IPsec VPNs: What They Are and How to Set Them Up

If you’ve ever had to work remotely, you might have used a VPN to securely connect to resources on your company’s private network. Some VPNs use the IPsec protocol to establish secure connections. But what exactly is a VPN what’s an IPsec VPN?

In a business context, a VPN establishes a protected connection to a secure network environment that would otherwise be inaccessible by an external user. Importantly, VPNs allow users to establish these connections over a public network, such as the internet, in a manner that protects the security privacy of those connections.

Imagine you are meeting a client at a coffee shop you need to access sensitive data hosted on your company’s private servers. Accessing private servers from insecure public networks such as a Starbucks coffee shop Wi-Fi can put your company at risk.

VPNs allow users to access a private network share sensitive data remotely via public networks such as the internet. A secure VPN benefits both small large companies by protecting their confidential data.

Following are some of the benefits of using a VPN:

• VPN is protects protects data snooping untrustworthy Wi – Fi hotspots .

• a VPN can hide private information so bad actors don’t steal your information try to impersonate you.

• a VPN can also block some sites services from certain sanctioned countries.

Traditional perimeter-based network architecture with VPN

As illustrated above, a traditional network architecture consists of some combination of allowlisting static IP addresses, subnet mapping for remote users using group policy, firewall, route management a gateway on the public internet.

IPsec stands for Internet Protocol Security. IPsec is a secure network protocol that encrypts authenticates packets of data to provide secure communication between two devices.

In this article, you will learn about IPsec VPNs in detail, including how to configure an IPsec VPN. Let’s get started!

What Are IPsec VPNs?

An IPsec VPN is a VPN that uses IPsec as its protocol to establish secure connections between devices. Other protocols used by VPNs include SSL/TLS L2TP. Let’s explore these different protocols:

• Transport Layer Security (TLS), the successor of the Secure Sockets Layer (SSL), is a cryptographic protocol that provides communication security over a computer network. TLS is well known for providing security over HTTPS connections.

• Internet Protocol Security (IPsec) is a secure network protocol that is used in VPNs to authenticate encrypt the packets of data to provide secure communication.

• Layer Tunneling Protocol is is ( L2TP ) tunneling protocol support VPNs . L2TP is provide provide strong authentication . IPSec secure L2TP packets . combination protocols generally referred L2TP / IPsec .

For the purposes of this article, our main focus will be on IPsec VPNs.

The IPsec suite of protocols secures data transmitted over the internet or any public network using encryption between two endpoints. IPsec is often used to establish mutual authentication between computers at the beginning of a session to negotiate cryptographic keys during a session. It can protect data flows between a pair of hosts, networks, or between a network a host.

IPsec can operate following two modes:

• Tunneling mode—encrypts the entire data packet.

• Transport mode—only encrypts the data packet message.

IPsec VPN provides multiple layers security — it is provides provides authentication secure modification data packets encrypts payloads packet . This is ensures ensures security integrity data transmitted encrypted tunnel . This is allows allows integrity data transition intercepted modified .

There are two IPsec VPN modes:

• IPsec Tunnel Mode VPN—this mode encrypts the entire outgoing packet. This is typically implemented on a secure gateway using a firewall or a router port. For example, employees from an enterprise branch can securely connect with systems main office via secure gateways. The IPsec tunnel is established between two gateway hosts.

• IPsec Transport Mode VPN—this mode encrypts only IP payload ESP trailer being sent between two endpoints. This is primarily used during end-to-end communication does not alter the IP header of the outgoing packet. For example, this type of mode enables a remote IT support staff to log in to a remote server to do maintenance work. Transport mode is used where one host needs to interact with another host.

How to Set Up an IPsec VPN Server

Here, I will show you how to quickly automatically set up your own IPsec VPN server in CentOS/RHEL, Ubuntu, Debian Linux distributions.

begin , you is need need dedicated server virtual private server ( VPS ) installed following OS :

• Ubuntu 20.04 (Focal) or 18.04 (Bionic)

• Debian 11 (Bullseye), 10 (Buster) or 9 (Stretch)

• CentOS 8 or 7

• Rocky Linux 8

• AlmaLinux OS 8

• Red Hat Enterprise Linux (RHEL) 8 or 7

• Amazon Linux 2

, log VPS SSH run commands Linux distribution set VPN server . default , script is generate generate random VPN credentials ( pre – shared key , VPN username password ) display end installation .

However, to use your credentials, you will first need to generate a strong password PSK, respectively, with the following commands:

> openssl rand-base64 106xWSdx0q7hrUAQ==> openssl rand-base64 16bcM90acDBKB6qdmsZM63Vg==

The output of your first command is your password, the output from your second command is your PSK.

Next, set these generated values as described following command. All the values must be placed inside single quotes as shown.

