Troubleshooting VPN Connectivity: Dealing with IPv6 Issues on Linux

Are you experiencing difficulties connecting to a VPN due to IPv6-related complications? Fear not, you've come to the right place.

At times, when attempting to connect to a VPN through older firewalls or routes utilizing Point-to-Point or other tunnels, IPv4-based authentication may be in place. If your IP address is IPv6-based, it can pose a barrier to accessing the VPN or your data. However, there's a solution: suppressing IPv6 on your Linux machine.

Note: This guide focuses specifically on Linux systems. (For Windows check for the next set of blogs😘)

To suppress IPv6 and exclusively use IPv4 over IPv6, follow these simple steps:

→ Open terminal → Edit the "/etc/sysctl.conf" file as sudo using the gedit, nano, or vi editor. Example: I'm going to use nano

sudo nano /etc/systctl.conf

→ Now add the below lines at the end of the file.

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

Note: In case the above configuration lines are already present, just change the value from 0 to 1 . By default, most of the Linux machineIPv6 are disabled and might not have this above configuration

→ The above configuration disables IPv6 on all the interfaces. If you want to disable in particular interface, just add the below lines

net.ipv6.conf.<interface name>.disable_ipv6 = 1

Replace the string with the actual interface name in your system. Check interface details using ip a or ifconfig command.

→ Now, save the configuration. → Once you save the configuration. Give below command in terminal

sudo sysctl -p

→ Once it's successfully executed, in the terminal it shows the applied changes you have done in /etc/sysctl.conf

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🤩Stick with the old one(IPv4) when the new one(IPv6) gets tricky😵‍💫, Even in Networks😇

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