NixOS Networking

Sender	Message	Time
5 Jun 2021
mutantmell	In reply to @hexa:lossy.network mutantmell: openwrt will be easy, nixwrt might be something you want to look into thanks for the pointer!	22:52:14
ElvishJerricco	$ networkctl status wlan0 ● 3: wlan0 Link File: /nix/store/i3kbvbm0rib0habk88ybm9xpqpnj1s8x-systemd-247.2/lib/systemd/network/99-default.link Network File: /etc/systemd/network/40-wlan0.network Type: wlan State: enslaved (failed) Path: platform-fe300000.mmcnr Driver: brcmfmac HW Address: dc:a6:32:fe:7a:34 (Raspberry Pi Trading Ltd) MTU: 1500 (min: 68, max: 1500) QDisc: fq_codel Master: br0 IPv6 Address Generation Mode: none WiFi access point: My Pi Network (00:00:00:00:00:00) Queue Length (Tx/Rx): 1/1 Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Could not join netdev: Device does not allow enslaving to a bridge. Operation not supported Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Failed Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Link UP Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Gained carrier So this is the networkctl status of my wlan0 interface on the rpi that I set up as an access point yesterday. The network all functions like there's nothing wrong, but there it says it's "failed". Why is that?	23:50:48
Zhaofeng Li	You typically can't put wireless interfaces into a bridge	23:53:05
ElvishJerricco	Zhaofeng Li: Well it works. I have hostapd on wlan0, and my other devices can connect to it as a wifi network, and the bridge with eth0 must be working because those devices can reach the internet.	23:54:04
Zhaofeng Li	You are doing routing instead of bridging	23:56:00
Zhaofeng Li	Care to explain your setup again?	23:56:34
ElvishJerricco	Zhaofeng Li: I don't have a dhcp server or anything on this pi though	23:56:38
ElvishJerricco	One sec...	23:57:02
ElvishJerricco	On my pi, I have this: `networking.bridges.br0.interfaces = ["eth0" "wlan0"]; services.hostapd = { enable = true; interface = "wlan0"; hwMode = "g"; ssid = "My Pi Network"; wpaPassphrase = "foobarbaz"; extraConfig = '' disable_pmksa_caching=0 wpa_pairwise=CCMP rsn_pairwise=CCMP bridge=br0 ''; };`	23:59:01
ElvishJerricco	eth0 leads back to enp4s0 on my desktop, which is running a dhcp server with its wifi interface as the wan	23:59:30
ElvishJerricco	On the desktop: let wan = "wlp5s0"; lan = "enp4s0"; in { services.dhcpd4 = { interfaces = [ lan ]; enable = true; extraConfig = '' subnet 192.168.3.0 netmask 255.255.255.0 { option subnet-mask 255.255.255.0; option broadcast-address 192.168.3.255; option routers 192.168.3.1; option domain-name-servers 8.8.8.8, 8.8.4.4; range 192.168.3.100 192.168.3.200; } ''; }; networking = { networkmanager.unmanaged = [ lan ]; interfaces = { ${lan} = { ipv4.addresses = [{ address = "192.168.3.1"; prefixLength = 24; }]; }; }; nat = { enable = true; externalInterface = wan; internalIPs = [ "192.168.3.0/24" ]; internalInterfaces = [ lan ]; }; }; }	23:59:58
6 Jun 2021
ElvishJerricco	Woops, pi also has this: `networking.useDHCP = false; networking.interfaces.eth0.useDHCP = false; networking.interfaces.wlan0.useDHCP = false; networking.interfaces.br0.useDHCP = true;`	00:00:33
Zhaofeng Li	Oh wait, apparently I can't read and you are using it as an AP 😐️ Then it should work and systemd-networkd was probably trying to bridge the interface before hostapd started	00:00:34
ElvishJerricco	Ah. How would I mess with the unit files to ensure proper ordering?	00:00:59
Zhaofeng Li	I don't think there's a clean solution to this one unfortunately. You can keep it unbridged in networkd and add a service that runs brctl after hostapd has started	00:02:27
Zhaofeng Li	Oh it's a long-standing known issue: https://github.com/systemd/systemd/issues/936	00:03:05
Zhaofeng Li	So yeah, no clean solution :/	00:03:26
ElvishJerricco	Well darn	00:05:21
hexa	ElvishJerricco: hostapd can put stuff into a bridge, not sure how it achieves that, but networkd can't	00:08:32
hexa	have to read hostapd code for that I guess	00:08:41
hexa	or yeah, might be a timing issue	00:08:48
ElvishJerricco	hexa: So I shouldn't have wlan0 in the br0.interfaces = [...] line?	00:09:11
hexa	A WIFI interface needs to be set in 4addr mode before it's added to a bridge.	00:09:19
hexa	that's probably it	00:09:23
hexa	iw dev $name set 4addr on	00:09:33
hexa	sadly networkd is free of hooks :)	00:09:42
hexa	services.hostapd.serviceConfig.ExecStartPost = "systemctl restart systemd-networkd";	00:10:34
hexa	should probably hackfix your stuff :D	00:10:42
ElvishJerricco	Well, simply removing it from the br0.interfaces makes it "degraded" instead of "failed", and hostapd does seem to have added it to the bridge itself as the wifi still works	00:13:37
Zhaofeng Li	For the degraded thing, use LinkLocalAddressing=no to make networkd not try to add addresses to it at all	00:16:30

In reply to @hexa:lossy.network
mutantmell: openwrt will be easy, nixwrt might be something you want to look into

thanks for the pointer!

$ networkctl status wlan0
● 3: wlan0                                                                                                                   
                     Link File: /nix/store/i3kbvbm0rib0habk88ybm9xpqpnj1s8x-systemd-247.2/lib/systemd/network/99-default.link
                  Network File: /etc/systemd/network/40-wlan0.network                                                        
                          Type: wlan                                                                                         
                         State: enslaved (failed)                                                                            
                          Path: platform-fe300000.mmcnr                                                                      
                        Driver: brcmfmac                                                                                     
                    HW Address: dc:a6:32:fe:7a:34 (Raspberry Pi Trading Ltd)                                                 
                           MTU: 1500 (min: 68, max: 1500)                                                                    
                         QDisc: fq_codel                                                                                     
                        Master: br0                                                                                          
  IPv6 Address Generation Mode: none                                                                                         
             WiFi access point: My Pi Network (00:00:00:00:00:00)                                                            
          Queue Length (Tx/Rx): 1/1                                                                                          

Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Could not join netdev: Device does not allow enslaving to a bridge. Operation not supported
Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Failed
Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Link UP
Jun 05 23:47:15 nixos systemd-networkd[659]: wlan0: Gained carrier

So this is the networkctl status of my wlan0 interface on the rpi that I set up as an access point yesterday. The network all functions like there's nothing wrong, but there it says it's "failed". Why is that?