0 Setup ntpdate to run hourly

Create the myntpdate under /etc/cron.hourly. In side the file, contains ntpdate command :

ntpdate sgc

The file also needs to be executable.

chmod 755 myntpdate

The cron job log is at /var/log/cron

0 Lastlog size is huge ….

/var/lastlog show the huge size from ls output.

This does not make sense because df only show used size last than 1G

It turns out, the du would give more accurate size.

It is because the lastlog file is sparse file, it contain many empty space . Using –s option in the ls would show the actual size instead of pre allocated size. 

0 CrypTool

Very useful open source application that can help visualize cryptography … I wish I know this years ago when I still in school .

Download from here 

Pretty cool

2 Setup Replication for Mongo DB on Windows

Here are some notes for setting up the replication in Mongo DB. Unlike other DBMS, mongodb’s replication more like the database mirroring . You can  not pick or choice what column get replicate .

 

prerequisite

Configure three Mongo DB run as service. Below are my configure file.

There files are identical except the service name and port number. I use port 27017, 27018 and 27019. The key thing here is the replSet. This is the replication set name. 

MongoDB1

dbpath=D:\mongoDB\data\mongo1

logpath=D:\mongoDB\DBAREPORT\mongo1-server.log

logappend=true

verbose=vvvvv

directoryperdb=true

journal=true

bind_ip=127.0.0.1

port=27017

serviceDescription=mongo1

serviceDisplayName=mongo1

serviceName=mongo1

replSet=mongorep

MongoDB1

dbpath=D:\mongoDB\data\mongo2

logpath=D:\mongoDB\DBAREPORT\mongo2-server.log

logappend=true

verbose=vvvvv

directoryperdb=true

journal=true

bind_ip=127.0.0.1

port=27018

serviceDescription=mongo2

serviceDisplayName=mongo2

serviceName=mongo2

replSet=mongorep

MongoDB3

dbpath=D:\mongoDB\data\mongo3

logpath=D:\mongoDB\DBAREPORT\mongo3-server.log

logappend=true

verbose=vvvvv

directoryperdb=true

journal=true

bind_ip=127.0.0.1

port=27019

serviceDescription=mongo3

serviceDisplayName=mongo3

serviceName=mongo3

replSet=mongorep

From procexp, you can see three service are using the same binary but of course, they all have its own database directory.

2 Install Mongo DB on Windows

Install Mongo DB on windows is easy . 4 steps and you are in business.

• Download the software.
• Unzip the software
• Create the data folder
• run the daemon mongod.exe .

Simply control + C would shutdown the mongo DB gracefully.

---

RUN mongo DB as windows service

Create the configuration file:

dbpath=D:\mongoDB\data\mongo1

logpath=D:\mongoDB\DBAREPORT\mongo1-server.log

logappend=true

verbose=vvvvv

directoryperdb=true

journal=true

bind_ip=127.0.0.1

port=27017

serviceDescription=mongo1

serviceDisplayName=mongo1

serviceName=mongo1

• options are case sensitive . The best way to find the options are check the mongod –help
• quote on the path does not work. EX: can not use “C:\data\db”

Use below command to install as service .

mongod.exe --install --config D:\mongoDB\DBACONFIG\mongodb1.conf

Then we can find mongo db list in the service manager.

 

Errors

Failed to connect to 127.0.0.1:27017, reason: errno:10061 No connection could be made because the target machine actively refused it. 

This is because the you are running on the non-privilege session. change to the administrator command line would resolve this. 

 

 

Reference

http://docs.mongodb.org/manual/reference/configuration-options/

5 Centos 6.5 join Windows Domain and Kerberos authentication

This is my note for configure Linux intergrade windows domain authentication with Kerberos

 

Package Require

• yum install samba
• yum install krb5-server
• yum install krb5-workstation
• yum install samba-winbind
• yum install ntpdate    --> This is required for sync time
• yum install cifs-utils

 

Setup the Host Name on Linux

Setup the host name in /etc/sysconfig/network

0 tmux

tmux is terminal multiplexer. Similar to the screen that I use at office.

Here are few advantages/reasons that using tmux over screen.

• tmux is under activity development and with BSD license.
• tmux use less resource.
• Flexible control the pane.
• Scroll back history

---

Installation

It is not part of centos yum repository. To install it, we need to set up the EPEL.

yum install tmux

CONFIG:

The user configure tmux configure file is located at ~/.tmux.conf

Here is my binding and below cheat sheet is base on that.

