A VPN tunnel: What is it, and how does it work?

What is a VPN tunnel?

A VPN tunnel is an encrypted connection between your device, like a computer, smartphone, or tablet, and the VPN server. It masks your IP address and encrypts your data that travels the internet, as well as the data you generate while surfing the web. Snoopers will not be able to gain access to your online data or track your activity because the connection is uncrackable without a cryptographic key.

VPN tunneling is a core function of all virtual private networks. VPN providers use different tunneling protocols, such as WireGuard or OpenVPN. These communication protocols allow data to move across the network.

How does VPN tunneling work?

VPN tunneling is the process of transmitting data from a device or network to another device or network and back without compromising data privacy. To enjoy the advantages of VPN tunneling, you must first start using VPN (a virtual private network) services. Once your device connects to a VPN, a safe tunnel is established even if you use public Wi-Fi.

What does a VPN tunnel do?

In the most basic terms, a VPN tunnel protects what you do online. It secures your connection and keeps your online activity hidden from anyone trying to monitor or interfere with your data. A VPN tunnel makes sure that:

• Your traffic is encrypted. Strong encryption protocols scramble your traffic, making it unreadable to hackers, ISPs, and other third parties. Even if someone manages to intercept it, they’ll see nothing but useless code.
• Your IP address is masked. As part of the VPN tunneling process, once your device establishes a secure connection with the VPN server, your internet traffic can be routed through that server. This process replaces your real IP address and virtual location with those assigned to the server. While the tunnel itself handles encryption and security, this rerouting makes it much harder for third parties to trace your activity back to you.
• Your connection is secured. You can use public Wi-Fi or another untrusted network without worrying about being tracked, monitored, or having your internet traffic intercepted.

When you connect to the internet without a VPN, a lot of your data packets can be exposed. Your ISP can view your activity, and websites can see your IP address and location. They can also throttle your bandwidth if you frequently download large files. Hackers have their own motives. They use malware, phishing, ransomware, DDoS attacks, and other techniques to intercept data and use it for their own gain.

With a VPN, your data packets go through an encrypted and secure tunnel, which protects your browsing activity, masks your IP address, and redirects your data to a VPN server. Neither ISPs nor hackers can identify you, snoop around your data, or track your location. The VPN tunnel is one of the most useful online security technologies available.

Good VPN services like NordVPN take it a step further. As one of the best VPN services, NordVPN combines fast and reliable VPN tunneling protocols with additional features like Threat Protection Pro™, which blocks malware, trackers, and malicious websites, creating an all-around cybersecurity solution to keep you safer online.

What is the process of VPN tunneling?

VPN tunneling doesn’t happen all at once. It’s a step-by-step process that kicks in the moment you hit "Connect" in a VPN app and ends when the session is terminated. Here’s how tunneling is accomplished in a VPN:

1. 1.Initiation of the VPN connection. This step starts when you launch your VPN app, choose a VPN server, and initiate a connection (click “Connect”). The app then begins to establish a connection with the VPN service, reaching out to the server and preparing to set up a secure link.
2. 2.Authentication and handshake. Your device and the VPN server perform mutual authentication. They verify each other’s identity using credentials or digital certificates. Then, something called a cryptographic handshake follows — the device and the VPN server agree on encryption parameters, exchange secure session keys, and sometimes confirm authentication details.
3. 3.Establishment of an encrypted tunnel. Once authenticated, your VPN creates a secure tunnel using protocols like WireGuard, OpenVPN, or IKEv2/IPSec. This tunnel creates a secure and encrypted pathway for your data to travel from your device to the VPN server, keeping outsiders from snooping on your internet traffic.
4. 4.Encryption of data and transmission. Your device encrypts every bit of data before sending it out. This step makes sure that no one else can read or use it, even if they manage to intercept it.
5. 5.Decryption at the VPN server. The VPN server receives the encrypted data, decrypts it using the agreed-upon keys, and sends it to its intended destination — the website you’re trying to visit. At this stage, it replaces your real IP address with its own, keeping your identity and location hidden.
6. 6.Return of data to the user's device. The website sends the data back to the server, which encrypts it again and sends it through the tunnel. Your device decrypts it, so the website loads normally on your end.
7. 7.Tunnel teardown. When you disconnect, the VPN shuts down the tunnel and wipes the session keys. That way, no trace of your encrypted session is left behind, and no one can reuse the same encryption keys in the future.

What are the types of VPN tunnelling protocols?

Many different VPN tunneling protocols exist, varying in speed, level of security, encryption processes, and other features. Let’s explore the most common types.

