ifconfig addresses are not in same /30 subnet

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next_ICT
OpenVpn Newbie
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Joined: Tue Jan 17, 2023 11:19 am

ifconfig addresses are not in same /30 subnet

Post by next_ICT » Tue Jan 17, 2023 11:28 am

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

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openvpn_inc
OpenVPN Inc.
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Joined: Tue Feb 16, 2021 10:41 am

Re: ifconfig addresses are not in same /30 subnet

Post by openvpn_inc » Fri Feb 03, 2023 12:28 pm

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 The whole idea of net30 topology is outdated and people should really be using subnet now.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that case, I suggest to go through that configuration, and consider switching to subnet topology, as net30 topology is outdated and also something that will likely disappear in the future.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
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fkarausch2@gmail.com
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Joined: Tue Jan 31, 2023 9:58 pm

Re: ifconfig addresses are not in same /30 subnet

Post by fkarausch2@gmail.com » Sun Feb 05, 2023 6:32 pm

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!

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openvpn_inc
OpenVPN Inc.
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Joined: Tue Feb 16, 2021 10:41 am

Re: ifconfig addresses are not in same /30 subnet

Post by openvpn_inc » Mon Feb 20, 2023 9:46 am

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
Image OpenVPN Inc.
Answers provided by OpenVPN Inc. staff members here are provided on a voluntary best-effort basis, and no rights can be claimed on the basis of answers posted in this public forum. If you wish to get official support from OpenVPN Inc. please use the official support ticket system: https://openvpn.net/support

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