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Vi/Vim tips - Delete Lines

1.) Delete present line

Goto the line you want to start delete, press

Esc dd # Will delete present line

2.) Delete from line 1 to end of line.

:1,$ del # Delete from line 1 to EOL

3.) Delete from present line to end of line.

:.,$ del # Delete from present line to EOL

or

Goto the line you want to start delete, press

Esc d Shift g # Will delete all the lines from present line to EOL

. -> present line

1 -> line 1

$ -> End of Line

del -> Delete

Posted in open source | Comments

Check HTTP Latency

Install ‘echoping’ in order to check http latency.

If you are running on debian/ubuntu machine, simple run below command to install echoping:

chenhow@chenhow-laptop:~$sudo apt-get install echoping

To check latency,

chenhow@chenhow-laptop:~$echoping -v -h index.php blog.chenhow.net:80

Output:

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“.htaccess” tips and tricks

By using .htaccess files, we can control access to our web content by allowing/blocking certain user or ip address to access it.

You may ask why we need that, if you can do the same by using options like “order, limit” to restrict ipaddresses and user actions in httpd.conf.

Fair enough, but there is some limitation.

Ok, let me give you a few secarios:

Let say you are a system administrator in ABC company and your company have a few branches over the world. All these branches located in Malaysia, Singapore, Taiwan and China. And each branches will have their own web directory to store all their documents.

Each branches office have a static ip and domain name
Malaysia    1.2.3.4        www.abc.my
Singapore    2.3.4.5        www.abc.sg
Taiwan        3.4.5.6        www.abc.tw
China        4.5.6.7        www.abc.cn

So, one day..

senarios 1:
You boss came to you and ask you to restrict all the web directory, that only allow all the branches can access to it, public user shouldn’t able to view or access it.  Well, it will be easy , u just need to change the httpd.conf

httpd.conf

AllowOverride None Options AuthConfig # Allow use of the authorization directives
Order deny,allow
deny from all
allow 1.2.3.4
allow 2.3.4.5
allow 3.4.5.6
allow 4.5.6.7

But, in the same time , he wants to access all this directory from his house, which using dial up and doesnt have a fix address or ddns.

so what now?

Either you can ask him to apply a fix line or ask him to register dynamic dns.
But, ur boss definately wont like it.
so the best solution is to control the web content with valid username n passwd, another word ‘Web authentication’.

simply create a .htaccess in protect folder and add the following lines

Options  Indexes #to enable directory listing
AuthName     “Password Protected by .htaccess“ #Message that prompt when asking for username and password
Authtype     Basic
AuthUserFile /usr/local/apache2/passwd #password file location
require user boss #username boss
satisfy any #either u r using malaysia,china,singapore n taiwan ip or u have a valid username and password, then u can view and access this directory

if satisfy all, mean u must be one of the country ip and have to provide valid username n password in order to access.

generate username and password file

htpasswd -c /usr/local/apache2/passwd boss

-c is to create new passwd file, if u want to use back the existing password file

htpasswd /usr/local/apache2/passwd boss2

Is quite handy when you do not have the permission to change the httpd.conf file or restart the webserver.

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CCNA

Yesterday I saw a big letter with my name put on the kitchen table. Guess what, I finally/officially a CCNA certified engineer.

The CCNA certification kits looks really cool.

Well, now I must focus on my next certification, either RHCE/CISSP. Hard work, hard work..

Posted in Networking | Comments

How To Find duplicate IP

To find duplicate IP, you can create a text file and putting all the IP addresses into it and seperate them with line break.

eg:

Create a text file called ip.txt
[root@www ~]# touch ip.txt

Put all the ip into the file and save it
[root@www ~]# vi ip.txt

192.168.1.22
192.167.1.22
192.168.1.23
192.168.1.23
192.168.1.70
192.168.1.88
192.168.1.89
192.168.1.40
192.168.1.63
192.168.1.77
192.168.1.79
192.168.1.78
192.168.1.11
192.168.1.82
192.168.1.24
192.168.1.91
192.168.1.64
192.168.1.94
192.168.1.21
192.168.1.96
192.168.1.95
192.168.1.69
“ip.txt” 138 lines, 2138 characters

Execute below command to find the duplicate ip
[root@www ~]# sort ip.txt | uniq -d

#It will display all the duplicate IP
192.168.1.22

Posted in Ubuntu | Comments