webHauser Blog

Install MySQL Database version 3.23.54

#To set the root password use the following commanding changing my_password to the password you want for the root user to access MySQL.
cat /etc/my.cnf
mysqladmin -u root password "newpwd"
mysqladmin -u root -p create linksdb
mysql linksdb

shell> mysql -u root
mysql> DELETE FROM mysql.user WHERE User = '';
mysql> FLUSH PRIVILEGES;


Installation of Java 2 SDK and Jakarta Tomcat Server

cd /usr/local/src
chmod +x j2sdk-1_4_2_08-linux-i586-rpm
rpm -i j2sdk-1_4_2_08-linux-i586.rpm

# Add these lines to /etc/profile
echo JAVA_HOME=/usr/java/j2sdk1.4.2_08 >>/etc/profile
echo export JAVA_HOME >>/etc/profile

unzip jakarta-tomcat-5.0.28.zip
mv jakarta-tomcat-5.0.28 /usr/java
groupadd tomcat
useradd -g tomcat tomcat
cd /usr/java
ln -s jakarta-tomcat-5.0.28 jakarta-tomcat
chown tomcat.tomcat /usr/java/jakarta-tomcat
chown -R tomcat.tomcat /usr/java/jakarta-tomcat-5.0.28
cd jakarta-tomcat/bin
chmod +x *.sh
. startup.sh
. shutdown.sh
# Setting up ntsysv configuration for tomcat
cat >/etc/rc.d/init.d/tomcat

 …
 …
 …
EOF
chmod +x /etc/rc.d/init.d/tomcat
chkconfig –add tomcat
service tomcat start
service tomcat status
# Modify tomcat group at /etc/group
cd /home/tomcat
chmod g+w /home/tomcat

Setup OpenVPN 2.0 with LZO compression library

cd /usr/local/src
wget http://oberhumer.com/opensource/lzo/download/lzo-1.08.gz
cd lzo-1.08
./configure
make
make check
make test
make install
# export LD_LIBRARY_PATH=/usr/local/lib
cd /usr/local/src
wget http://openvpn.net/release/openvpn-2.0.tar.gz
tar xzf openvpn-2.0.tar.gz
cd openvpn-2.0
./configure
make
make install

load TUN/TAP kernel module
modprobe tun
lsmod|grep tun
./openvpn –cd /etc/openvpn –config local.conf
 
cat >>/etc/rc.d/rc.local
if [ -x /etc/rc.d/rc.openvpn ]; then
 . /etc/rc.d/rc.openvpn
fi

EOF

#
# Turning IP Forwarding on
#

echo 1>/proc/sys/net/ipv4/ip_forward ; ha 0
$ vi /etc/sysctl.conf   ; net.ipv4.ip_forward = 1

#
# Allow masquerading from LAN PC
# Save settings for next boot
#

$ iptables -t nat -A POSTROUTING -o eth1 -s 192.168.30.20 -j MASQUERADE
$ iptables-save > /etc/sysconfig/iptables


#
# RedHat Linux 9 Server
# Network Setup
#

cat >/etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
BOOTPROTO=dhcp
ONBOOT=yes
EOF

The standard JSP tags are:

• <jsp:useBean> - Allows you to put or look up a bean in the page, request, session, or application scope. (This tag is very useful for maintaining state). JavaBean instances: Recall that the JSP engine only loads a new instance of the bean if it can’t find an existing instance in scope. This means you can use a bean as a storage container that keeps track of the application’s data anywhere within its scope.
• <jsp:setProperty> - Allows you to set the property of a bean that is already defined and in scope. Use the <jsp:setProperty> tag for Bean initialization.
• <jsp:getProperty> - Takes the value of a bean’s property, converts it to a string, and places it in the output stream.
• <jsp:param> – Provides parameters and values to the include, forward, and plugin standard actions.
• <jsp:include> – Includes a page at request time instead of translation time with the @include directive.
• <jsp:forward> – Forwards the request to another resource in the existing Web application.
• <jsp:plugin> – Enables the JSP author to generate HTML using client-browser independent constructs that result in the download and subsequent execution of the specified applet or component (results of the evaluated tag are typically replaced by an <object> or <embed> tag).

There are certain implicit variables available to a JSP:

• request – reference to the HttpServletRequest
• response – reference to the HttpServletResponse
• pageContext – provides access to the namespaces within the JSP
• session – reference to the HttpSession
• application – reference to the ServletContext
• config – reference to the ServletConfig
• page – reference to the current instance of the JSP being accessed; analogous to using this in the generated Servlet for this JSP
• exception – reference to the uncaught exception thrown by a JSP; only available on JSPs with the isErrorPage set to true

The String class represents character strings. All string literals in Java
programs, such as “abc”, are implemented as instances of this class. Strings are
constant; their values cannot be changed after they are created. String buffers
support mutable strings. Because String objects are immutable they can be
shared.

For example:

     String str = "abc";

 is equivalent to:

     char data[] = {'a', 'b', 'c'};
     String str = new String(data);

 Here are some more examples of how strings can be used:

     System.out.println("abc");
     String cde = "cde";
     System.out.println("abc" + cde);
     String c = "abc".substring(2,3);
     String d = cde.substring(1, 2);


A JSP oldalak (Java Server Pages) kiterjesztései a java servleteknek amelyek általános kiterjesztései a Java alapon működő webkiszolgáló számítógépeknek. A Java servletek webes környezetben tulajdonképpen a hagyományos CGI technológiát helyettesítik. A
servlet egy webszerver kérelemre dinamikusan betöltődő modul, amely szerver
oldalon, teljesen a Java Virtuális gép belsejében fut le.


#!/bin/bash

# Allow OpenVPN Port and VLAN tunnel
$IPTABLES -A INPUT -p udp --destination-port 1194 -m state --state NEW -j ACCEPT
$IPTABLES -A INPUT -p tcp --destination-port 1194 -m state --state NEW -j ACCEPT
$IPTABLES -A INPUT -i tun+ -p udp -m state --state NEW -j ACCEPT
$IPTABLES -A INPUT -i tun+ -p tcp -m state --state NEW -j ACCEPT
/sbin/iptables-save > /root/iptables-new