cant prep 2.6.0 pfsense openvpn for 2.7.0

[jsone]

Yep thats it, topology drop down in pfsense 2.6.0 only has 2 options listed for p2p ssl/tls, it has NO options listed for p2p psk. it auto assumes p2p top for psk

<div class="form-group">
<label class="col-sm-2 control-label">
<span>Topology</span>
</label>
<div class="col-sm-10">
<select class="form-control" name="topology" id="topology">
<option value="subnet" selected="">Subnet -- One IP address per client in a common subnet</option><option value="net30">net30 -- Isolated /30 network per client</option>
</select>

	<span class="help-block">Specifies the method used to supply a virtual adapter IP address to clients when using TUN mode on IPv4.<br>Some clients may require this be set to "subnet" even for IPv6, such as OpenVPN Connect (iOS/Android). Older versions of OpenVPN (before 2.0.9) or clients such as Yealink phones may require "net30".</span>
</div>
	
</div>

https://community.openvpn.net/openvpn/wiki/Topology
Topology in OpenVPN

Several network topologies exist for servers configured to accept multiple client connections. These are controlled with the --topology option.
Possible topology choices

These are available options as values to the --topology parameter in --dev tun mode. Each topology is described further in its own section below.

subnet
The recommended topology for modern servers. Note that this is not the current default. Addressing is done by IP & netmask.
net30
This is the old topology for support with Windows clients running 2.0.9 or older clients. This is the default as of OpenVPN 2.3, but not recommended for current use. Each client is allocated a virtual /30, taking 4 IPs per client, plus 4 for the server.
p2p
This topology uses Point-to-Point networking. This is not compatible with Windows clients, though use with non-Windows allows use of the entire subnet (no "lost" IPs.)

[stephenw10]

P2P PSK has been deprecated by OpenVPN. See: https://docs.netgate.com/pfsense/en/latest/vpn/openvpn/configure-server-mode.html#server-mode

Steve

[jsone]

the web ui in 2.6.0 does not allow for p2p ssl/tls because the option for p2p is not in the topology dropdown, so unless someone patched their ui, nobody on 2.6.0 can use p2p unless its psk, i hope this ui bug has been resolved in 2.7.0

[stephenw10]

Peer to peer SSL/TLS is the default server mode in 2.6:

[jsone]

p2p ssl/tls has a toplogy drop down, p2p mode is not in it,
p2p psk has NO topology drop down

whats in your p2p ssl/tls topology drop down? do you have one?

[jsone]

the client override section talks about how these work but im am not sure what were using with psk since theres no option
override settings:
Tunnel Settings
IPv4 Tunnel Network
The virtual IPv4 network or network type alias with a single entry used for private communications between this client and the server expressed using CIDR (e.g. 10.0.8.5/24).
With subnet topology, enter the client IP address and the subnet mask must match the IPv4 Tunnel Network on the server.
With net30 topology, the first network address of the /30 is assumed to be the server address and the second network address will be assigned to the client.

[jsone]

it appears in 2.6.0 p2p psk mode has no topology defined at all
cat /var/etc/openvpn/client1/config.ovpn | grep top
returns nothing

[stephenw10]

Ah, OK. Re-reading here I see what you mean.

In P2P SSL/TLS mode both subnet and /30 topology can be used. I would only choose to use subnet there.

If you choose subnet and then set a subnet size of /30 there can be only one client so all traffic is routed to it in the same way P2P PSK is configured.

If you choose a larger subnet you need a Client Specific Override to reach any subnets behind a connected client. Adding that creates the iroutes OpenVPN needs to route that traffic to the correct client.

Steve

[jsone]

i mentioned before the gateway monitor for open vpn never updates the ip it always assumes .2 which is down with subnet mode, so you are saying id create a custom override to assign a specific ip to the client to resolve this?

[jsone]

https://community.openvpn.net/openvpn/wiki/Topology
"subnet The recommended topology for modern servers. Note that this is not the current default. Addressing is done by IP & netmask. "

what is the default for p2p in openvpn2.5.4? cause i cannot get p2p ssl/tls to route traffic with dot30 or subet defined

p2p psk works fine with no topology defined

[jsone]

@stephenw10 said in cant prep 2.6.0 pfsense openvpn for 2.7.0:

If you choose subnet and then set a subnet size of /30 there can be only one client so all traffic is routed to it in the same way P2P PSK is configured.

gotcha

[jsone]

changing the
setting topology to subnet and
IPv4 Tunnel Network to a /30 instead of the /24
resolved the problem thank you!

[jimp]

There isn't now (nor has there been) a drop-down choice for p2p in topology, it determines that automatically based on the tunnel network size. If you use /30 for the tunnel network it uses configuration options which end up triggering OpenVPN to behave in p2p mode. It's all described in the docs (https://docs.netgate.com/pfsense/en/latest/vpn/openvpn/configure-server-tunnel.html#ipv4-ipv6-tunnel-network)

That said, that also isn't a good migration path as OpenVPN is also doing away with that mode. We found out when working on DCO and hitting issues with that style of connection that OpenVPN upstream has pretty much abandoned that code path and it's likely to go away when they remove static key.

tl;dr: If you want to ensure forward compatibility, follow the recipe I linked and use a full SSL/TLS server setup with overrides and so on, don't deviate from that. Even if you only have one client.

[stephenw10]

In subnet mode the server always shows .2 as gateway. Even if there's a client at .2.

That is used only to route traffic to the OpenVPN daemon. Once there it uses the iroutes to send traffic to the correct client.

In P2P PSK mode there can be only one client so it's doesn't need a topology set. All traffic is always sent to that client.

Steve

[jsone]

@jimp said in cant prep 2.6.0 pfsense openvpn for 2.7.0:

That said, that also isn't a good migration path as OpenVPN is also doing away with that mode. We found out when working on DCO and hitting issues with that style of connection that OpenVPN upstream has pretty much abandoned that code path and it's likely to go away when they remove static key.

completely agree, the right answer is changing our /24 subnets from yester-year with no topology, to /30 with subnet topology mode

[jimp]

No you have that backward. They are removing the p2p style that uses /30 style subnets.

Use /24 (or something larger than /30 at least) plus the overrides.

[jsone]

ok i think im following, while /30 works now it wont once they drop p2p mode

i changed the server to subnet mode with a local network of .0/24
i then added a client specific override for IPv4 Tunnel Network to .2/24 and it gets .2 for a client ip

traffic would not flow until i also copied over/duplicated both IPv4 Local Network/s and IPv4 Remote Network/s to the client override from the server IPv4 Local Network/s and IPv4 Remote Network/s

[stephenw10]

You should only need the remote networks in the CSO. The same local networks can be passed to all clients.

[jimp]

You don't need to manually assign a tunnel network in the overrides, too. It can all work completely dynamic so long as you have the correct local and remote networks filled in.

[jsone]

@jimp said in cant prep 2.6.0 pfsense openvpn for 2.7.0:

You don't need to manually assign a tunnel network in the overrides

for some bizar reason, it was (sometimes) assigning the client .5 or .6 so i had to use the tunnel network in the client override to force it to .2

looks like everything is working great now, thanks for getting me sorted out!