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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I have an issue with two machines connected via GRE exchanging routes via OSPF.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Both server have wireguard tunnels to the same external endpoints, so a request from an endpoint may come in through tunnel 1 to server A, forwarded to wan and the reply may enter through server
B and tunnel 2 back to the endpoint.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">All routes are exported to a custom kernel routing table by bird2.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">For example:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US" style="font-size:11.0pt">Server A’s wireguard network is: 10.100.0.0/24<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US" style="font-size:11.0pt">GRE IP of server A is 10.0.1.1<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US" style="font-size:11.0pt">GRE IP of server B is 10.0.1.2<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">The problem I’m facing is, that bird2 respects the local interface route of server A but on server B, while the wireguard interface also having the same subnet (10.100.0.0/24), bird2 adds a route
which says the nexthop for this subnet is through 10.0.1.1 (the GRE tunnel).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I only managed to solve this by excluding the wireguard subnet with an export filter. What I am expecting (or actually want) is bird respecting the local interface route on both servers and only,
if a tunnel goes offline (no peer connected), changes the route through the GRE tunnel. I’m not sure, whether a part of this solution can be done solely by using bird. I know that wireguard tunnels do not have states, so post-up/post-down stuff is out of the
question.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Any solutions?<o:p></o:p></span></p>
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