ServerBuddies Support Blog

tshark - Dump and analyze network traffic

TShark is a network protocol analyzer. It lets you capture packet data from a live network, or read packets from a previously saved capture file, either printing a decoded form of those packets to the standard output or writing the packets to a file. TShark’s native capture file format is libpcap format, which is also the format used by tcpdump and various other tools.

Without any options set, TShark will work much like tcpdump. It will use the pcap library to capture traffic from the first available network interface and displays a summary line on stdout for each received packet.

Example :

-n Disable network object name resolution (such as hostname, TCP and UDP port names), the -N flag might override this one.

-i [capture interface]

Tags: analyze, dump, Network, traffic, tshark

hdparm get/set SATA/ATA device parameters

Hdparm is a tool that allows you to set IDE device settings. This includes things such as DMA modes, transfer settings and various other settings that can help improve the speed of your hard disks and CDROMs. These settings are not enabled by default, so you will probably want to enable them.

Getting information about your different drives.

Different drives have different capabilities, so in order to configure them you must know what they are capable of doing. # hdparm -i /dev/hdX should give you the information you need (replace hdX with your drive)

-i Display the identification info that was obtained from the drive at boot time, if available. This is a feature of modern IDE drives, and may not be supported by older devices.

Benchmarking devices

hdparm -tT

hdparm includes a handy benchmark mode, which should allow you to see how much of a speed. When running a benchmark it is recommended that you close all programs that could interfere with the results.

You can use the following command to check what your IDE chipset

To enable DMA on a device type the following:

Now run a benchmark and see how much of an improvement you have received.

Tags: ATA device, hdparm, Parameters, SATA

Installing OpenVZ

OpenVZ is operating system-level virtualization based on a modified Linux kernel that allows a physical server to run multiple isolated instances known as containers, virtual private servers (VPS), or virtual environments (VE).

Installing OpenVZ on a CentOS 4 or CentOS 5

Download - http://download.openvz.org/openvz.repo

Import the OpenVZ key

Install the OpenVZ kernel

Depending on which kernel arch you want, simply do:

or

Reference - http://download.openvz.org/doc/OpenVZ-Users-Guide.pdf

1) Examine /etc/grub.conf to ensure the desired kernel is set to be the default,

2) Edit the /etc/sysctl.conf to enable some kernel features that are needed for OpenVZ and

3) Make sure SELINUX is disabled.

Tags: installing, OpenVZ

Optimizing the EXT3 file system on Linux

There are some things you can do to give ext3 a boost when you just want speed.

Mount Options noatime,nodiratime

noatime
Do not update inode access times on this file system (e.g, for faster access on the news spool to speed up news servers).

nodiratime
Do not update directory inode access times on this filesystem.

This is one of the quickest and easiest performance gains. This mount option tells the system not to update inode access times. This is a good option for web servers, news servers or other uses with high access file systems

Also from the man pages.

commit=nrsec
Sync all data and metadata every nrsec seconds. The default value is 5 seconds. Zero means default.

Tags: ext3, file, linux, Optimizing, System

How to fix wget for Fantastico install

If it is wget-1.10.2-3.3.fc5 or wget-1.10.2-8.fc6.1. This version does not honor the “-P” switch.

Update to the latest versino or An alternate version that we know works is wget-1.10.2-3.2.1

You will also want to put wget on /etc/yum.conf’s “exclude=” line (near the start of the file) so the OS doesn’t automatically reinstall the buggy version.

Reference - http://www.netenberg.com/