Category Archives for Linux

Add Extra Security to Nginx to Stop Clickjacking & XSS protection

Clickjacking is easy to implement. There are a lot of XSS example code in the web. So any one with little understanding of WEB can attack your site with these things. We can use Nginx to stop most of the … Continue reading

15. January 2015 by Zakir Hyder
Categories: Linux, nginx | Comments

Beware of Varnish hit_for_pass

Little back story: I am very much fond of Move Fast and Break Things. I am playing with varnish last 3 months. We let go 2 programmers this month and the work load increase 2x. This should not be an … Continue reading

24. November 2014 by Zakir Hyder
Categories: Linux, Varnish | Comments

How to Recover SSh Access to Amazon EC2 Instance After UFW firewall Activation But Forgot to Allow SSH

ufw is very good tool. But if you forget to turn on ssh then you would not able to log in to your server. But you forget to enable the ssh in ec2 instance then you have a way to … Continue reading

04. October 2014 by Zakir Hyder
Categories: Linux, Ubuntu | Tags: , , , , , , | Comments

Setting Up Varnish Security Firewall

Varnish can add a extra layer of security as well as HTTP accelerator. is a Web Application Firewall (WAF) written using the Varnish Control Language (VCL) and a sprinkling of Varnish Modules (vmods). If you want to know how … Continue reading

01. October 2014 by Zakir Hyder
Categories: Ubuntu, Varnish | Tags: , , , , , , | Comments

Building a Varnish VMOD

Building a Varnish VMOD in ubuntu is bit complicated process. we are going to use varnish-3.0.5. For VMOD we are going to use Lets create a folder and get the varnish’s source code. Then we will create a make … Continue reading

28. September 2014 by Zakir Hyder
Categories: Linux, Ubuntu, Varnish | Tags: , , , , , , | Comments

Varnish BackendPolling

BackendPolling can reduce Varnish 503 errors. Varnish poll by opening a new TCP connection to the backend on which we send a preconfigured request, wait for the answer and the connection to be closed by the backend. Only if Varnish … Continue reading

16. September 2014 by Zakir Hyder
Categories: Linux, Varnish | Tags: , , , , | Comments

Be careful of MySQL Query Cache

Configuring MySQL server for high traffic site is very hard. You have to consider many things. One of the pitfall for unweary person like me is query_cache_size. I must confess I thought it would make my mysql server would perform … Continue reading

11. September 2014 by Zakir Hyder
Categories: Linux, MySql, Server Management | Tags: , , | Comments

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