OpenVPN Support Forum

Hi, we ave problem with Ventura 13.1 and openvpn client 3.4.1 4522
When we try to connect openvpn client show this error message:
tun_prop_error: ifconfig addresses are not in the same /30 subnet (topology net30)
We tried to with statment "topology subnet" in .ovpn config file bat it still not working.

Here log messages

[Jan 17, 2023, 12:09:59] PROTOCOL OPTIONS:
cipher: AES-256-GCM
digest: NONE
key-derivation: OpenVPN PRF
compress: LZO_STUB
peer ID: 0
⏎[Jan 17, 2023, 12:09:59] TunPersist: short-term connection scope
⏎[Jan 17, 2023, 12:09:59] TunPersist: new tun context
⏎[Jan 17, 2023, 12:09:59] EVENT: ASSIGN_IP ⏎[Jan 17, 2023, 12:09:59] TUN Error: tun_prop_error: ifconfig addresses are not in the same /30 subnet (topology net30)
⏎[Jan 17, 2023, 12:09:59] EVENT: TUN_SETUP_FAILED tun_prop_error: ifconfig addresses are not in the same /30 subnet (topology net30)⏎[Jan 17, 2023, 12:09:59] EVENT: DISCONNECTED ⏎[Jan 17, 2023, 12:09:59] Client exception in transport_recv: tun_exception: not connected
⏎[Jan 17, 2023, 12:10:02] Raw stats on disconnect:
BYTES_IN : 2241
BYTES_OUT : 1157
PACKETS_IN : 8
PACKETS_OUT : 7
TUN_SETUP_FAILED : 1

Hello,

This is simply a problem with your server configuration. Check on the server if you're using topology net30, and if so, replace that with topology subnet. The whole idea of net30 topology is outdated and people should really be using subnet now. You may be trying to assign addresses to the VPN client that fall outside of the net30 area for this client.

This is more of a server configuration problem, and I am certain this does not normally happen on our commercial products OpenVPN Access Server or OpenVPN Cloud, so this is apparently an open source OpenVPN configuration. And in that case, I suggest to go through that configuration, and consider switching to subnet topology, as net30 topology is outdated and also something that will likely disappear in the future.

Kind regards,
Johan

Hi Johan,

where/How we could change the net30 topology to subnet?
I don't see that option in the Asus router config neither in the ovpn file; however, I can see in my logs that I'm using net30 like @next_ICT

Thanks!

Hello,

I'm afraid I don't know that. Whenever a router manufacturer chooses to implement OpenVPN, it's up to them to figure out how to expose configuration options to the user. Whenever a device manufacturer chooses to implement open source OpenVPN, they assume responsibility for supporting their particular implementation of it. So I'd suggest to check with Asus what their recommended solution for this issue is.

Kind regards,
Johan