————
Program (16) ~ reverse-number.sh
——————————————————

#!/bin/bash

declare -a date_array
num=$1
i=$(expr $(echo $num | wc -c) – 1 )

while [ $num -gt 10 ]
do
temp=$( expr $num % 10 )
num=$( expr $num / 10);
echo “Digit($i) => $temp”
date_array[$i]=”${temp}”
i=$(expr $i – 1)
done
echo “Digit($i) => $num”
date_array[$i]=”${num}”

echo ${date_array[*]}

——————————————————–
Program (17) ~ string-operation.sh
——————————————————–

#! /bin/bash

echo “Arun Bagul:-”
string=”/root/arun/bagul/image.gif”
echo “string=> $string”
echo “String=> ${string##/*/}”
echo “String=> ${string#/*/}”

echo “String=> ${string%.*}”
echo “String=> ${string%%.*}”
#str=”/home/y/conf/arunbagul/daily_market_0.conf”
str=”${str##/*conf/}”
echo “String=> ${str%/*}”

#done

mystr=”keyword_summary_exact_arunsb”
echo $mystr
echo ${mystr%_*}

echo “$*”

—————————————–
Program (18) ~ switch.sh
—————————————–

#!/bin/bash

echo ” Switch program | arg1 => $1″
echo ” ——————————-”
case $1 in

123)
echo “Case is 123″
;;

arun)
echo “Case is ‘arun’”
;;

pri*)

echo “Case is ‘pri*’”
;;

*)
echo ” * Usage: $0 ”
echo ” Default case (nothing is matched)”
exit 0;
;;
esac

—————————————————————–
Program (19) ~ while_loop_example-1.sh
——————————————————————

#!/bin/bash

mywait=wait

while [ "${mywait}" = "wait" ]
do
echo “arun”
done

——————————————————————-
Program (20) ~ while_loop_example-2.sh
——————————————————————–

#! /bin/bash

## on command line -> i=0 && while [ $i -le 10 ] ; do echo $i; i=$(expr $i + 1); done

i=0
while [ $i -le 10 ]
do
echo $i
i=$(expr $i + 1)
done

——————————————————————–

* Please download PDF file http://www.slideshare.net/arunbagul/bash-learning-by-examples/

Regards,
Arun