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From: "Rémi Lapeyre" <remi.lapeyre@lenstra.fr>
To: wireguard@lists.zx2c4.com
Subject: Adding 2FA to WireGuard
Date: Thu, 12 Sep 2019 14:01:24 -0700
Message-ID: <CAFsReqSUQYthBTr4o7HQQGdNUgzA33i9hAoJ_UieNUzJbB=hLA@mail.gmail.com> (raw)

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Hi everybody! We are using WireeGuard on Mac and Linux which works great
but for
compliance purpose, we would like to be able to add an OTP challenge on
connection.

I've been looking at the archive of the mailing list and at the various
projects
built around WireGuard and started writing an implementation based on the
idea
from https://lists.zx2c4.com/pipermail/wireguard/2017-September/001741.html:

> Alternatively, you could do OTP in-band, in order to authorize that
> public key for a certain window of time before inactivity. In this
> scheme, you'd disallow access to the network segment based on firewall
> rules until a certain in-band challenge is made -- perhaps by
> contacting a certain sandboxed server and answering an OTP challenge
> there

My current implementation (I plan to publish it under MIT license once it's
ready) has a Python server on the WireGuard server bound to the wg interface
that add an IPTable rule to allow the traffic for a given amount of time
when
a TOTP is received over TCP. Here are some details

  - The TOTP is bound to the internal tunnel IP address so the IP address
that
  opens the TCP connection is used to identify the user, as thee packet
must
  have been decrypted, it seems to me that there is no way to spoof this.

  - A small text protocol let the user log-in, log-out and read the status
of the
  connection.

The client needs to send the TOTP just after connecting to the server, for
which
I had hoped to use the "PostUp" field of wg-quick.

{Post,Pre}-{Up,Down} seems to be only available on wg-quick for now but we
are
using the wireguard-apple client so I have a few questions:

  1. Is the absence of support {Post,Pre}-{Up,Down} in wireguard-apple on
  purpose or would a patch to add this welcomed?

  2. Is this way to do the OTP authentication sound?

  3. I've seen that TunSafe has added an extension to the WireGuard
protocol so
  the TOTP auth would not be shared by an attacker that succeded to connect
when
  the user is already connected. This seems like a good idea to do, what
are your
  thougts about this? Would you recommend against my "easier"
implementation?

  4. I know that TunSafe was strongly advised against when it was
closed-source.
  Now that it is AGPL code, is it still the case?

One more thing, to simplify the deployment of WireGuard, I would like to
propose
a change in the way the MacOS client import WireGuard configurations from a
file.

Our current flow is "Please open the WireGuard app, click on create Tunnel,
give
it a name, paste this configuration underneath what's already written, hit
save
and send us your public key". It gives a lot of oportunity to the user to
mistype something and make changing the configuration cumbersome ("Edit the
tunnel, don't touch the `[Interface]` part but replace what's underneath by
this") so I would like to be able to send to the user a configuration file
with
the PrivateKey missing and have the WireGuard client generate one on the
fly but
this currently gives an error "Interface’s private key is required". Would
sending a patch for this be welcomed too?


Thanks for taking the time to help me, I look forward to contribute to
WireGuard :)

