Day 4: Working of a firewall

What comes to your mind when you see this?! Honestly me it's a "firewall" and am sure most of you thought so. 
When we come to the computing world, this is a metaphor for a firewall which is  a system designed to prevent unauthorized access to or from a private network. 
A firewall can be both a software and a hardware. Many people might be familiar of the software but hardware firewalls also exist! Many companies do have them in supply. 

These are examples of firewalls from the prominent network distributors l know. 
Firewalls can also be grouped in categories ie,

•  Packet-filtering firewalls;

   Used to control network access by monitoring outgoing and incoming packets and allowing them to pass or halt based on the source and destination Internet Protocol (IP) addresses, protocols and ports.

•  Stateful inspection firewalls (Dynamic packet filtering) 

Monitors the state of active connections and uses this information to determine which network packets to allow through the firewall.

•   Circuit-level gateways;

 These work at the session layer of the OSI model, or as a "shim-layer" between the application layer and the transport layer of the TCP/IP stack. They monitor TCP handshaking between packets to determine whether a requested session is legitimate.

•   Application-level gateways (a.k.a. proxy firewalls);

 Provides network security. It filters incoming node traffic to certain specifications which mean that only transmitted network application data is filtered.

•   Next-gen firewall;

 This is a deep-packet inspection firewall that moves beyond port/protocol inspection and blocking to add application-level inspection, intrusion prevention, and bringing intelligence from outside the firewall.

I hope that catches you up on firewalls.

What does a company systems administrator do?

Imagine you woke up and the news hit you that you're the new systems admin of a particular company!
I know right now what's running in your mind is programming and debugging, and yes, that's going to be on top of your worry list.
This is what you'll be tasked to do;

• Monitoring the system
•  Troubleshooting
• Installing software
• Performing backups
• Maintaining local documentation
• Adding and removing hardware
• Automating regular tasks

You sure won't escape the debugging part!

To succeed as a systems admin, you sure have to keep some of these practices in check,

• Be nice, it doesn't cost a penny.
• Always and always monitor your systems. The blame will 100% be on you if any system fails.
• Back up your files, don't wait to treat the patient rather than prevent the disease.
• Another good practice is to keep your users informed. Keep them updated on all the changes.
• And don't forget to implement robust security.

Okay, let's now do some networking. You'll need to know things like a hub, a switch, a router, a bridge, and these are all familiar terms l hope.

Briefly,

A hub is just a connection point for devices on a network.

Switch-connects computers on a network

Router- connects many networks

A hub is just a connection point for devices on a network.

A bridge- connects two sections of a network together.

How do you think the internet gets to your computer??

One may actually fail to break this down but try to decode this process

Router=>switch=>NIC=>device(pc)

NIC being a Network Interface Card that is found in a computer.

With this process model knowledge, please don't run to the router if your internet connection goes down, at least first deal with your NIC and upwards.

Day 2: How to use the GNU/Linux in programming

Just because l created this on the second day, l will still fill you in on the first day!
And this was all about getting to know each other and getting familiar with the course outline we are to cover during the internship period.
Oh, we are training from netLabsUG, located in Makerere. We are 18 interns from different learning institutes.
Cheers to day 2!!
So today we started programming in GNU/Linux. We basically did an introduction and installation of Linux on our machines, which was a success (well mine was successful).
I installed Ubuntu which is a distro of Debian and managed to write certain codes like mkdir- to create a new directory.