IPsec, Racoon, setkey, Linux, Mikrotik, tunnel, transport and everything

It took me more than 6 months in order to sort all issues, so here are the experiences. Most of the trouble was because I didn’t knew or I didn’t had things clear in my mind. I wanted to have IPsec communication between a bunch of servers and a home network. I believe that this …

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rsync as root with rrsync and sudo

Here’s how to rsync something to a remote host as root without allowing root logins and with directory restriction. I did that because I wanted to sync /srv across servers. In general it will use rsync over ssh, sudo, rrsync and a remote non-root user. I assume that rsync will run from srv1 to srv2. …

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Linux Containers: Easy LXC

Linux containers (a.k.a. LXC) rock. It’s the ultimate way of having multiple Linux boxes with minimal requirements. Here’s how I do it under Debian (and the script I’m using): Requirements This guide is for Debian  testing as of 25 March 2012. However it should work for other cases as well. The procedure creates a minimal …

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Quick fix for X.org screensaver bypass

This vulnerability is quite annoying if you’re locking your desktop in work or anywhere else. In short, one is able to kill xorg’s xscreensaver’s lock by just pressing alt-ctrl-* or alt-ctrl-/ (both * and / need to be from the keypad). A workaround that was posted suggests to modify files in the system. If you …

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fix for radeon + opensource driver + kde effects = crash

The problem Kwin crashes when enabling opengl effects. It doesn’t crash immediately but it crashes after specific actions so it is 100% reproducible. For example when exiting from desktop-grid effect. The situation I’m using: Radeon 4870 graphics card (RV770) Kernel 3.1.5 (but seems irrelevant) Open source ATI driver with KMS using Gallium Xorg 1.11.2.902 (but …

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Big nfs_inode_cache

The story Boxes with various kernel versions have weird free memory problems. After examining the memory usage it seems that processes don’t add up to the actual memory that is being used. Taking a look at /proc/meminfo we see something like this: Notice that Slab is about 7.5GB, almost the whole memory (8GB) (!). Slab …

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Multiple Monitors with Opensource Radeon Driver and Xorg

Setting up multiple monitors is currently a nice experience. Doing this from krandrtray, which is a very very nice front-end, is easy. But doing it via xorg.conf can be … well … interesting. That’s mostly because each driver has its own method of properly setting up multiple monitors. Here’s how to setup multiple monitors with …

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Linux ethernet driver ring buffer

While performing some tests with a congested 10Mbps link, a strange thing happened: The link was congested only on one direction and both endpoint queues were RED queues. Based on the parameters and the queue size, the delay between those two links should be something near 170ms. However, the delay was much larger: >300ms (!). …

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Problems that went away when I switched from fglrx to opensource driver (radeon+kms+2.6.33)

For a long time ago, a computer connected to the Internet had an RV770 ATI card and used to use the proprietary fglrx driver. Yes… That was my pc… Then the latest fglrx (10.2) wasn’t compatible with the latest kernel (2.6.33) and that kernel supported Kernel Mode Setting (KMS) using the radeon driver. Debian also …

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