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I love wireguard but my one gripe with it is that its not a true data link layer. You have to give it routing information through an out of band mechanism “Allo

I love wireguard but my one gripe with it is that its not a true data link layer. You have to give it routing information through an out of band mechanism “AllowedIPs.” One downside is that you can’t have two peers that act as general routers on the same wireguard network. With Ethernet, you can have multiple nodes in the same subnet acting as generic routers, it’s just a matter of sending IP packets to that host. I hope someday wireguard addresses this issue and makes itself fully transparent as a data link layer.

mercora 5y ago
i just wish i could control the routing via routing tables instead, making dynamic routing decisions possible without specialized software that is able to manipulate it.
- 3np 5y ago
  You can. You just need to use the right tools. See my uncle comment.
  - mercora 5y ago
    just so you know, your assumption i am not using the right tools feels almost insulting to me considering i made no claim about any tooling used. i am using systemd-networkd to setup networking anywhere, i never touch wg-quick because it is no fit for my use cases. i have multiple routing tables and do policy routing and i would really like to have the "via" in the routing tables to have a meaning to wireguards crypto routing thing. i.e. i want to be able to set "AllowedIPs" based upon the routing table very similar to reverse path filtering. i know i can setup multiple interfaces with multiple keys to exchange and multiple ports to set and to make sure every client that needs to is kept in sync.... but it would be much nicer if i could handle it like an ip-ip tunnel and make routing decisions with software build for this purpose.
  - deleted 5y ago
    [deleted]
octoberfranklin 5y ago
Wireguard is not a link layer (layer 2) tunnel; it is a network (layer 3) tunnel. It operates at the IP layer. You cannot use Wireguard with any non-IP layer3. AllowedIPs can be disabled if you want; just set it to 0.0.0.0/0. AllowedIPs is needed because netfilter can't "see" which public key an inbound packet is coming from, so by the time a packet gets to netfilter it's too late to accept/reject based on which peer sent it to us.
- zekica 5y ago
  This is less important although useful in some cases. The more important thing is outbound - since Wireguard is layer 3, in the routing table you can't specify a peer to send the packet to like you can with ethernet, and it has to choose one using AllowedIPs.
  - 3np 5y ago
    Why not just split the peers up over separate wg interfaces?
- _dh54 5y ago
  > Wireguard is not a link layer (layer 2) Yes but UI wise it presents itself as one, since it’s acts as an interface. The fact that it is not a true data link layer is the basis of my comment. > AllowedIPs can be disabled if you want; just set it to 0.0.0.0/0. Only one peer is allowed to use 0.0.0.0/0 for AllowedIPs
  - octoberfranklin 5y ago
    > Only one peer is allowed to use 0.0.0.0/0 for AllowedIPs This is simply incorrect. You can have two peers with the same AllowedIP; you just have to put them on separate interfaces (wg0 and wg1 for example). This is for exactly the same reason that a routing table can only have one default entry. If you want two default entries, make two routing tables. > Yes but UI wise it presents itself as one No, it doesn't present itself as one. > since it’s acts as an interface So does /dev/net/tun, which is definitely not a layer 2 interface either.
3np 5y ago
> You have to give it routing information through an out of band mechanism “AllowedIPs.” One downside is that you can’t have two peers that act as general routers on the same wireguard network This is a common misconception, due to that this is the way wg-quick works (unfortunately IMO; presumably to make it easier, and I guess wg-quick was never meant for people with advanced needs). On a lower level, AllowedIPs is really just "allowed IPs", and does no routing. You can have multiple active peers with overlapping AllowedIPs. If you set up the tunnel through other means, you can make your own routes. For example in systemd-networkd, see `RouteTable` under the `[WireguardPeer]` section of systemd.netdev(5). (This was unfortunately broken for a brief while in systemd in Jan, but should now be fixed again: https://github.com/systemd/systemd/pull/22136 https://github.com/systemd/systemd/pull/22136. If it's not clear from the link, old and current behavior are that no routes are added unless RouteTable is explicitly set) You should also be able to set it up manually and then add routes, policies and rules manually however you would otherwise. (You're of course right on the protocol layer, but that is not the cause of the problem you want to solve)
- rfoo 5y ago
  Are you sure what you described works? Last I tried it didn't work, and this is explicitly stated on wireguard.com: > In other words, when sending packets, the list of allowed IPs behaves as a sort of routing table, and when receiving packets, the list of allowed IPs behaves as a sort of access control list. > This is what we call a Cryptokey Routing Table: the simple association of public keys and allowed IPs. Which is, I believe, also why zx2c4 called to revert the whole systemd-networkd feature. I would really want it to work as it would simplify my network configuration by a bit. Please share a working example if you are able to make it work, thanks! Last I tried that I used iproute 2 to manually setup interfaces, use wg setconf to load WireGuard configurations. So I don't think it's my tool to blame.
  - 3np 5y ago
    > Are you sure what you described works? Last I tried it didn't work, and this is explicitly stated on wireguard.com: If we're talking simply about decoupling routing from AllowedIPs, yes, using that right now and set it up several times. For redundant routers, see below. > > In other words, when sending packets, the list of allowed IPs behaves as a sort of routing table This does seem in conflict with my understanding... Depending on exactly what devil-details go into that "sort of", of course. Not deep enough into it to tell you, though. > Which is, I believe, also why zx2c4 called to revert the whole systemd-networkd feature. Rather the opposite AIUI; To allow for setting routes explicitly (which introducing the wg-quick behavior broke[0]). What started making it click for me was this ArchWiki section[1]. The discussion under this GH issue may also provide some pointers[2]. Also [3]. IIRC I did get multiple outbound redundant routers with failover in the end. There may be WG-specific gremlins I glanced over but ascribed it to not fully grokking the Linux IP stack and issues with *tables in general at the time - the goal I had is hairy enough without Wireguard in the mix. Please report back here on your progress if you have the time :) [0]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003955 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003955 [1]: https://wiki.archlinux.org/title/WireGuard#systemd-networkd:_routing_all_traffic_over_WireGuard https://wiki.archlinux.org/title/WireGuard#systemd-networkd:... [2]: https://github.com/systemd/systemd/issues/14176 https://github.com/systemd/systemd/issues/14176 [3]: https://www.eisfunke.com/article/docker-wireguard-systemd.html https://www.eisfunke.com/article/docker-wireguard-systemd.ht... ----- EDIT: Went back to take a look and I never did get proper HA routing sorted - ended up "solving" it with a script regularly checking reachability and bringing routes up/down accordingly. No need to bring the actual WG interfaces or IP assignments up/down for that, though.
nikita2206 5y ago
Sounds like you’re either already a Zerotier user or would be happy to discover their product.

