L2TP/IPsec from IPv6 clients

[dongjuanyong]

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Prerequisites

• [ Y ] Can you reproduce?
• [ Y ] Are you running the latest version of SoftEtherVPN?

SoftEther version: 5.01.9670
Component: Server
Operating system: Linux(OpenWrt)
Architecture: X86_64

Processor: Intel(R) Pentium(R) CPU N3710

Description

Sorry for my English. I compiled SoftEther VPN server 5.01.9670 from OpenWrt packages feed and installed it on my router. It runs OK, but when I tried to connect to my router through L2TP/IPsec from my office (I used IPv6 to connect), it failed to connect. I used to have a stable version of v4.29-9680-rtm before. With the same configuration (I tried exactly the same vpn_server.config file, and also from a fresh reconfiguration), L2TP/IPsec from IPv6 clients worked without any flaws. What I found was that "netstat -lnp" showed the 5.01.9670 versions listened to udp port 1701, 4500 and 500, but only IPv4 of them. The v4.29-9680-rtm listened to further more, including udp :::1701, :::4500 and :::500, raw protocol 50 and 52 for both IPv4 and IPv6. I think that may be the problem.

Expected behavior:
The server listens to udp 1701, 4500, 500 and raw protocol 50, 52 for both IPv4 and IPv6. Thus we can make L2TP/IPsec connections from IPv6 clients.

Actual behavior:
I can't connect L2TP/IPsec VPN from IPv6 clients.

Steps to reproduce

1. Install 5.01.9670 version of server and run. Try to connect L2TP/IPsec VPN from IPv6 clients and use "netstat -lnp" to find out what ports is it listening to.
2. Install v4.29-9680-rtm version of server and run. Try to connect L2TP/IPsec VPN from IPv6 clients and use "netstat -lnp" to find out what ports is it listening to.

[chipitsine]

nice report, btw

[chipitsine]

@Andy2244 , can you have a look, please ?

[Andy2244]

mhh if your openwrt version was compiled with ipv6 (default) support, than ipv6 "should" work.
I personally only use the softether protocol via ipv4, so have not personally tested the other permutations, so i rely on user feedback for those.

@chipitsine Is there a specific build option for ipv6, i should check, be aware of or maybe a daemon start option?