Networking is Easy

How Network Address Translation Work (How NAT Work)

osmaniaindo@yahoo.com (Unknown) — Wed, 25 Jan 2012 00:27:00 +0700

At the present time broadband access has become commonplace and are available in many places, access the internet has become very easy and simple to do. The Internet can be accessed from home, schools, cafes and mobile handsets, and it's getting easier by the presence of a broadband router and NAT (Network Address Translation) as one of the technologies that empower them.
In computer networking, network address translation (NAT) is the process of modifying the IP address information in the IP packet headers while in transit across a traffic routing device. That means this NAT using a user in a private network will "hidden" from the Internet it self. This have some benefits, ie: Security, IP address re-use, easy configuration on the client side.
To Understand how the NAT work I share a link "How NAT Works" that may can be used by people to learn and Understand it easily.

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094831.shtml#flash

[ Tips: ] Reboot a remote Cisco router after an misconfiguration

osmaniaindo@yahoo.com (Unknown) — Wed, 27 Feb 2008 00:48:00 +0700

Human error!!! ..... it is common, even in network administration. But if this happen on the remote router or switch that do not have person/human that can physically reboot the device then it is become....disaster!!!!

So what is the option? We can use a simple and tricky way to avoid this situation.
In Cisco router we can use command reload in minutes before you do the command input. So when everything become unaccessible, the router will reboot to startup-configuration .

In my case I use 5 minutes (may be different to other) :

Cisco# reload in 5

so when my router cannot be accessed, it will reboot in 5 minutes . After that I can access it again.

Then do the configurations. You must do it 5 minutes otherwise the router will be reboot.

But if the configuration is successfully done, do not forget to cancel it with:

Cisco# reload cancel

That's all !!

Using Network Share in Windows XP

osmaniaindo@yahoo.com (Unknown) — Wed, 27 Feb 2008 00:14:00 +0700

Do you have to connect to different folder in remote Windows XP share folder with different rights? For example, I sometimes need to copy a file to share folder "NOC" and after that I need to copy another file to share folder "ITDEPT".

Both of them located in remote windows computer that has different login and password for each (since this NOC and ITDEPT has different members). FYI the setting of rights of those folder in the remote server will be not provided here, but it it must be have read and write rights both on those folders with different logins. For this kind situation we can use below step:

For example in remote windows share you login as user "noc" with its password and will be directed to folder NOC automatically. Use this command from command prompt:

net use m: \\remotefileserver\NOC /user:Accounts\NOC

or you can use windows explorer to browse to that remote folder in the network neighborhood.
Then you copy a file to that folder. File copied succesfully.
After that you can disconnect the connection:

net use m: /delete

then reconnect to the same server with user "itdept" and its password:

net use m: \\remotefileserver\ITDEPT /user:Accounts\ITDEPT

Try to copy a file to "ITDEPT" folder. Now you can copy a file to it !!!

Just Another IM client

osmaniaindo@yahoo.com (Unknown) — Fri, 21 Dec 2007 02:37:00 +0700

Wanna try something new in Instant Messenger? I found this good site. Here you will see their comment on some alternative Instant Messenger (IM). I think this is good for ones who need to online at the same time in more thant one account in same IM services like more than one account in Yahoo Messenger.

"Tired of using the big corporate instant messengers, or just looking at what else is out there? Either way, you've come to the right place. Here is a list of some other instant messengers that are out there. Some are even compatible with the big corporate instant messengers, which means you can still talk to your friends on AIM or Msn instant messenger. Check out the Interoperability chart to find out what messengers they are compatible with."

Live CD

osmaniaindo@yahoo.com (Unknown) — Mon, 17 Dec 2007 00:50:00 +0700

This is a very good news for those who want to learn linux without effort to install or any risk lost data when install the Linux. TOday there is a site where you can download a LIVE CD and burn it to a CD/DVD. After that you can directly have linux distro in your computer without having to install the Linux to the harddisk.

Please find the site here !

Erase many files in 1 directory in UNIX/Linux

osmaniaindo@yahoo.com (Unknown) — Sun, 16 Dec 2007 19:51:00 +0700

Almost 2 months since my last posting. I have many jobs to do specially non technical made me have no time to continue spread the knowledge to others. Since today I will try to make a posting at least once a week to keep the readers update about this site.

