http://shahidz.com Passionate About Technology Thu, 23 Oct 2008 16:12:17 +0000 http://backend.userland.com/rss092 en Description ufw is stands for Uncomplicated Firewall, this program is for managing a Linux firewall and aims to provide an easy to use interface for the user, as well as support package integration and dynamic-detection of open ports. ufw  is not intended to provide complete firewall functionality via its command interface, ... http://shahidz.com/ufw-uncomplicated-firewall/ There is no straight forward method for 301/302 URL redirection as we did with rewrite rule. But there are some situations where we need to redirect a URL on a host to some URL on different host. In this situation we need to use 301/302 redirection.  There are two ways ... http://shahidz.com/url-redirecting-301302-in-varnish/ !-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --> Varnish is a reverse proxy or http accelerator that uses serverside caching to increase the speed of servicing HTTP requests for use in things such as websites. The varnishd daemon accepts HTTP requests from ... http://shahidz.com/varnish-configuration-and-settings/ There are a number of things that can go wrong in code and they bound to through errors, even if you've tested them hundreds of times. PHP provides some error handling methods such as error_reporting(), set_error_handler(), error_log(), restore_error_handler() for handling errors in the PHP code. error_reporting - Sets which PHP errors ... http://shahidz.com/how-to-log-or-mail-errors-in-php-code/ Introduction OpenNTPD is a Unix system daemon implementing the Network Time Protocol to synchronize the local clock of a computer system with remote NTP servers. OpenNTPD is primarily developed by Henning Brauer as part of the OpenBSD project. Its design goals include being secure (non-exploitable), easy to configure, accurate enough for most ... http://shahidz.com/how-to-synchronize-the-time-of-a-system/ Introduction httperf is a tool to measure web server  performance. Example $ httperf --server haproxy.com --port=80 --uri /frontend_dev.php --num-conns=25 httperf --client=0/1 --server=haproxy.com --port=80 --uri=/frontend_dev.php --send-buffer=4096 --recv-buffer=16384 --num-conns=25 --num-calls=1 Maximum connect burst length: 1 Total: connections 25 requests 25 replies 25 test-duration 0.528 s Connection rate: 47.4 conn/s (21.1 ms/conn, <=1 concurrent connections) Connection time [ms]: min 4.9 avg ... http://shahidz.com/website-performance-testing-using-httperf/ What is Port Forwarding? Port forwarding is a feature of the IPTables system. It allows one computer to forward connections made to it so that another computer can actually process the request. If you want a very simple metaphor you can think of it as mail forwarding. Each ... http://shahidz.com/iptables-port-forwarding-on-ubuntu/ In Linux there has a number of useful bandwidth monitoring tools such as nload, netwatch, iftop, trafshow, bandwidthd, vnstat. If all you need is a basic overview of your total bandwidth usage, iptables is all you really need. Usually we use iptables for setting firewall and port forwardings, but iptables ... http://shahidz.com/bandwidth-monitoring-using-iptables/ Logrotate Log files are important for Linux system security and trouble shooting.  Log files tend to grow, and if a log grows too much you compress it and takes the backup. Logrotate enables you to do this in a much better way. The process that is in charge of compressing and ... http://shahidz.com/logrotate-in-linux/ Haproxy HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications. It is particularly suited for web sites crawling under very high loads while needing persistence or Layer7 processing. Supporting tens of thousands of connections is clearly realistic with todays ... http://shahidz.com/apache-load-balance-using-haproxy/