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What Is an Intranet? Difference from Internet and Extranet, How to Build One

An intranet is the internal network and portal only employees can reach. How it differs from the internet and an extranet, how to build it, and remote access.

Oğuzhan Gerçek··6 min read
What Is an Intranet? Difference from Internet and Extranet, How to Build One

Short answer: An intranet is an organization's private network, open only to its own employees, and the internal portal served on it: announcements, documents, HR transactions, the directory and workflows live there. It uses the same technology as the internet (TCP/IP, web browsers, DNS) but is not open to the public; the version opened to partners or customers as well is called an extranet. Today an intranet usually runs as a cloud service and means "internal applications you sign in to" more than "the internal network", which is why its security starts with identity rather than the network perimeter.

What is an intranet?

By Wikipedia's definition, an intranet is a computer network set up within an organization for sharing information, communication, collaboration tools and operational systems; it is generally restricted to the organization's employees. In practice it has two layers. The first is the network itself: the office LAN, the links connecting branches, the servers and their addressing scheme. The second is what the employee sees: the company portal opened in a browser. A portal typically holds:

  • Announcements, news and management messages
  • A document and procedure library (quality documents, policies, forms)
  • HR self-service: leave, payroll, expenses, training
  • The employee directory and the organization chart
  • Help desk and request forms (IT, facilities)
  • Team spaces, a wiki and project pages

The portal can run on an on-premises server or on a cloud service such as SharePoint, Confluence or Google Sites. The technology is the same; the difference is who can get in.

Intranet, internet and extranet

  • Internet: The public global network. The company website lives here; no sign-in required.
  • Intranet: Open only to the organization's employees. Content is invisible outside the organization, and access is limited by authentication.
  • Extranet: Selected parts of the intranet opened to outside parties such as suppliers, dealers or customers: an order portal, a dealer panel, a project room. Wikipedia draws the same line: while an intranet is restricted to employees, an extranet may also be accessed by customers, suppliers and partners.

All three run on the same protocols; what draws the boundary is network topology and identity policy.

How does an intranet work?

It is made of four parts:

  • Network: The office LAN, the links between branches and the segmentation of the network with VLANs; the DNS that resolves internal names.
  • Identity: The directory that holds employee accounts (Active Directory or a cloud directory), single sign-on (SSO) and multi-factor authentication. The question of who may access what is answered here; details are in the IAM article.
  • Applications: The portal, document management, business email and messaging; each is tied to the directory, so a new employee enters everything with one account and a leaver is switched off in one place.
  • Access: Direct in the office; from outside through VPN or ZTNA.

How to build an intranet

  1. Needs list: A portal, document management or HR self-service; first, where the answers to the five most asked questions will live.
  2. Platform decision: On-premises server or cloud service. A cloud service reduces the operational load; where the data resides is decided separately under KVKK, because employee data sits on the intranet.
  3. Identity integration: The directory and SSO are connected from day one; an intranet that asks for a separate password goes unused.
  4. Content ownership: Every section has a written owner and update frequency; an ownerless intranet goes stale within six months.
  5. Access and security: Role-based permissions, MFA, network segmentation, access logs.
  6. Measurement: Who searches for what and which page cannot be found; the search logs are the portal's roadmap.

Is an intranet secure?

The most common misconception is the assumption that "it is secure because it is on the internal network". NIST's Zero Trust Architecture (SP 800-207), published in August 2020, rejects that assumption outright: no implicit trust is granted to assets or user accounts based solely on their physical or network location, and protection is applied to resources (applications, data, services), not to network segments. In practice that means four rules:

  • Identity is verified on every access; coming from the office network grants no permission.
  • Permissions are granted by role and with least privilege; not everyone sees HR documents.
  • The network is segmented; intranet servers, user devices and the guest network do not sit in the same segment. The method is in the network security article.
  • Access is logged and retained; the question of who opened which document and when must be answerable.

Then there is the data side: employees' personal data (identity, payroll, medical reports) sits on the intranet; limiting access and setting retention periods is a KVKK matter.

Remote access to the intranet: VPN or ZTNA?

The classic route is VPN: the employee joins the corporate network through an encrypted tunnel and reaches the intranet as if in the office. Its problem is that the device entering the tunnel sees the whole network. ZTNA instead connects the user to individual applications rather than to the network; identity, device state and permissions are checked on every request. The difference between the two, and which fits which situation, is in the VPN article. Cloud-based intranets have a third route: the portal is reachable from the internet anyway, and the boundary is drawn by identity and MFA, not by the network.

The operations side

The invisible side of an intranet is the operation of the directory, email and collaboration platforms: the user lifecycle, mail flow security, permission changes. We describe that layer in our collaboration and messaging platforms service, the identity side in identity management, and network segmentation and zero-trust architecture on the network security page.

Frequently asked questions

What does intranet mean? An internal network: a private network built on internet technology, open only to the organization's employees, and the internal portal on it.

What is the difference between an intranet and the internet? The internet is the public global network; an intranet is built with the same technology but open only inside the organization. The company website lives on the internet, the employee portal on the intranet.

What is an extranet? Selected parts of the intranet opened, with authentication, to outside parties such as suppliers, dealers or customers; an order portal and a dealer panel are typical examples.

Which software is used for an intranet? On-premises portal software or cloud services such as SharePoint, Confluence or Google Sites. What decides the choice is less the software than identity integration, data location and content ownership.

How do you connect to the intranet from home? By joining the corporate network with a VPN, or by connecting directly to the application with ZTNA; on cloud-based portals, from the browser with identity and MFA.

Are an intranet and a VPN the same thing? No. The intranet is the network and the applications being accessed; a VPN is one of the ways of connecting to that network securely from outside.

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