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nmap usage

#1: Scan a single host or an IP address (IPv4) ### Scan a single ip address ### nmap 192.168.1.1 ## Scan a host name ### nmap server1.cyberciti.biz ## Scan a host name with more info### nmap -v server1.cyberciti.biz

Sample outputs:

Fig.01: nmap output

#2: Scan multiple IP address or subnet (IPv4) nmap 192.168.1.1 192.168.1.2 192.168.1.3 […]

fix ncurses program not working properly under putty terminal

The problem is that PuTTY in UTF-8 mode ignores1 VT100 “Alternate character set” commands, and ncurses attempts to use the “graphical” character set for drawing the GUI. (The box drawing characters are in the same positions as klmqx would normally be.)

export NCURSES_NO_UTF8_ACS=1 it should fix the problem by telling ncurses to always use Unicode […]

Increase the tx and rx buffer for vmxnet3 and e1000 virtual NIC for VMWare

To deploy a vm doing routing between virtual NIC, you may need to increase the tx and rx buffers of the NIC to cope with burst traffic.

– To show the current tx and rx buffer of your NIC

ethtool -g eth0

– To increase the tx and rx buffer to the max preset

ethtool […]

video encoding software for Linux

I found handbrake http://handbrake.fr/ was useful and easy to use on Linux

Some rethinks about today’s RAID 5

http://www.standalone-sysadmin.com/blog/2012/08/i-come-not-to-praise-raid-5/

AND

RAID’s write penalty on IOps

http://www.yellow-bricks.com/2009/12/23/iops/

Force Centos/Fedora login screen to ask for username rather than displaying a list of users

gconftool-2 –direct –config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory –type Boolean –set /apps/gdm/simple-greeter/disable_user_list True

swap_free: Bad swap file entry xxxxxxxxxxxxxx

I have entered this error on one of Linux box. Initially, I though this was caused by the harddisk problem but finally, it turned out to be a memory problem.

Password Safe with Vim and OpenSSL

Use vim with openssl to store your password encrypted in AES 256 bits, etc

A Very useful plugin for vim, I use it to store my server passwords and other secrets : http://www.noah.org/wiki/Password_Safe_with_Vim_and_OpenSSL

unixtodos in Ubuntu

apt-get install tofrodos

Use the command todos & fromdos for the conversion

TCP/IP tuning

How To: Network / TCP / UDP Tuning This is a very basic step by step description of how to improve the performance networking (TCP & UDP) on Linux 2.4+ for high-bandwidth applications. These settings are especially important for GigE links. Jump to Quick Step or All The Steps. Assumptions This howto assumes that the […]

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