This time I will write about "Erase many files in 1 directory in UNIX/Linux" since I got one case when the logrotate of one of my server using BSD had corrupted and I had no time to fix the logrotate package. So I made a little script and crontab-ed it like once a day in the period of minimum traffic. I use it to clean the quarantince files in qmail. Here the script
(clean-quarantine.sh):

ns1# cd /var/spool/qmailscan/quarantine/new/
ns1# ls | xargs rm

This script helped me to keep the harddrive not full when there is no logrotate process running.

Setting NTP client in Huawei Datacomm Equipment (Router, Switch, Firewall)

osmaniaindo@yahoo.com (Unknown) — Tue, 6 Nov 2007 21:27:00 +0700

At past post I showed how to setting syslog in Huawei equipments. Now I will show how to make a Huawei equipments synch their time to a centralized server using NTP protocol.
Setting the IP adddres of the NTP server (if you are using NTP server with higher stratum):

ntp-service unicast-server 10.0.10.4

or if you want to sync to other peer (with same stratum):

ntp-service unicast-peer 10.0.11.7

to make router only listen ntp from verified network (increase security), add this line:

source-interface Ethernet 1/0/6

then check the ntp synchronization using command:

display ntp-service status
display ntp-service sessions

Create PS1 in Solaris 8

osmaniaindo@yahoo.com (Unknown) — Fri, 14 Sep 2007 02:44:00 +0700

Sometime when you are already like shell environment like BASH (Bourne Again SHell), you will have problem on some old shell like csh, ksh, or even sh. In this section I will show you how to create a user and their user environment using BASH. I will use Solaris 8 as example since Solaris 8 doesnt give you BASH as your default environment.

As root , create a normal user with this command, here I will use Jackie as example

useradd -d /export/home/jackie -m -s /usr/bin/bash -c "Jackie" jackie passwd jackie

then on the /export/home/jackie/.profile add this 2 lines:

PS1="[\u@h \w]\$"
export PS1

save it. Then let the user log in using their jackie and his new password.

He will see the environment like this:
[jackie@myserver jackie]$

try to logout and login again if the result is not like expected.

Easy Syslog-ng configuration

osmaniaindo@yahoo.com (Unknown) — Fri, 14 Sep 2007 01:28:00 +0700

Syslog-ng have been the successor of the well-known Syslog which have many enhacements in features and easiness to configure. Here I will show you the basic configuration of the Syslog-ng with some examples in filter.
Although Syslog-ng is supported in Linux, Solaris, All BSD variants, AIX, HP-UX, Tru64 Unix, Irix, etc, I will only give the example in Linux only.
I assume that you already have syslog-ng installed in your machine, otherwise you can consult the vendor or distro of your Linux website or documentation.

Setting the Router, Firewall and Switches:

CISCO Router & Switch (IOS):
service timestamps log datetime localtime
no logging console
no logging monitor
logging 10.16.1.100 facility local4

HUAWEI:
info-center enable
info-center loghost 10.16.1.100 facility local4 language english

The configuration file of syslog-ng located at /etc/syslog-ng/syslog-ng.conf:

# /etc/syslog-ng/syslog-ng.conf options { long_hostnames(off); sync(0); perm(0640); stats(3600); };

source src { internal(); udp(ip("0.0.0.0") port(514)); };

## Filter for facility type or device
filter f_router { facility(local4);};
filter f_firewall { facility(local5);};
filter f_switch { facility(local6);};

## Filter for IP address
filter f_ROUTER01 { host("10.10.5.1"); };
filter f_FIREWALL01 { host("10.10.5.2"); };
filter f_FIREWALL02 { host("10.10.5.3"); }; filter f_SWITCH01 { host("10.10.5.4"); };

#Destination files
destination ROUTER01 { file("/var/log/ROUTER01.log"); };
log { source(src); filter(f_router); filter(f_ROUTER01); destination(ROUTER01); };

destination FIREWALL01 { file("/var/log/FIREWALL01.log"); };
log { source(src); filter(f_firewall); filter(f_FIREWALL01); destination(FIREWALL01); };

destination FIREWALL02 { file("/var/log/FIREWALL02.log"); };
log { source(src); filter(f_firewall); filter(f_FIREWALL02); destination(FIREWALL02); };
destination SWITCH01 { file("/var/log/SWITCH01.log"); };
log { source(src); filter(f_switch); filter(f_SWITCH01); destination(SWITCH01); };

save it, then execute these command to make the log files.

