What is HTTP

What port does it use?

HyperText Transfer Protocol

  Enables users to retrieve web pages from a server and interact with the pages using their web browsers.

Uses port 80

What is HTTPS?

What port does it use?

Secure HTTPS 

Designed to be secure and uses SSL certificates to be able to verify that you are connected to is the server you asked for.

Uses port 443

What is FTP 

What port does it use?

File Transfer Protocol

 Makes it possible to transfer files between a local and a remote host or to create and alter directories on a remote system. 

uses ports 20 and 21

What is SSH 

What port does it use?

Secure Shell 

it is used to create a secure tunnel between devices/ 

Enables you to log on to a remote computer or network device using a secure, encrypted connection.

Dynamic Host Configuration Protocol

There is a server that leases IP addresses from a pool of IPs that it sends to host machines.

When a host is connected to a network it will request a DHCP IP address from the DHCP server.

Transmission Control Protocol

Must establish a connection on both ends before data can be sent.

Syncs up data in the correct order if the sending machine sends data pacakets out of order.

Internet Control Message Protocol

is an error-reporting protocol network devices like routers use to generate error messages to the source IP address when network problems prevent delivery of IP packets. ICMP creates and sends messages to the source IP address indicating that a gateway to the Internet that a router, service or host cannot be reached for packet delivery.

What are IP Classes?

For the IP address that most people are familiar with (IPv4), there are 4 sets (octets) of numbers, each with values of up to 255. You likely have run into this when troubleshooting a router or a DHCP server, when they are giving out addresses in a particular range- usually 192.x or 10.x in the case of a home or commercial network. IP classes are primarily differentiated by the number of potential hosts they can support on a single network. The more networks supported on a given IP class, the fewer addresses are available for each network. Class A networks run up to 127.x.x.x (with the exception of 127.0.0.1, which is reserved for loopback or localhost connections). These networks are usually reserved for the very largest of customers, or some of the original members of the Internet and xkcd has an excellent map (albeit a bit dated) located here showing who officially owns what. Class B (128.x to 191.x) and Class C (192.x to 223.x) networks are much more fuzzy at the top level about who officially owns them. Class C addresses are primarily reserved for in-house networks which is as we mentioned above why so many different manufacturers use 192.x as their default setting. Class D and E are reserved for special uses and normally are not required knowledge.

Domain Name Server

DNS is the Internet’s phone book. The Domain Name System is what makes it possible to only have to remember something like “cnn.com” instead of (at this particular moment) “157.166.226.26”. IP address change all the time however, although less so for mega-level servers. Human friendly names allow users to remember a something much easier and less likely to change frequently, and DNS makes it possible to map to those new addresses under the hood. If you were to look in a standard phone book and you know the name of the person or business you’re looking for, it will then show you the number for that person. DNS servers do exactly the same thing but with updates on a daily or hourly basis. The tiered nature of DNS also makes it possible to have repeat queries responded to very quickly, although it may take a few moments to discover where a brand new address is that you haven’t been to before

What is a Firewall?

acts as a barrier between a trusted system or network and outside connections, such as the Internet. However, a computer firewall is more of a filter than a wall, allowing trusted data to flow through it.

A firewall can be created using either hardware or software. Many businesses and organizations protect their internal networks using hardware firewalls. A single or double firewall may be used to create a demilitarized zone (DMZ), which prevents untrusted data from ever reaching the LAN. 

Services are programs that run in the background based on a particular system status such as startup. Services exist across nearly all modern operating systems, Services also have the ability to set up actions to be done if the program stops or is closed down. In this way, they can be configured to remain running at all times.

A subnet mask tells the network how big it is. When an address is inside the mask, it will be handled internally as a part of the local network. When it is outside, it will be handled differently as it is not part of the local network. Used to devide the host from the network.

127.0.0.1 is the loopback connection on your network interface card (NIC)- pinging this address will see if it is responding. If the ping is successful, then the hardware is good. If it isn’t, then you might have some maintenance in your future. 127.0.0.1 and localhost mean the same thing as far as most functions are concerned

A workgroup is a collection of systems each with their own rules and local user logins tied to that particular system. A Domain is a collection of systems with a centralized authentication server that tells them what the rules are. While workgroups work effectively in small numbers, once you pass a relatively low threshold (usually anything more than say 5 systems), it becomes increasingly difficult to manage permissions and sharing effectively. To put this another way, a workgroup is very similar to a P2P network- each member is its own island and chooses what it decides to share with the rest of the network. Domains on the other hand are much more like a standard client/server relationship- the individual members of the domain connect to a central server which handles the heavy lifting and standardization of sharing and access permissions.

The three basic ways to authenticate someone are: something they know (password), something they have (token), and something they are (biometrics). Two-factor authentication is a combination of two of these methods, oftentimes using a password and token setup, although in some cases this can be a PIN and thumbprint.

Address Resolution Protocol

ARP allows for the mapping of IP addresses to MAC addresses. In this way it lets systems go from a regular domain name down to the actual piece of hardware it resides upon.

Encrypted File System

The Encrypted File System, Microsoft’s built-in file encryption utility has been around for quite some time. Files that have been encrypted in such a way can appear in Windows Explorer with a green tint as opposed to the black of normal files or blue for NTFS compressed files. Files that have been encrypted are tied to the specific user, and it can be difficult to decrypt the file without the user’s assistance.