Andrey Mikhalchuk’s Blog

Many people are dreaming about consolidating all media files (video, music, pictures etc) in a single place. For some it is a huge full of DVDs, CDs and photos. Others buy hardware media servers and store all files in them. I chose a solution based on Archos 605 WiFi and a Linux Server running UPnP Media Server. Here’s how it works …

Last 12 months I was working on an interesting device that provides the network security features many companies and families are dreaming about. You probably already have heard about different threats out there like internet predators, viruses, spyware, dangerous websites, confidential information leaking from your business and others. Also you probably tried to find answers to questions like

• Is my office network used appropriately? Do people really use it for work and not something else?
• Are my kids safe in the Internet? Are their virtual friends really friends?
• Why is my internet so slow?
• Who in my network is using the internet most, when and what for?
• How can I prevent my children or employees from browsing inappropriate content, wasting time in chats or games?

Finally, you might want to get answers to the questions immediately and you don’t want to spend a lot of time configuring every single computer in your network, installing software and other techi stuff … So the answer to all those questions is one small box called MineStream Defender and here is what it can do …

You ran ./configure and got “configure: error: C++ compiler cannot create executables”. Here is how to fix it …

I was recently installing squid at home as a single caching proxy for all computers in my home network. The simple way is just running squid on your linux router as is and configuring every single browser on all computers in your network so they access internet using squid. That’s doable, but boring. The more interesting way is setting up transparent proxy so all your http traffic goes through squid automatically. I’m not going to explain how to setup the transparent proxy as there are tons of articles in the internet about that, for instance:

• http://www.cyberciti.biz/tips/linux-setup-transparent-proxy-squid-howto.html
• http://tldp.org/HOWTO/TransparentProxy.html
• http://www.deckle.co.za/squid-users-guide/Transparent_Caching/Proxy

The documentation is very straightforward, and has just one problem: it is outdated and doesn’t work with the most recent versions of squid. I’ve read several instructions and was always ending up with these error messages:

Here’s how to fix the problem …

Unfortunately most servos you can get for a reasonable price are not the same. Each servo has its own parameters and the cheapest ones for not allow adjustments. Fortunately in the “routerbot OS” your can easily fix that problem. Here is how you can do that in the “routerbot” project.

Ufff… the most critical part of your robot project is done. Now it is time to do basic tests and assemble whatever you have done. Here’s is hwo you do that…

Linksys WRT54GL original operating system was not designed to control external devices, so we need to rewrite it with something more suitable. This post explaines how to do this and provides the new firmware. You may also want to refer to the overall project outline.

WRT54GL router is not capable of controlling mechanical parts as is. So we need to add a communication port to it. This post describes how to do that. The complete outline of the routerbot project can be found in this post.

Linksys WRT54G router and similar are very famous because of great modifications potential hidden in the device. For some purposes you may want to add a serial port to the router. You may need that for development purposes or to turn the router into a robot for instance. This post describes the procedure of taking the router apart so you can get access to the serial port connector hidden inside.

For our robot we will need the following parts and tools:

Somehow my kids became huge fans of different kinds of robots, starting from teleoperated planet explorers and ending with transformers. So I promised them to build a robot, and in a few days I ended up with this result which I’m pretty proud to share. It appeared that for $150 or less you can build pretty cool robot that is way easier to program then most robots out there on the market + its range is way larger then most toys have. Here’s how you can build your own inexpensive yet powerful robot…

Imagine you need to create say 10 disks with predefined partitions loaded with some software. The ideal solution would be automatic disk partitioning and copying the software to it. While copying files is an easy-to-do everyday procedure partitioning is a bit more tricky (really, just a little bit). Here is a quick trick that will allow you to partition disks quickly.

Imagine you’re repartitioning a disk and when you quit fdisk writing the new partition table automount tries to mount new partitions. So instead of refreshed disk ready for newfs you get this warning:


WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table.
The new table will be used at the next boot.


So you can forget about newfs for awhile. What do you do? Just reboot? What if you need to repartition more then one disk? Here is the solution …

Uff that was tough one … If you decided to make your mail communications more secure you probably switched on SSL option in your mail client for POP3/IMAP/SMTP servers. There is a good chance you will get one of those errors that sound like

The server you are connected to is using a security certificare that could not be verified.
A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider.
Do you want to continue using this server?

I spent way too much time solving the problem because what was just annoying message in Outlook appeared to be serious problem in MacMail. It was not capable of working correctly with that problem. In addition to that I tried to solve the problem using Plesk 8.2 that was a mistake. It appeared that whatever you do with certificates in Plesk that doesn’t affect the mail. So here is the solution for the problem:

I recently tried to calculate md5 from *nix using md5sum and PHP md5() function. The result might surprise you - they don’t match in the situation you expect them to match. Here is explanation why and how to fix that.

As usually there might be a lot of reasons for that. In my case the reason became clear when I checked /var/log/messages:
imapd-ssl: /etc/courier-imap/shared/index: No such file or directory problem. The quick and dirty solution appeared to be really quick.

The purpose of this post is not to replace the original osCommerce installation manual, but to provide answers that you maight have while installing it. It is based on my own experience and might be different from yours. This post is a part of set related to installing and configuring your own store. Please read the master file here.

When I used NFS first time 15 years ago on Sun it seemed to me the top of progress. And it really was at that time. So dealing mostly with samba during last few years I forgot how actually NFS works until a few days ago when I issued standard “mount server:/directory /mnt/subdir” and tried to compile a project. The performance was HORRIBLE. So I spent some time investigating how to improve NFS performance and found this solution:

When you need to implement a DNS master/slave relationship, you obviously can go ahead and edit named config files, but when you do next change to DNS configuration using Plesk most your changes will be lost. From the other side Plesk doesn’t provide slave server configuration at all! Here is the solution that works for me on Plesk 8.2

Sometimes, for security reasons, it is useful to disable pop3 protocol on a server, leaving users with necessity of using secure pop3 protocol (i.e. in outlook they will have to check “Use SSL checkbox”, otherwise mail just won’t work). The civilized method is of course just ask people politely to make changes to their settings, but frequently people just don’t have time to do so. This tiny hack will force them to do so, otherwise their mail just won’t come.