SoftEther VPN User Forum

Posted: **Sat May 25, 2024 12:31 am**

I have a VPN with softether running and I don't understand why I see a virtual machine on my network with random macs that always start with DA-xx-xx-xx-xx.

Let me explain. My softether configuration does not have its own DHCP but uses the dhcp of the main network. The thing is that as network equipment with ip I always have 2 when there is no one connected to the VPN, and if I connect with my mobile to the VPN the IP number 3 appears.

The problem is that those 1 fixed ips are always there but not with the same MAC, there are 1 of them that have fixed MAC but the other does not. The MAC changes every time I turn the VPN off and on (offline to online) but it always gives me a MAC starting with DA-xxxx.

Can I make that ip and that mac not exist, can I always set the same mac so that it doesn't change by itself?

I put a photo to see if it is better understood. With the VPN turned off, none of the 2 ips are visible (and macs).

When I turn on the VPN, the 2 ips (and macs) appear.

I see that one is controlled from softether and it always gives me the same MAC.

But I don't understand what is the other IP, which has random MACs. Although those random MACs always start with DA-xx-xx.... How can I leave this mac fixed so that it is not random?

Posted: **Sat May 25, 2024 1:07 am**

Sure...

Added the new function to reserve and each Virtual MAC address and IP address for each user of L2TP/IPsec, SSTP and OpenVPN L3. Since SoftEther VPN Ver 4.31 Build 9727, we added the new function to make each L3 VPN users to use the reserved virtual MAC address and the virtual IP address. This function allows the DHCP server in the remote-access destination network to identify the connected user and to assign reserved IP addresses to each of users respectfully. L3 VPN protocols, such as L2TP/IPsec, SSTP and OpenVPN L3, creates virtual L2/L3 layer-transformation adapter for each of VPN connections which are established to the Virtual Hub on SoftEther VPN Server. A virtual L2/L3 layer-transformation adapter has a virtual MAC address. In the previous versions of SoftEther VPN, virtual MAC addresses are randomly assigned each time when users connect to the VPN Server. There were no solution to assign fixed MAC addresses and IP addresses to each of users. SoftEther VPN Ver 4.31 Build 9727 and later supports the function to fix virtual MAC addresses of every L3 VPN users.

When the user object is using the standard user authentication, you need to write the arbitrary virtual MAC address on the "Note" field on the user object. For example, the "Note" field will have the MAC address format which starts with "MAC:" followed by a 6-bytes ASCII-encoded HEX string, such like "MAC:ae:00:00:00:00:01". We recommend to use the "ae" on the first byte of the MAC address...

https://www.softether.org/5-download/history

Posted: **Sat May 25, 2024 8:58 am**

I have not explained myself well. What you tell me is to set the mac of the users that connect. I got that right. But that MAC and that IP appear without any user connected to the VPN, look:

None of my users have recently connected to the VPN.

I get that virtual IP and that virtual MAC (DA-xx-xx-x) inside my network.

Posted: **Sat May 25, 2024 12:11 pm**

spyfly wrote: ↑
Sat May 25, 2024 12:31 am
My softether configuration does not have its own DHCP but uses the dhcp of the main network.

Then disable SecureNAT and now check the phenomenon.

Posted: **Sat May 25, 2024 2:28 pm**

Why do I have 2 ips? shouldn't it be only 1?

if I disable “secureNAT” the 2 ips disappear. VPN works for users.

if I enable “secureNAT” the 2 ips reappear. VPN works for users.

Posted: **Sat May 25, 2024 2:58 pm**

Case closed. I will refer to this thread to demonstrate why "such config is rarely allowed and in limited extent only".

Posted: **Sat May 25, 2024 8:13 pm**

ok, I will leave SecureNAT disable. But it is curious that if I put it enable I get 2 IPs, shouldn't it be only one?

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