OpenVPN Not Working with UDP NAT Gateway on OpenWrt
In this article, we will discuss the issue of OpenVPN not working with UDP NAT gateway on OpenWrt. We will cover the key concepts, provide detailed context on the topic, and offer solutions to this problem.
Introduction
OpenVPN is an open-source virtual private network (VPN) software that allows users to create secure and encrypted connections between computers. OpenWrt is an open-source firmware for routers that provides advanced features and customization options. NAT (Network Address Translation) is a method of remapping one IP address space into another by modifying network address information in the IP header of packets while they are in transit.
The Problem
The user is running OpenVPN on OpenWrt and has added a rule to forward TCP/UDP port number 1194 to the VPN server NAT. However, everything works with TCP, but UDP does not seem to be working.
Solution
The solution to this problem is to ensure that the UDP port forwarding rule is correctly configured. By default, OpenWrt uses iptables as its firewall, and the following command can be used to add a UDP port forwarding rule:
iptables -t nat -A prerouting_rule -i -p udp --dport 1194 -j DNAT --to
Where
Checking the Configuration
To check if the UDP port forwarding rule is correctly configured, the following command can be used:
iptables -t nat -L prerouting_rule -n -v
This command will list all the rules in the prerouting chain, and the user can check if the UDP port forwarding rule is present. If the rule is not present, then the user needs to add the rule again.
In this article, we have discussed the issue of OpenVPN not working with UDP NAT gateway on OpenWrt. We have covered the key concepts, provided detailed context on the topic, and offered solutions to this problem. By following the steps outlined in this article, users should be able to resolve the issue and get OpenVPN working with UDP NAT gateway on OpenWrt.
References
- OpenVPN: https://openvpn.net/
- OpenWrt: https://openwrt.org/
- NAT: https://en.wikipedia.org/wiki/Network_address_translation
- iptables: https://linux.die.net/man/8/iptables