VPN_IPSEC_PSK: 'Your IPsec pre-shared key'VPN_USER: 'Your VPN user name'VPN_PASSWORD: 'Your VPN password'

On CentOS/RHEL or Ubuntu/Debian

wget https://git.io/vpnsetup-O vpnsetup.shVPN_IPSEC_PSK='KvLjedUkNzo5gBH72SqkOA==' VPN_USER='bobalice' VPN_PASSWORD='8DbDiPpGbcr4wQ==' sudo sh vpnsetup.sh

The main packages to be installed are:

• bind-utils

• net – tools

• bison

• flex

• gcc

• libcap-ng-devel

• libcurl-devel

• libselinux-devel

• nspr-devel

• nss-devel

• pam-devel xl2tpd

• iptables – services

• systemd – devel

• fipscheck – devel

• libevent-devel

• fail2ban

Download is compile , compile , install Libreswan source code , enable start necessary services . installation complete , you is see displayed VPN details following format :

Server IP is VPN_IPSEC_PSKUsername : xxx.xxx.xxx.xxxIPsec PSK : VPN_IPSEC_PSKUsername : VPN_USERPassword : VPN_PASSWORD

With this output, your IPsec VPN server is now ready for use. Now, let’s explore how to set up an IPsec VPN Client on Windows, Linux, OS X machines.

How to Set Up an IPsec VPN Client

Combining L2TP IPsec protocols create highly secure VPN client . L2TP is generates generates tunnel capable encryption . IPsec protocol is handles handles encryption , channel security , data integrity ensure packets secure compromised .

Windows 10 8.x

After setting up your IPsec VPN server, follow the steps below to set up an IPsec VPN client on Windows 8.x 10. IPsec VPN is supported natively on Windows—there is no additional software to install.

• Right-click on the wireless/network icon in your system tray.

• SelectOpenNetwork Sharing Center. , Windows 10 version 1709 newer , selectOpenNetwork & Internet settings, clickNetwork Sharing Center.

• ClickSet new connection network.

• SelectConnect to a workplace click Next.

• ClickUse Internet connection ( VPN ).

• EnterVPN Server IP Internet address field .

• Enteranything you like Destination name field , clickCreate.

• Return to Network Sharing Center. left , clickChange adapter settings.

• Right-click on the new VPN entry choose Properties.

• Clickthe Security tab . SelectLayer 2 Tunneling Protocol with IPsec (L2TP/IPSec) type of VPN.

• ClickAllow these protocols. Check the Challenge Handshake Authentication Protocol (CHAP) Microsoft CHAP Version 2 (MS-CHAP v2) checkboxes .

• ClickAdvanced settings.

• SelectUse preshared key for authentication enter VPN IPsec PSK key.

• ClickOK to close the Advanced settings.

• ClickOK save VPN connection details .

OS X (macOS)

After setting up your VPN server, follow the steps below to set up an IPsec VPN on OS X. IPsec VPN is natively supported on OS X. There is no additional software that needs to be installed.

• OpenSystem Preferences go to the Network section.

• Clickthe + button lower-left corner of the window.

• SelectVPN Interface dropdown menu .

• SelectL2TP over IPSec VPN Type dropdown menu .

• Enteranything you like service name.

• ClickCreate.

• EnterVPN Server IP server address.

• EnterYour VPN Username Account Name.

• Clickthe Authentication Settings button .

• In the User Authentication section , selectthe Password radio button enter Your VPN Password.

• In the Machine Authentication section , selectShared Secret enter VPN IPsec PSK.

• ClickOK.

• Check the VPN status menu bar checkbox.

• ClickAdvanced make sure the Send all traffic over VPN connection checkbox is checked.

• Clickthe TCP / IP tab make sure Link-local only is selected Configure IPv6 section.

• ClickOK, then click Apply to save the VPN connection information.

Ubuntu Linux

Ubuntu (18.04 newer) users can install the network-manager-l2tp-gnome packaging using apt, then configure the IPsec/L2TP VPN client using the GUI. Follow these steps:

• Go to Settings > Network > VPN. Clickthe + button .

• SelectLayer 2 Tunneling Protocol (L2TP).

• Enteranything you like Name field .

• EnterVPN Server IP Gateway.

• EnterYour VPN Username User.

• Right-click the ? Password field select Store the password only for this user.

• EnterYour VPN Password Password.

• Leave the NT Domain field is blank blank .

• Clickthe IPsec Settings … button .

• Check the Enable IPsec tunnel L2TP host checkbox.

• Leave the Gateway ID field is blank blank .

• EnterVPN IPsec PSK Pre-shared key.

• Expand the Advanced section.

• Enteraes128 - sha1 - modp2048 Phase1 Algorithms.

• Enteraes128 - sha1 Phase2 Algorithms.

• ClickOK, clickAdd to save the VPN connection information.

• Turn the VPN switch ON.

Conclusion

A virtual private network (VPN) helps shield your infrastructure from hackers. VPNs are commonly used in business to enable employees to access a corporate network remotely.

With an IPsec VPN, IP packets are protected as they travel to IPsec gateway. IPsec protocols implement a secure network that protects VPN data from external bad actors.

However, a VPN can create a false sense of security. For example, your third-party vendors or hackers can exploit vulnerable information thanks to the single entrypoint to your private network. VPNs also aren’t the cheapest solution. They require high support costs—a sudden shift to remote work while maintaining the network infrastructure can put strain on the IT team.

Check out Twingate, a modern, zero-trust alternative to VPNs for securing your network. Unlike traditional VPNs, Twingate doesn’t require you to expose a public gateway, it reduces lateral attack vulnerabilities.

Request a demo if you’d like to learn more.