1. WireGuard

Security: Very high

Speed: Very high

The fastest protocol, and extremely useful when speed is your priority. It is also highly secure. WireGuard is extremely lightweight because it consists of just 4,000 lines of code, which leaves less room for vulnerabilities and flaws. It’s open source, which makes it transparent and easy to customize and debug.

WireGuard is still in the development stage and, unlike OpenVPN and IPSec, it requires its own infrastructure to function.

In 2019, NordVPN introduced NordLynx, a protocol that has inherited the speed of WireGuard and took it one step further by improving user privacy and the security that everyone strives for.

2. OpenVPN

Security: High

Speed: High

OpenVPN is an open-source protocol that works with all major operating systems. You can download the source code, review it, and modify it however you like. OpenVPN protocol can run over the TCP or UDP internet protocols. It is also considered one of the most secure VPN tunneling protocols and is quite fast.

As secure and fast as OpenVPN is, it proves to be quite complex to set up on your own.

3. IKEv2/IPsec

Security: High

Speed: High

The IKEv2/IPSec protocol offers the security benefits of IPSec (Internet Protocol Security) and has the speed of IKEv2 (Internet Key Exchange Version Two). When your VPN connection is interrupted or you’re switching between networks, the IKEv2/IPSec auto-connect feature restores everything back to normal.

As good a protocol as IKEv2/IPSec is, it is incompatible with some operating systems.

4. L2TP/IPsec

Security: Medium

Speed: Medium

L2TP (Layer 2 Tunneling Protocol)/IPSec accepts different encryption protocols, so you can easily customize it. It is also easy to set up with loads of documentation available.

L2TP/IPSec is not a very secure protocol because it is outdated, contains multiple vulnerabilities, and is potentially compromised by the NSA. It is a slow protocol because of the double encapsulation of data. Unlike SSTP, it is not good at bypassing firewalls.

5. SSTP

Security: High

Speed: Medium

SSTP is easy to set up and has accessible support. It’s a secure and relatively fast protocol that is good at bypassing firewalls.

Unfortunately, it only works on Windows. It was created by Microsoft, which is known to collaborate with the NSA.

6. PPTP

Security: Poor

Speed: High

PPTP is fast and convenient if you need a quick-use VPN. It is also highly compatible with every system and easy to set up and use.

It is an outdated protocol, which means it’s not secure and contains multiple exploits and vulnerabilities. The NSA is known to decrypt this protocol. Due to its primitive and outdated nature, it is easily blocked by firewalls.

What is VPN split tunneling?

A VPN tunnel encrypts all your traffic, but in some situations, you might not want it to. VPN split tunneling is a feature that lets you choose which parts of your internet traffic go through a secure VPN tunnel and which go through your regular internet connection. Instead of sending all your traffic through the VPN, you can route only selected apps or websites.

VPN split tunneling lets you protect sensitive activity, like online banking, while keeping other traffic, like streaming, outside the VPN for better speed.

Some VPN providers, like NordVPN, offer the split tunneling feature, while others only offer the standard VPN setup — full tunneling, which encrypts every byte of your internet traffic. You can find a detailed comparison of the two in our blog post on split tunnel vs. full tunnel VPN.

Does VPN split tunneling have any risks?

As handy a feature as VPN split tunneling is, it also means less protection for the traffic you leave out. The apps or websites you don’t route through the VPN connect to the internet directly, meaning they are outside of the encrypted VPN tunnel. Here are three main VPN split tunneling risks:

• Some of your traffic isn't protected. The traffic you route outside the VPN remains exposed. That traffic data outside the tunnel, like your IP address and activity, will still be visible to your ISP, third parties, or anyone monitoring the network.
• More ways for malware to sneak in. If you're using both secured and unsecured networks, attackers could use the unprotected side as a way into your device. If malware gets into your device through unsecured traffic, it could also eventually affect apps running through the VPN tunnel, especially if they share access to files or system resources.
• Higher risk on public Wi-Fi. If you're using split tunneling on public networks, excluded apps may transmit unencrypted data, leaving you vulnerable to eavesdropping, man-in-the-middle attacks, or data interception.

Used wisely, split tunneling is safe, but you need to consider when and how to enable it.

How does a VPN site-to-site tunnel differ from split tunneling?

Not all VPN tunnels work the same way — some secure entire networks, others just parts of your traffic. A site-to-site VPN creates a secure tunnel between two separate networks, like different branches in a company office, so they can securely share data between them. Split tunneling, however, lets you choose which internet traffic goes through the VPN tunnel and which doesn’t. To put it in simpler terms, one links entire networks, and the other manages traffic on a single device.

