Free Linux Tutorials

1. Wonder why you can’t send email from your linux server?

2. Is your mail server or 3rd party email hosting provider requires authentication for your outgoing server to send out emails successfully?

3. Are you using a default sendmail email client on your linux box and wonder why your getting maillog errors such as this:

——-sample sendmail maillog error from my nagios server—————
Oct  2 17:03:54 nms sendmail[25657]: n9293qiw025655: to=<nagios@freelinuxtutorials.com>,

ctladdr=<root@nms.freelinuxtutorials.com> (0/0), dela0928, relay=smtp.freelinuxtutorials.com.

[216.200.145.17], dsn=5.1.1, stat=User unknown
Oct  2 17:03:54 nms sendmail[25657]: n9293qiw025655: n9293siw025657: DSN: User unknown
Oct  2 17:03:54 nms sendmail[25657]: n9293siw025657: to=<root@nms.freelinuxtutorials.com>,

For those who uses java server pages via Tomcat server on Linux, providing secure transaction on your website thru SSL protocol is a must.  By this of course  we need to install a CA assigned certificate on the server.

The procedure below is a sample installation of  SSL certificate which tested working on my site .

Prerequisites:

Linux (tested on CentOS 4.3 x64 and later)
OpenSSL
JDK 1.5 ( J2SE 1.5.09 at the time of this writing)
Tomcat server (Apache Tomcat 5.5.20 binary version for linux)

SETUP

1.    Linux
It is assumed that CentOS is ready and updated before installation of other packages.