touch /var/log/ROUTER01.log
touch /var/log/FIREWALL01.log
touch /var/log/FIREWALL02.log
touch /var/log/SWITCH01.log

To START/STOP the Syslog-ng service:

service syslog start and service syslog stop or service syslog reload

try to log in to the router, and do some command like to show the cpu, then on the linux excute this command:

tail -f /var/log/ROUTER01.log

You will see some log will write to the log file.

Running Apache, MySQL and PHP in Windows

osmaniaindo@yahoo.com (Unknown) — Thu, 6 Sep 2007 01:51:00 +0700

At my early days learning NETWORKING, I did not know the difference between Linux and PHP, Server and HTML, PHP and Database and many networking terms. I just go to a local training center at my city to learn....to be a WEBMASTER.
I still did not know the meaning of webmaster ( in that time I thought it is a degree like in martial arts hehe) until the instructor said that it was a common nickname for a guy who update and maintain a website (correct me if I am wrong !).
So then I taken the wrong class to study Networking :( .
But from that day, I learns that it is very good to learn networking by web development, so I can know how the server and the process done. Since then in my spare time I asked many questions to the instructor about servers (web, mysql, ftp, dns) and also networking (IP, network operating system, etc). Thank God they very helpful to answer them.
Then to help many newbie and also Windows Lover (who do not know many things about Linux and UNIX) to create a web product using PHP, I share about an application that running on Windows (NT, 2000, XP, 2003, Vista) that also used in many Linux and UNIX OS. It is called WAMP (Windows Apache MySQL and PHP) server alias . This application use PHP 5, MySQL 5 and Apache 2 so will be updated to with the version.
With this WAMP, you can turn your Windows to be a powerful dynamic web server + database server. Just do the install and follow the manual ...and then...HOOPLA...

http://127.0.0.1/index.php status OK ...

NTP client setting in Windows 2000 and Windows XP in command prompt

osmaniaindo@yahoo.com (Unknown) — Tue, 4 Sep 2007 01:35:00 +0700

NTP stand for Network Time Protocol, which is used for Time synchronization across computer networks or equipment so the computer or equipment always has the correct and accurate time. This protocol use User Datagram Protocol (UDP) port 123. The computer or network equipment usually synchronize their local time with one or more NTP server that connect to them by LAN, WAN or Global Internet. NTP server usually get the time from an accurate time source, like GPS (Global Positioning System) or other very accurate time sources.

For some computer that run Windows XP and Vista , Linux, UNIX, Mac OS, etc, the NTP client already install default in the Operating System and have an interface to setting the NTP client. There is also some 3rd party software that can be freely to download and simple to use like TimeTools SNTP client , SP Time Sync.
But actually for Windows XP there is already some setting to use the NTP directly without use 3rd party application.

For Windows XP using GUI:
You can directly navigate START --> Control Panel --> Date and Time, klik for Internet Time, choose the time server and then klik Update Now
If success, you will see a result like this.

For Windows 2000 and Windows XP (using command):
Go to START  Run  type cmd (a command prompt will be open)
on the command prompt, type as follow, assume the NTP server is time.nist.gov or you can use your server IP address.

C:\ net time /setsntp:time.nist.gov

C:\ net stop w32time

C:\ net start w32time

Hola… you already set your Windows 2000 NTP sync without 3rd party application. Then check using this, should be no error is generated.

C:\ net time /querysntp

Good luck!!

Networking is easy

osmaniaindo@yahoo.com (Unknown) — Tue, 4 Sep 2007 00:50:00 +0700

Who said that networking is difficult, need many time to study it, need complicated configuration and need special trained person to do it? The answer is NO !! This time you and everybody else can do it easily, as you want to learn it with some efforts, a newbie like me even also can do it.
OKAY, enough with the explanations. Let us start to do it EZY-ly (easily).