Problems with routing in Softether VPN

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kaweewattt
Posts: 4
Joined: Wed Dec 27, 2023 6:18 pm

Problems with routing in Softether VPN

Post by kaweewattt »

Cannot set IPv4 route when using Softether VPN.

I am trying to set route for specific IP range through VPN.
But when connection is made it ends up putting 0.0.0.0/1 through VPN.

No problem when using SSTP, only for Softether VPN.

My setting

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Route after connection was made

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kaweewattt
Posts: 4
Joined: Wed Dec 27, 2023 6:18 pm

Re: Problems with routing in Softether VPN

Post by kaweewattt »

Look like bugs when using DHCP



Route after set fixed IP address... still incorrect

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Route after set fixed IP and fixed gateway ... correct

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admin
Site Admin
Posts: 673
Joined: Fri Feb 15, 2019 4:04 pm
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Re: Problems with routing in Softether VPN

Post by admin »

Hello,

this is not a bug but is expected behavior.
DHCP client sets default gateway when receiving DHCP_OP_ROUTER (0x03) option
The DHCP client is only used if a static address is not set.
However the VPN log shows what happens
kaweewattt
Posts: 4
Joined: Wed Dec 27, 2023 6:18 pm

Re: Problems with routing in Softether VPN

Post by kaweewattt »

That is not supposed to happened when "redirect gateway" is unchecked.

If that is supposed to happen.... how can I redirect just a specific target IP range through VPN (in my case 192.168.99.0/24) but not the public IP (such as google.com)?

When I am using SSTP that is not a problem with the same VPN server and the same route setting.
kaweewattt
Posts: 4
Joined: Wed Dec 27, 2023 6:18 pm

Re: Problems with routing in Softether VPN

Post by kaweewattt »

My route with same setting but in SSTP protocol
which is totally different compared to Softether protocol

I can route specific IP range through VPN while accessing web/internet content bypassing VPN.

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admin
Site Admin
Posts: 673
Joined: Fri Feb 15, 2019 4:04 pm
Contact:

Re: Problems with routing in Softether VPN

Post by admin »

The "Redirect gateway" options is used to force the client to redirect all packets regardless of the server configuration.

This happens because they are two different protocols.
The SSTP protocol is configured through the PPP protocol, while the SoftEther protocol is configured with the DHCP protocol.
The SoftEther server Virtual HUB most likely has Secure NAT enabled. If so you can edit the Secure NAT configuration and remove the Default Gateway Address. In this way the DHCP client will no longer receive the DHCP_OP_ROUTER option and so not set the default routes
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