Rémi

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<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body><div style="font-family:Helvetica,Arial;font-size:13px"><div style="margin:0px">Hi everybody! We are using WireeGuard on Mac and Linux which works great but for </div><div style="margin:0px">compliance purpose, we would like to be able to add an OTP challenge on connection.</div><div style="margin:0px"><br></div><div style="margin:0px">I&#39;ve been looking at the archive of the mailing list and at the various projects</div><div style="margin:0px">built around WireGuard and started writing an implementation based on the idea</div><div style="margin:0px">from <a href="https://lists.zx2c4.com/pipermail/wireguard/2017-September/001741.html">https://lists.zx2c4.com/pipermail/wireguard/2017-September/001741.html</a>:</div><div style="margin:0px"><br></div><div style="margin:0px">&gt; Alternatively, you could do OTP in-band, in order to authorize that</div><div style="margin:0px">&gt; public key for a certain window of time before inactivity. In this</div><div style="margin:0px">&gt; scheme, you&#39;d disallow access to the network segment based on firewall</div><div style="margin:0px">&gt; rules until a certain in-band challenge is made -- perhaps by</div><div style="margin:0px">&gt; contacting a certain sandboxed server and answering an OTP challenge</div><div style="margin:0px">&gt; there</div><div style="margin:0px"><br></div><div style="margin:0px">My current implementation (I plan to publish it under MIT license once it&#39;s </div><div style="margin:0px">ready) has a Python server on the WireGuard server bound to the wg interface</div><div style="margin:0px">that add an IPTable rule to allow the traffic for a given amount of time when</div><div style="margin:0px">a TOTP is received over TCP. Here are some details</div><div style="margin:0px"><br></div><div style="margin:0px">  - The TOTP is bound to the internal tunnel IP address so the IP address that</div><div style="margin:0px">  opens the TCP connection is used to identify the user, as thee packet must </div><div style="margin:0px">  have been decrypted, it seems to me that there is no way to spoof this.</div><div style="margin:0px"><br></div><div style="margin:0px">  - A small text protocol let the user log-in, log-out and read the status of the </div><div style="margin:0px">  connection.</div><div style="margin:0px"><br></div><div style="margin:0px">The client needs to send the TOTP just after connecting to the server, for which</div><div style="margin:0px">I had hoped to use the &quot;PostUp&quot; field of wg-quick.</div><div style="margin:0px"><br></div><div style="margin:0px">{Post,Pre}-{Up,Down} seems to be only available on wg-quick for now but we are</div><div style="margin:0px">using the wireguard-apple client so I have a few questions:</div><div style="margin:0px"><br></div><div style="margin:0px">  1. Is the absence of support {Post,Pre}-{Up,Down} in wireguard-apple on</div><div style="margin:0px">  purpose or would a patch to add this welcomed?</div><div style="margin:0px"><br></div><div style="margin:0px">  2. Is this way to do the OTP authentication sound?</div><div style="margin:0px"><br></div><div style="margin:0px">  3. I&#39;ve seen that TunSafe has added an extension to the WireGuard protocol so</div><div style="margin:0px">  the TOTP auth would not be shared by an attacker that succeded to connect when</div><div style="margin:0px">  the user is already connected. This seems like a good idea to do, what are your </div><div style="margin:0px">  thougts about this? Would you recommend against my &quot;easier&quot; implementation?</div><div style="margin:0px"><br></div><div style="margin:0px">  4. I know that TunSafe was strongly advised against when it was closed-source.</div><div style="margin:0px">  Now that it is AGPL code, is it still the case?</div><div style="margin:0px"><br></div><div style="margin:0px">One more thing, to simplify the deployment of WireGuard, I would like to propose</div><div style="margin:0px">a change in the way the MacOS client import WireGuard configurations from a file.</div><div style="margin:0px"><br></div><div style="margin:0px">Our current flow is &quot;Please open the WireGuard app, click on create Tunnel, give </div><div style="margin:0px">it a name, paste this configuration underneath what&#39;s already written, hit save</div><div style="margin:0px">and send us your public key&quot;. It gives a lot of oportunity to the user to</div><div style="margin:0px">mistype something and make changing the configuration cumbersome (&quot;Edit the </div><div style="margin:0px">tunnel, don&#39;t touch the `[Interface]` part but replace what&#39;s underneath by </div><div style="margin:0px">this&quot;) so I would like to be able to send to the user a configuration file with</div><div style="margin:0px">the PrivateKey missing and have the WireGuard client generate one on the fly but</div><div style="margin:0px">this currently gives an error &quot;Interface’s private key is required&quot;. Would</div><div style="margin:0px">sending a patch for this be welcomed too?</div><div style="margin:0px"><br></div><div style="margin:0px"><br></div><div style="margin:0px">Thanks for taking the time to help me, I look forward to contribute to WireGuard :)</div><div style="margin:0px"><br></div><div style="margin:0px">Rémi</div><div><br></div></div></body></html>

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Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12 21:01 Rémi Lapeyre [this message]
2019-09-13 12:49 ` Nico Schottelius
2019-09-13 13:17   ` Rémi Lapeyre
2019-09-13 13:22     ` Nico Schottelius
2019-09-15 16:46 ` Rene 'Renne' Bartsch, B.Sc. Informatics

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