mercora 5y ago

i just wish i could control the routing via routing tables instead, making dynamic routing decisions possible without specialized software that is able to manipulate it.

3np 5y ago
You can. You just need to use the right tools. See my uncle comment.
- mercora 5y ago
  just so you know, your assumption i am not using the right tools feels almost insulting to me considering i made no claim about any tooling used. i am using systemd-networkd to setup networking anywhere, i never touch wg-quick because it is no fit for my use cases. i have multiple routing tables and do policy routing and i would really like to have the "via" in the routing tables to have a meaning to wireguards crypto routing thing. i.e. i want to be able to set "AllowedIPs" based upon the routing table very similar to reverse path filtering. i know i can setup multiple interfaces with multiple keys to exchange and multiple ports to set and to make sure every client that needs to is kept in sync.... but it would be much nicer if i could handle it like an ip-ip tunnel and make routing decisions with software build for this purpose.
- deleted 5y ago
  [deleted]

octoberfranklin 5y ago

Wireguard is not a link layer (layer 2) tunnel; it is a network (layer 3) tunnel. It operates at the IP layer. You cannot use Wireguard with any non-IP layer3. AllowedIPs can be disabled if you want; just set it to 0.0.0.0/0. AllowedIPs is needed because netfilter can't "see" which public key an inbound packet is coming from, so by the time a packet gets to netfilter it's too late to accept/reject based on which peer sent it to us.

