Systems Administration

Remove proxy headers in Squid

August 20, 2015 Systems Administration 7 comments

Squid proxy and cache server guide

Very often we use the proxy servers to increase our privacy. By using a proxy, we can hide our own IP and present the proxy IP to other computers. However, the proxy servers often add HTTP headers informing about proxy usage, that can reveal your IP. In this article I will show how to remove proxy headers in Squid, a popular proxy server.

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Squid multiple IPs configuration

August 19, 2015 Systems Administration 7 comments

Squid proxy and cache server guide

Last time at work our system administrator had an issue with Squid multiple IPs configuration. The IP binding wasn’t working properly for him. Clients could connect to multiple IPs of the Squid server, but still all outgoing connections were made from the main IP of the server. The intention was to make Squid multiple IPs configuration that sets the IP for outgoing connections the same as the IP used to connect with the Squid server.

I have investigated the issue and, thankfully, the solution for this Squid multiple IPs setup is quick and easy. It can be simply configured by creating an ACL matching the IP used to connect with the Squid proxy, and then by using this ACL together with tcp_outgoing_address setting.

Further in the article you will find an example and working code that solves Squid multiple IPs problem.

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TinyProxy: Waiting servers (0) is less than MinSpareServers (1)

August 19, 2015 Systems Administration No comments

TinyProxy

TinyProxy users may encounter a notice similar to the following in their logs:

NOTICE    Aug 18 10:34:00 [8368]: Waiting servers (0) is less than MinSpareServers (1). Creating new child.

That problem can cause TinyProxy to work extremely slow. You can find a solution to this problem in the further part of the article. (more…)

XenServer: Local ISO storage on a new partition

February 17, 2015 Systems Administration 16 comments

Citrix XenServer

XenServer comes by default with very low available space. This creates a problem when you have an ISO file that is bigger than currently available space. Today I ran to this problem and after some tinkering I found the solution. I created on my XenServer local ISO storage on a new partition.

To get my ISO available for the new VM installations I had to find some free space for it. I had no NFSes on the network or any other network storages. Creating an NFS inside the host as a new VM (as I found on Google) was not an option for me. Which came to my mind is to simply create a new partition on the server’s hard drive and simply create a new ISO repository on it.

Here is how I did it. (more…)

Proprietary nVidia drivers under Ubuntu/Mint

October 26, 2014 Systems Administration 2 comments ,

Server Administration and Linux Tipps & Tricks

The problem

If you have troubles with getting proprietary nVidia drivers working in Ubuntu / Linux Mint, you may want to try this solution.

nVidia drivers under Ubuntu/Mint often collide with Nouveau drivers. In such situation the Nouveau drivers are getting loaded, not the proprietary nVidia ones. What you need to do, is to install propretiary nVidia drivers and block loading of the Nouveau drivers. (more…)

How to fix RTL8192cu driver

October 26, 2014 Systems Administration 69 comments

Server Administration and Linux Tipps & Tricks

Infamous RTL8192cu

RTL8192cu fix Linux wifiRTL8192cu is known to cause troubles with wifi for Linux users. The solution is to use original Realtek’s drivers but those are known to have issues with compilation on newer kernel versions (“some warnings being treated as errors” messages). Here is a quick guide how to compile the fixed RTL8192cu for new kernels.

With those instructions I successfully compiled RTL8192cu and got it working under kernel 3.13.02. Commenters and Reddit users reported that they got it working on various 3.x and 4.x kernels as well.

Other problems that this instruction solves:

  • RTL8192cu Linux 3.1
  • RTL8192cu Linux 4
  • compiling RTL8192cu
  • 0df6:0070 drivers
  • rtl8192cu some warnings being treated as errors

 

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Xinerama moving windows problem

October 20, 2014 Systems Administration 3 comments

Server Administration and Linux Tipps & Tricks

Xinerama moving windows problemAre you a Xinerama user, who runs regularly into a Xinerama moving windows problem like this one on the left?

It’s your lucky day. You have finally found the solution for that damned bug in Xinerama!

I couldn’t find the answer anywhere before. As I have finally fixed it, I am going to share the solution for the other fellow Xinerama users.

I used Xinerama moving windows problem phrase so many times for SEO purposes. It will make people looking for fixing that problem find this website.

I have found this Xinerama moving windows problem happens when you have incorrectly set screen order in your /etc/X11/xorg.conf file. The windows are starting to jump on other monitors when you, for example, try to move a window from screen 1 to screen 3. Not all windows behave like this, but there is software that does it all the time (NetBeans is an example).

To fix and set the screen order properly (which fixes the Xinerama moving windows problem), you need to set screen IDs using a proper order. To achieve that, you need to order the monitors in your xorg.conf file starting from monitor most to the left, ending on monitor most to the right. If you have a multi-level monitors setup as I have, start by numbering left-to-right monitors on top, then continue left-to-right for monitors on bottom.

How to set the screens and identify monitors in xorg.conf file? (more…)

Block IP on your server (using iptables)

October 1, 2014 Systems Administration 1 comment

Server Administration and Linux Tipps & Tricks

In this short tutorial you will learn how to block an IP using iptables on your server. (more…)

Custom bash commands (aliases)

September 30, 2014 Systems Administration No comments

Server Administration and Linux Tipps & Tricks

Did you know how simply you can create “custom commands” in Bash, by using alias?

In Bash, alias creates a custom command that executed your predefined code. This predefined code can be, for example, an ssh command specifying IP adress, port number, login name and private key path. Instead of typing the entire long command (with possibly looking for the IP address in your notes), you can create a simple alias.

Here is an example how an alias can be used in the scenario described above: (more…)