What is a virtual private dial-up network and how does it work?

What is a virtual private dial-up network?

A virtual private dial-up network (VPDN) is a secure, virtual version of old dial-up connections that allows employees to access their work network from anywhere, just like in the office.

VPDNs gave companies remote access without the headache of running large pools of modems or making traveling employees place long-distance calls to the office. A service provider managed the local dial-up infrastructure, while the company controlled user accounts, permissions, and access to internal resources.

​How does a virtual private dial-up network work?

A VPDN separates the physical dial-up connection from access to the organization’s private network. The service provider accepts the call and then forwards the session to the correct network:

1. 1.A remote user uses their computer to dial into their internet service provider (ISP) using a modem, just like old-school internet connections.
2. 2.Once connected to the ISP, the VPDN creates a secure tunnel over the internet to the company’s private network.
3. 3.The user logs in with a username and password to verify their identity.
4. 4.After logging in, the user can access the company’s private network, files, and applications as if they were in the office.

What are the main benefits of using a VPDN?

VPDNs made large-scale remote access more practical when dial-up was the main way to connect from outside an office. Their main benefits included:

• Wider remote access. A VPDN allowed employees to establish an encrypted connection to the company's private network  remotely.
• Lower infrastructure costs. Instead of requiring expensive dedicated physical lines, a VPDN utilized the public internet to create a private connection. Without the need for costly hardware for each remote user, enabling a remote workforce became inexpensive and easy to scale.
• Traffic protection. When paired with IPsec or another encryption protocol, a VPDN could protect traffic from interception and tampering as it traveled between the access provider and the company network.
• Centralized management. IT administrators could enforce security policies, authenticate users, monitor network activity, and grant or revoke access rights from one console.

VPDN vs. VPN

A VPDN is a legacy subset of VPN (virtual private network) technology that specifically uses dial-up, PPP, and L2TP to connect remote users to a private network. A VPN (virtual private network) is the modern, broad term for secure encrypted connections over any network. In short, VPDN is a specialized, older form of VPN, while VPN is the broad term for modern, secure network connections.

Here are a few main differences between them:

• Connection method. VPDNs rely on dial-up modem pools and the PSTN (Public Switched Telephone Network), while VPNs use high-speed broadband or mobile internet.
• Protocols. A VPDN can use PPTP, L2F, and L2TP protocols. VPNs use WireGuard or proprietary protocols, such as NordLynx.
• Status. Rarely used today, a VPDN is considered a legacy technology. VPN is the modern, industry-standard replacement for remote access and site-to-site connectivity.