# Lower escape timing from 500ms to 50ms for quicker response to scroll-buffer access.

set -s escape-time 50

# use UTF8

set -g utf8

set-window-option -g utf8 on

# set scrollback history to 100000 (100k)

set -g history-limit 100000

# Use something easier to type as the prefix.

set -g prefix C-x

unbind C-b

bind C-x send-prefix

# reload config without killing server

bind r source-file ~/.tmux.conf \; display-message "Config reloaded..."

# Enable auto renaming

setw -g automatic-rename on

# rebind the spilt keys

unbind %

bind \ split-window -h

bind - split-window -v

# Pane setting

bind -n F9 resizep -U 1

bind -n F10 resizep -D 1

bind -n F11 resizep -L 1

bind -n F12 resizep -R 1

set-option -g pane-border-fg green

set-option -g pane-border-bg black

set-option -g pane-active-border-fg green

set-option -g pane-active-border-bg yellow

# pane movement

bind-key j command-prompt -p "join pane from:"  "join-pane -s '%%'"

bind-key s command-prompt -p "send pane to:"  "join-pane -t '%%'"

# 256 colors please

set -g default-terminal "screen-256color"

# colorize messages in the command line

set-option -g message-bg black

set-option -g message-fg brightred

# set color for status bar, use prefix + : to enter status command bar

set-option -g status-bg black

set-option -g status-fg yellow #yellow

set-option -g status-attr dim

# set window list colors - cyan for inactive

set-window-option -g window-status-fg cyan

set-window-option -g window-status-bg black

set-window-option -g window-status-attr dim

# set window list colors - Blue for active

setw -g window-status-current-format '#[bg=red,fg=cyan,bold](#I:#F#W)'

setw window-status-current-attr underscore

# Fix putty/pietty function key problem

#set -g terminal-overrides "xterm*:kf1=\e[11~:kf2=\e[12~:kf3=\e[13~:kf4=\e[14~:kf5=\e[15~:kf6=\e[17~:kf7=\e[18~:kf8=\e[19~"

# set the status bar message

set -g status-left ' #[bold]#H ⣿'

set -g status-right '#[bold]#(whoami)  ⡇ #(uptime|cut -d "," -f 4-) ⡇ #[fg=green]%D-%H:%M#[default] '

# Activity

setw -g monitor-activity on

set -g visual-activity on

#

# Mouse Behivor

#

# allow mouse to select which pane to use

set -g mouse-select-pane on

# Allow mouse to select windows

set -g mouse-select-window on

set-option -g mouse-resize-pane on

set-option -g mouse-select-window on

# mouse scroll in tmux -> also go to the copy mode

set -g mode-mouse on

set-window-option -g mode-keys vi

unbind [

bind Escape copy-mode

unbind p

# This allow copy vmux buffer to the vi

bind p paste-buffer

bind-key -t vi-copy 'v' begin-selection

bind-key -t vi-copy 'y' copy-selection

# buffer

bind Space choose-buffer

 

 

Cheat sheet

List tmux session	tmux lis
Attached the session	tmux a –t <session id>
Kill the current window	prefix + &
pane to window	prefix + !
next pane	prefix + o
next window	prefix + n
copy mode	prefix + <ESC>
copy to the vmux buffer	use mouse select the text  or copy mode –> prefix + v to select the text –> prefix + y to copy
copy to vi	prefix + p
copy from putty to notepad	shift key and select as normally putty

putty

This is tricky one. I use putty to my linux box and I like the putty function that can just select the text and copy paste. However, because tumx buffer is independent outside the system buffer and tmux would also take the signal about the putty for the mouse resize. To achieve this goal, we have 2 ways to do it.

1. complete disable the signals from putty .

Terminal –> Features –> Disable xterm-style mouse reporting

By check this box, we can no longer use mouse to resize or pane or enter the copy mode, and copy tmux buffer.

2. Press shift key while copy paste

I decided to use the 2nd approach It will take some time to get used to it.

Another challenge is to copy the content of pane into notepad. At this point, I will just move the pane into its own window and use the shift key to do it.

 

 

reference

• https://wiki.archlinux.org/index.php/tmux
• https://gist.github.com/andreyvit/2921703

1 Install EPEL on Centos 6.5

EPEL is Fedora Repository. By default, the Centos does not configure to use it.

Below command list what is current yum repository.

yum repolist

To install it:

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
 rpm -Uvh epel-release-6-8.noarch.rpm

 

Re run the yum repolist again, this will update the repository.

 

 

Reference

 http://www.rackspace.com/knowledge_center/article/installing-rhel-epel-repo-on-centos-5x-or-6x