Aug 232014
 

KernelPanic Luckily this problem don’t happen so frequently, at least using stable kernel and distributions, but sometime your beloved Linux could go in “Kernel Panic”.

A kernel panic is an action taken by an operating system upon detecting an internal fatal error from which it cannot safely recover. The term is largely specific to Unix and Unix-like systems; for Microsoft Windows operating systems the equivalent term is “stop error” (or, colloquially BSOD “Blue Screen of Death”).

The kernel routines that handle panics, known as panic() in AT&T-derived and BSD Unix source code, are generally designed to output an error message to the console, dump an image of kernel memory to disk for post-mortem debugging and then either wait for the system to be manually rebooted, or initiate an automatic reboot.

Wikipedia

The default it’s to wait, so if this happen on one of your servers and you don’t notice it all its services could stay down for some time, while using an automatic reboot the problem could be solved quickly.

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Mar 272014
 

Small and at the same time great article from Steve on http://www.debian-administration.org/.

If you run a multi-user system it can increase security if you hide the display of running processes, and their arguments, which belong to other users. This helps avoid problems if users enter passwords on the command-line, and similar.

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Jul 112013
 

On server it’s useful to monitor, and collect, data about the use of your bandwidth, in the past I’ve wrote an article about “Monitor your bandwidth from the Linux shell” and I’ve also presented 4 useful tools that you can use to have a real time monitoring of the bandwidth:

IPTState : This software is a top-like interface to your netfilter connection-tracking table. Using iptstate you interactively watch where traffic crossing your netfilter/iptables firewall is going, sort by various criteria, limit the view by various criteria. But it doesn’t stop there: as of version 2.2.0 you can even delete states from the table!

pktstat displays a real-time list of active connections seen on a network interface, and how much bandwidth is being used. Partially decodes HTTP and FTP protocols to show what filename is being transferred. X11 application names are also shown.

NetHogs is a small ‘net top’ tool. Instead of breaking the traffic down per protocol or per subnet, like most tools do, it groups bandwidth by process. NetHogs does not rely on a special kernel module to be loaded. If there’s suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this. This makes it easy to indentify programs that have gone wild and are suddenly taking up your bandwidth.

IPTraf is a console-based network statistics utility for Linux. It gathers a variety of figures such as TCP connection packet and byte counts, interface statistics and activity indicators, TCP/UDP traffic breakdowns, and LAN station packet and byte counts.

They are all good I suggest to read my old articles to have a small introduction about them, today I want to show you vnstat, this small program has something more than the others, it can show real time statistics, but the feature that this small program shines it’s its ability to collect data over a long period of time.
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