ITS:Terminology and explanation. - ConnorEast/Tech-Journal GitHub Wiki

Ports:

Ports are software-based virtual points that allows for network connection transfers. Each port is assigned to a specific service/Proccess. Ports increase network connection more efficient as it cuts down on overlapping requests.

Port 25 ---> SMTP ---> Used for Email.
Port 465 ---> SMPTS ---> SSL encrypted SMTP.
Port 587 ---> MSA ---> Same as 465 but helps stop outgoing spam when port 25 is blocked.

Port 110 ---> POP3 ---> Allows individuals to connect to a mail server.
Port 995 ---> POP3S ---> POP3 but with added ssl encryption.

Port 143 ---> IMAP ---> Used to access email messages from a mail server.
Port 993 ---> IMAPS ---> SSL encrypted version of port 143.

Port 80 ---> HTTP ---> used for websites and the world wide web (insecure).
Port 443 ---> HTTPS ---> used for websites and the world wide web (Secure).

Port 119 ---> NNTP ---> used to transport UseNet news articles.
Port 563 ---> NNTPS ---> Same as 119 but, with SSL encryption.

Port 20:21 ---> FTP ---> Transfers content between client and server.
Port 23 ---> Telnet ---> Used to remotely access a terminal emulation
Port 22 ---> SSH/SCP/SFTP ---> Used for Secure Shell Tunneling Protocol.

Port 53 ---> DNS ---> Matches IP address to domain names, enabling users to not have to memorize IP addresses.
Port 123 ---> NTP ---> Allows clock computers to sync with each other. Necessary for encryption.
Port 179 ---> BGP ---> used for establishing data transfer routes. Broadcasts IP address control.
Port 500 ---> ISAKMP ---> used for creating secure IPsec (VPN) connections.

OSI Model:

The OSI model is a conceptual model which enables diverse communication systems to communicate using standard protocols. It consists of seven abstracted layers.

  • Layer 1: Physical Layer ---> Transmits raw bit stream over physical medium; ---> Cables, Switches, Binary.
  • Layer 2: Data-link layer ---> Defines data format on network; ---> Facilitates data transfer between devices on the same network
  • Layer 3: Network layer ---> Facilitates transfers between two different networks; ---> Protocols: ICMP/IGMP/IPsec
  • Layer 4: Transport layer ---> Transmits data using TCP, UDP, etc; ---> Responsible for flow Control
  • Layer 5: Session layer ---> Controls ports and sessions in order to maintain connections ---> this sector ensures communication between devices concludes before the session closes.
  • Layer 6: Presentation layer ---> Ensures data formatting in usable when data encryption occurs ---> Used for encryption, translation, and compression of data
  • Layer 7: Application layer ---> Human-Computer Interactions, where applications gain access to network services. ---> Protocols: HTTP/SMTP

vCenter;

vCenter is a virtualization server installed directly onto a server. It acts as a central administration point for ESXi hosts and their virtual machines. a vCenter server consists of the following: vSphere Clients [ESXi host servers], vCenter Server database [Centralized Database for VCenter Server], vCenter Single Sign on [Only allows one authentification measure for AD/LDAP], and managed hosts [ESXI hosts and VM's].
Major Ports: 80(http), 443(https), 902(allows for Vcenter, VSphere Connectivity).

vSphere;

vSphere is a virtual server environment created by vCenter for each ESXI host. Think of it as a portal into the system. This hosts the majority of virtual machines I work on.

DNS ---> Domain Name Server;

The DNS takes the URL that is typed into a URL. and then it goes through the query line first contacting the root nameserver who contact the Top-Level Domain, Then the DNS server. The DNS server returns the translation of the name into an active IP address. This allows for individuals to look up specific URLs without having to have people memorize ip addresses.
Major Ports: 53 (DNS);

ADDS ---> Active Directory Domain Services;

An Active Directory Server essentially allows for the configuration of object variables that affects how a server works. For instance, once a windows device is set up to automatically join a domain it creates a computer object. This is a direct tie to the hardware so any changes added to the AD will effect the software on the secondary computer. Some other objects contain users, computers,

DHCP ---> Dynamic Host Configuration Protocol;

DHCP is used for the allocation of IPs to client devices based on specific criterion of what is available. The information between the two are transferred using a protocol known as DORA. DORA is explained below. A DHCP server can be created using either a Linux server or a windows active-directory server. The main information that is being allocated consists of the IP Address, Subnet Mask, Default-Gateway, and the DNS-Server.

DORA --> DHCPDiscover, DHCPOffer, DHCPRequest, DHCPPack;

Dynamic Host configuration uses protocol Dora which runs on UDP ports 68 (Client) and 67 (Server). DHCPDiscover is where the client (68) messages the server (67) to ask what available IP addresses there are. The server (67) sends a message back known as DHCPOffer which states what IPs are available. The Client (68) Then sends a DHCPRequest asking for a specific IP address from the list in the offer. The Server(67) then sends a DHCPPack, also known as an acknowledgement back to the client(68) and it leases the IP.