Linux Router and Protocol Analysis

Last week, when this exercise was given, I was not able to get a partner so I decided to do it on my own using my laptop and my sister's laptop. But before I can do the exercise, I still need to install Ubuntu on both laptops. After installing Ubuntu, I tried to do the exercise but I failed.

Today, we continued doing the exercise. I joined the pair of Meeren Aguilar and Marian Bundalian. We were struggling at the beginning and were not able to connect wirelessly. We tried entering the command line "rm /etc/udev/rules.d/70-persistent-net.rules" and then rebooting the PC's but still failed connecting the computers. Thirty minutes before 7:00P.M. we were able to connect the computers and my computer, computer B was able to connect to the internet through computer A, Meeren's computer.

Screenshots below show the step by step configuration of my computer, computer A.

Figure1: Checking the ip configuration first using ifconfig.

Figure 2: Step 1 - Assign the static IP address 192.168.x.1 to the interface connected to Computer B using ifconfig.

Figure 3: Step 2 - Set the IP address of Computer B as the default gateway.

Figure 4: Step 3 - Try to ping Computer B using other IP addresses (10.0.4.42 and 10.0.4.254)

The picture shows that 10.0.4.42 was pinged successfully while 10.0.4.254 was unreachable.

Figure 5: Step 4 - Copy the contents of /etc/resolv.conf of Computer B to the /etc/resolv.conf of Computer A

Figure 6: Visit your favorite web site using your favorite web browser.

The picture above is not my favorite web site but I thought of a site which has few items to load (I'm not a person with so much patience ;D). I swear with all my heart that this is not a faker. I was really able to connect to the Internet through Meeren's compter. :)

Sad to say, this is the farthest our group has finished. We ran out of time and began saving backups of screen shots to be used for our blogs few minutes before 7:00 P.M. This exercise is more fun and less frustrating than the exercise for DNS. Because in this exercise, there's improvement but in DNS, I can't even find the error in my code. (makapag rant lang :P )

Today's topic is pretty cool even if our group only managed to finish only the first part. The idea of connecting to the Internet through another computer is amazing. Though, I'm used to creating adhoc connection in Windows because we don't have a router in our apartment. But that's easy because Windows has a user friendly function for creating adhoc connections.

Though I enjoyed this topic, I'm not satisfied because I'm the type of programmer who wants to understand what's really happening in every command line that I enter. I like it when the prof explains what's happening and enlightening the confusions I have. I really appreciate it when my prof answers the questions instead of playing hard to get when I am really lost on what to do next. I  wish I can do better in the next exercise. :)

The Frustrating DNS

Why, hello there. Today is an unlucky day for me. I missed the quiz for the second time. Ugggh. Next meeting, I'll make sure I won't be late again. >_<

Today's topic is quite confusing and frustrating. I didn't absorb the topic that much because I was too busy thinking of my "banat" for the quiz. :)) But I was able to take down some of the important notes.

Here are some definition of terms:

• DNS - Domain Name System
• NIS - Network Internet System
• WNIS - Windows Internet System
• SOA - Start Of Authority
• NS -  Name Server
• A - Hostname Adress Map
• PTR - Maps Address to Names
• MX - Mail Exchanger
• NAME - Canonical Name

The topic for today taught me a deeper idea of the Domain Name System. My knowledge in DNS is now deeper because of the hands on experience in setting up and configuring domain and subdomains. Before, I only know that domain names are just string of letters and numbers as substitutes for IP addresses. It's just a shame I wasn't able to configure the domain system in the exercise.

The screenshots below show the relevant files for configuring the domain system.