What are the advantages of a VPN tunnel?

A VPN tunnel provides strong privacy and security to your traffic, securing your connection from end to end. Here are the main VPN tunnel benefits:

• Stronger online security. A VPN tunnel encrypts your data, protecting it from hackers, trackers, and snoopers.

• Safer access to private networks. You can connect to your company’s internal systems or files more securely when working remotely.

• No activity-based bandwidth throttling. Some ISPs slow down your connection depending on what you’re doing online, like streaming or downloading large files. A VPN tunnel can help prevent it by making sure no one can trace your activity back to you.

• Less tracking and profiling. With your traffic hidden, third parties can’t easily collect data about you for ads or targeted content.

• Extra protection on public networks. On open networks like in airports or cafés, a VPN tunnel keeps your passwords, messages, and personal info safer.

Does a VPN tunnel have any disadvantages?

While the benefits are strong, you should also keep in mind a few downsides of VPN tunneling:

• Slight drop in connection speed. Encrypting your data and routing it through a VPN server can slow down your internet speed, especially with distant servers or heavy usage.

• Not all services work with VPNs. Some websites and streaming platforms may block VPN connections or limit access when they detect VPN usage.

Despite a few trade-offs, the security a VPN tunnel provides is definitely worth it.

What are the factors you should consider when choosing a VPN service?

When you’re choosing a VPN, you shouldn’t pick the first name you see online. A reliable VPN tunnel can protect your privacy, but only if the service behind it meets high standards. Do your research and look into these factors before committing to any provider:

• Supported VPN protocols. Look for services offering secure, modern protocols like WireGuard, OpenVPN, or IKEv2/IPSec. The protocols used for a VPN service determine how your data is encrypted and how well your VPN tunnel performs.
• Speed and performance. Encryption can slow your network speed down a bit. Make sure the provider has fast VPN servers and supports high-speed protocols so you’re not stuck with slow connections.
• Device and platform compatibility. Your VPN tunnel should work across all your devices, including your laptop, phone, tablet, and even your router, without the need for a complicated setup or technical know-how. Also, make sure the service lets you connect multiple devices at once under one account.
• Security features. A good service should offer strong data encryption, secure authentication, and features like a kill switch, DNS leak protection, or even split tunneling options. It’s even better if the VPN service provides additional security and cyber threat protection features.
• Server coverage. The more servers a VPN has in more locations, the more flexible and reliable your VPN connection will be.
• Reliable customer support. Problems happen. A trustworthy VPN service should offer responsive support and easy-to-use apps.

When weighing your options, remember — the difference between a free VPN and a paid VPN often shows in tunnel quality, speed, and security. Paid providers typically offer better protocol choices, more servers, and stronger encryption. For stable and secure VPN tunneling, a trusted paid provider is a better pick.

How to check if a VPN tunnel is established

When testing a VPN tunnel, you want to confirm that the VPN encrypts and routes your internet traffic securely through the tunnel, not just that you're connected to a VPN server. Here are three of the best ways to confirm that your VPN tunnel is active and working correctly:

1. 1.Check your IP address before and after connecting. Visit an IP-checking website before and after turning on your VPN. If your IP changes to one provided by the VPN server, it means your device is successfully connected to the server. However, this method only confirms the connection to the server, not that all your traffic is being encrypted through a secure VPN tunnel.
2. 2.Use network monitoring software. If you want to dig deeper into how your VPN tunnel is performing, network monitoring software is your best bet. These tools give you a detailed look at how your data is routed. They show whether your traffic is actually going through the encrypted tunnel or if it's leaking out unprotected.
3. 3.Run a DNS leak test. Although it’s not a direct tunnel testing method, a DNS leak test can help you spot potential issues. If the test shows that DNS requests are still routed through your ISP instead of the VPN’s DNS servers, it may mean parts of your traffic are not routed through the VPN tunnel.

Can a VPN tunnel be hacked?

A VPN tunnel can be hacked, but it’s rare, and usually only happens if the VPN uses weak encryption or outdated protocols. Hackers might exploit these gaps to intercept or decrypt your data. Also, if the VPN server itself is compromised or uses poor user authentication, it can open the door for attackers. A VPN server misconfiguration can also create vulnerabilities that attackers can target. However, breaking modern encryption itself is practically impossible.

With a trusted provider like NordVPN, you’re much safer. NordVPN offers modern VPN protocols like NordLynx, OpenVPN, and IKEv2/IPSec, backed by strong encryption and additional features like a kill switch and DNS leak protection. Plus, with the built-in Threat Protection Pro™ feature, you get an added layer of security against cyber threats.