Think shell

In one of my previous post I made a tutorial how to bypass corporate firewalls and gain access into your office computer. It work well if you are at your home and you need ssh access (or any other service) to your office computer. However if the situation is reversed, and you need to access some outside service which your firewall is blocking then you would use this little tutorial with explanations. Although all this is covered in the ssh man pages, one always learn best by real life examples, so here I’ll try to cover few of them. So to better explain our first problem look at the picture below:

The first problem

We are located at office computer which is behind the very restrictive firewall and we want to get to the non-standard service running on the remote server.

So normally if I use for example Mysql Administrator to connect on my MySql database on a remote server, that communication would happen on port 3306, and for this to work Mysql Administrator must have appropriate rules set in our firewall to allow that traffic. But what if traffic on that port is blocked?
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So i decided to make a little different post than usual, a little more thoughts based than tutorial alike.
I would like to take a brief overview of todays memory usage for various tasks and scripts. Since large part of my the day is involved in web servers and their management I will mainly focus on memory usage for web applications and scripts.

Not so long ago, having a server with 4Gb of  working memory was a luxury, today we have certain scripts consuming about 512Mb of memory while running. What changed?
Internet boom, popularity of web 2.0 applications, ease of development, bunch of those learn programing in 21 days books and tutorials, that is what happened. In addition there is a whole bunch of people from “I want Internet” generation who still don’t quite grasp the difference between RAM and Disk memory, not to mention they don’t quite grasp the inner mechanics of computer systems.

Sir… the white smoke got out of your metal box… you must refill it with white smoke to make it work again

Well, like it or not those people like to call themselves web masters and web developers.

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So recently I went nuts having to login onto each server to look at its munin graphs. While you have few servers it’s doable, but managing large farms and checking up on them while having to login into each is just pain in the ass.
So what to do?
Hey… let’s make a central munin server, and let’s hold all the graphs there. That way we can review them all with just one user name and password, we can compare host performances, etc…
To accomplish this we will need one server for centralized graphs (could be a low budget dedicated server or a small vps), apache installed on central munin server, munin-node installed on all other server we wish to monitor.
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