zekica 5y ago
This is less important although useful in some cases. The more important thing is outbound - since Wireguard is layer 3, in the routing table you can't specify a peer to send the packet to like you can with ethernet, and it has to choose one using AllowedIPs.
- 3np 5y ago
  Why not just split the peers up over separate wg interfaces?
_dh54 5y ago
> Wireguard is not a link layer (layer 2) Yes but UI wise it presents itself as one, since it’s acts as an interface. The fact that it is not a true data link layer is the basis of my comment. > AllowedIPs can be disabled if you want; just set it to 0.0.0.0/0. Only one peer is allowed to use 0.0.0.0/0 for AllowedIPs
- octoberfranklin 5y ago
  > Only one peer is allowed to use 0.0.0.0/0 for AllowedIPs This is simply incorrect. You can have two peers with the same AllowedIP; you just have to put them on separate interfaces (wg0 and wg1 for example). This is for exactly the same reason that a routing table can only have one default entry. If you want two default entries, make two routing tables. > Yes but UI wise it presents itself as one No, it doesn't present itself as one. > since it’s acts as an interface So does /dev/net/tun, which is definitely not a layer 2 interface either.

3np 5y ago

> You have to give it routing information through an out of band mechanism “AllowedIPs.” One downside is that you can’t have two peers that act as general routers on the same wireguard network This is a common misconception, due to that this is the way wg-quick works (unfortunately IMO; presumably to make it easier, and I guess wg-quick was never meant for people with advanced needs). On a lower level, AllowedIPs is really just "allowed IPs", and does no routing. You can have multiple active peers with overlapping AllowedIPs. If you set up the tunnel through other means, you can make your own routes. For example in systemd-networkd, see `RouteTable` under the `[WireguardPeer]` section of systemd.netdev(5). (This was unfortunately broken for a brief while in systemd in Jan, but should now be fixed again: https://github.com/systemd/systemd/pull/22136 https://github.com/systemd/systemd/pull/22136. If it's not clear from the link, old and current behavior are that no routes are added unless RouteTable is explicitly set) You should also be able to set it up manually and then add routes, policies and rules manually however you would otherwise. (You're of course right on the protocol layer, but that is not the cause of the problem you want to solve)

rfoo 5y ago
Are you sure what you described works? Last I tried it didn't work, and this is explicitly stated on wireguard.com: > In other words, when sending packets, the list of allowed IPs behaves as a sort of routing table, and when receiving packets, the list of allowed IPs behaves as a sort of access control list. > This is what we call a Cryptokey Routing Table: the simple association of public keys and allowed IPs. Which is, I believe, also why zx2c4 called to revert the whole systemd-networkd feature. I would really want it to work as it would simplify my network configuration by a bit. Please share a working example if you are able to make it work, thanks! Last I tried that I used iproute 2 to manually setup interfaces, use wg setconf to load WireGuard configurations. So I don't think it's my tool to blame.
- 3np 5y ago
  > Are you sure what you described works? Last I tried it didn't work, and this is explicitly stated on wireguard.com: If we're talking simply about decoupling routing from AllowedIPs, yes, using that right now and set it up several times. For redundant routers, see below. > > In other words, when sending packets, the list of allowed IPs behaves as a sort of routing table This does seem in conflict with my understanding... Depending on exactly what devil-details go into that "sort of", of course. Not deep enough into it to tell you, though. > Which is, I believe, also why zx2c4 called to revert the whole systemd-networkd feature. Rather the opposite AIUI; To allow for setting routes explicitly (which introducing the wg-quick behavior broke[0]). What started making it click for me was this ArchWiki section[1]. The discussion under this GH issue may also provide some pointers[2]. Also [3]. IIRC I did get multiple outbound redundant routers with failover in the end. There may be WG-specific gremlins I glanced over but ascribed it to not fully grokking the Linux IP stack and issues with *tables in general at the time - the goal I had is hairy enough without Wireguard in the mix. Please report back here on your progress if you have the time :) [0]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003955 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003955 [1]: https://wiki.archlinux.org/title/WireGuard#systemd-networkd:_routing_all_traffic_over_WireGuard https://wiki.archlinux.org/title/WireGuard#systemd-networkd:... [2]: https://github.com/systemd/systemd/issues/14176 https://github.com/systemd/systemd/issues/14176 [3]: https://www.eisfunke.com/article/docker-wireguard-systemd.html https://www.eisfunke.com/article/docker-wireguard-systemd.ht... ----- EDIT: Went back to take a look and I never did get proper HA routing sorted - ended up "solving" it with a script regularly checking reachability and bringing routes up/down accordingly. No need to bring the actual WG interfaces or IP assignments up/down for that, though.

nikita2206 5y ago

Sounds like you’re either already a Zerotier user or would be happy to discover their product.