Figure 1: Source Code for name.conf.local

Figure 2: Source Code for db.cmscwantriseben.com

Figure 3: Source Code for db.192.168.3

Figure 4: Query "named-checkconf named.conf.local" Returns No Error

Figure 5: named-checkzone Query  Returns Weird Notifications

Figure 6: Source Code for resolv.conf

Figure 7: dig mra Query Return Wrong Output

Figure 8: Ping Fail

Today's topic may be hard but I know that UP does not settle for easy things and we should treat every failure a challenge. And we strive hard to make that failure a success. Even if I didn't fully grasp the topic for today, I'm now responsible to help myself learn about the topic on my own. Thank you for the effort, sir. Kahit na gustong gusto mo na kaming ifull spoon feed kanina. :))))

Another banat:

Alam mo tama lang na EX-er ang tawag sa task kanina. Kasi just like almost all of the EX-es, kahit paulit ulit mong isipin at intindihin, minsan, di mo pa rin malaman kung saan ka nagkamali kahit lahat ginawa mo na para maging okay lang ang lahat. :)))))))))))))))))

IP Routing

The topic for today is about IP Routing. But first of all, I just want to share the agony I felt when I missed the quiz which I was prepared for. sayang! :(

Hehe, moving on. Today's topic is very interesting and I can say that I was able to understand it even though I failed to make the tutorial work at the first try. I was able to correct the configuration because of the illustration drawn on the board. The illustration shows the connection and addresses of routers and hosts that made me understand the topic. 

Figure 1: The illustration copied from the board showing connections and stating addresses

The pictures below show the step by step process of configuring the network consisting of two routers and two computers. (Tutorial)

Figure 2: Setting Up Router 1

Figure 3: Setting Up Router 2

After the routers were configured, the connections were tested through pinging addresses used in the configuration. If no packets were lost from the sent packets, it means that the configuration was correct.

Figure 4: Host 1 Pings The 3 Given Addresses

Figure 5: Host 2 Pings The 3 Given Addresses

The Exercise

The goal of the exercise is to make a network that consists of three hosts, three routers and a switch. The network should be configured such that all three computers can communicate with each other.

Figure 6: A screenshot of the Setup of the Network I configured

The pictures below show the step by step process of setting up router 1, router 2, and router 3.

Figure 7: Setting up Router 1

Figure 8: Setting Up Router 2

Figure 9: Setting Up Router 3

After the 3 routers were configured, the connections were tested through pinging. Each host pinged its respective co-hosts.

Figure 10: Host 1 Pinged Host 2 and Host 3

Figure 11: Host 2 Pinged Host 1 and Host 3

Figure 12: Host 3 Pinged Host 1 and Host 2

To wrap it all up, yesterday's lab class is fun yet disappointing when the blackout occurred. Understanding how connections between routers and hosts work is very interesting. Making this blog is harder than the exercise itself. All the cropping and layouting in photoshop is not hard but requires a lot of hard work. >:))

To my instructor, thank you for enlightening me about the topic through yesterday's class. More power! :)

Exercise 1: Introduction to Data Communications and Networking

Today, we discussed about Secure Shell (SSH). This is not the first time I encountered the term SSH. I once encountered it a couple of weeks ago when I uploaded a zip folder in a server and tutorials state that I need the support of ssh commands in order to unzip the folder in the server. But, it is always better to understand the basics than learning the more complicated topics because having a good foundation in everything that we learn is important.


The first item in the exercise is easy as eating a piece of cake. The picture below is a screenshot showing that a user was successfully added on my local computer. :)

The goal of the second item is to login to a remote computer (server) via SSH using a username-password combination. The username and password given to me was sgs and icsuser14 respectively. Exercise item number 2 is a little confusing and I was stuck because I didn't know the exact command to use since the instruction states that we need to see ssh manual to see how ssh is used given the IP address and a user account. Good thing my instructor said the command to use I was able to accomplish item number 2. The picture below shows that I connected successfully to the remote server via SSH.

Exercise item number 3 showed us to configure the local computer for a passwordless login. Picture below shows the randomart image for the generated public key.

I also learned that we can authorize keys so that we don't always have to enter our passwords when we need to access the server. The picture below shows that I hace logged in without having to type my password.

 Item number four in the exercise is the start of the fun part. We were able to broadcast messages. Picture below shows a message of mine broadcasted to the users connected to the remote computer.

And for the last item in the exercise, we need to exchange messages from a particular user. Picture below shows a conversation with user mcb.

For the last question:
If a different workstation is used to log in to the remote server, it will not be passwordless because the authorized key was saved on a local computer and it is not shared among other computers.


To wrap it all up, today's exercise was fun and it makes me think of ways on how to use public and private keys in protecting data being sent from one source to its destination. :)