Kernel dropped packet analysis

2017-02-27 1 min read Fedora Learning Linux

Found a simple method to check for all the packets dropped by kernel.

First you need to install dropwatch with

dnf install dropwatch

and details of the package

Name        : dropwatch

Arch        : x86_64

Epoch       : 0

Version     : 1.4

Release     : 13.fc24

Size        : 27 k

Repo        : fedora

Summary     : Kernel dropped packet monitor

URL         : http://fedorahosted.org/dropwatch

License     : GPLv2+

Description : dropwatch is an utility to interface to the kernel to monitor for dropped

network packets.

Get kernel function name from kernel address.

2017-02-13 1 min read Learning

If you are using pmap or using strace and want to covert kernel address to function name then you can use the following technique.

First you need to install elfutils, if not installed.

dnf install elfutils

and after this you can use the following command

eu-addr2line -f -e /boot/vmlinuz-$(uname -r) <addr>
#Example
eu-addr2line -f -e /boot/vmlinuz-$(uname -r) 00007f36a8045000

Separation Anxiety: A Tutorial for Isolating Your System with Linux Namespaces

2017-02-06 18 min read GuestPost Linux Vurtualization

With the advent of tools like Docker, Linux Containers, and others, it has become super easy to isolate Linux processes into their own little system environments. This makes it possible to run a whole range of applications on a single real Linux machine and ensure no two of them can interfere with each other, without having to resort to using virtual machines. These tools have been a huge boon to PaaS providers. But what exactly happens under the hood?

journalctl command to see kernel messages

2017-01-30 1 min read Fedora

Sometimes, there are just too many messages in journalctl output and it becomes a mystery game to search for the messages you are looking for. But luckily you do not need to use grep to find the right message. Here is example of what I had to do when I was looking for kernel messages.

journalctl _TRANSPORT=kernel
# To see all the fields, you can use the verbose mode
journalctl _TRANSPORT=kernel -o verbose

# And the filter on priority if needed to get the messages you need
journalctl _TRANSPORT=kernel PRIORITY=4

# and follow
journalctl _TRANSPORT=kernel PRIORITY=4 -f -l

tora installation on Fedora 17.

2012-06-22 1 min read Database Fedora

Here are the previous links on Tora:

Tora on F16

Tora on Fedora

And if you are interested in installing from source then you can always use this link:
http://blog.amit-agarwal.com/2012/02/06/tora-fedora-16-mysql-oracle/

And if you are interested in just installing it then you can always do:

rpm -ivh "http://amit-agarwal.co.in/mystuff/tora-2.1.3-1.fc17.i686.rpm"

Upgrade to Fedora 17 from 16.(amit-agarwal.co.in)
Fedora 17 warning: kernel panic after upgrade (part 2)(kparal.wordpress.com)
Fix Fedora 17 Kernel Panic after Preupgrade(loviniltra.com)

Short Information about loaded kernel modules

2010-01-24 2 min read Linux

There are couple of ways you can find the information on the <a class="zem_slink" title="Loadable kernel module" rel="wikipedia" href="http://en.wikipedia.org/wiki/Loadable_kernel_module">loadable kernel modules. All these would always involve calling <a class="zem_slink" title="Lsmod" rel="wikipedia" href="http://en.wikipedia.org/wiki/Lsmod">lsmod to get the loaded kernel modules and then calling modinfo to get the info on the loaded modules. I will show you with examples:

$ lsmod
Module                  Size Used by
cdc_acm                19616 0
vfat                    8744 9
fat                    41836 1 vfat
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