L2TP EncapsulationType=ip not starting

[Tr4sK]

systemd version the issue has been seen with

254

Used distribution

debian

Linux kernel version used

6.6.13+bpo-amd64

CPU architectures issue was seen on

x86_64

Component

systemd-networkd

Expected behaviour you didn't see

I'm able to create a tunnel with ip l2tp but cannot make it work with an l2tp netdev.

[admin@Mkt] /interface/l2tp-ether> print detail
Flags: X - disabled; D - dynamic; R - running; u - unmanaged
 0   Ru name="l2tp-ether1" mtu=auto actual-mtu=1418 connect-to=xx.xx.xx.35
        mac-address=XX:XX:XX:4C:8E:05 use-ipsec=no ipsec-secret=""
        allow-fast-path=yes l2tp-proto-version=l2tpv3-ip circuit-id=""
        cookie-length=0 digest-hash=md5 use-l2-specific-sublayer=yes
        local-address=xx.xx.xx.201 local-tunnel-id=201 local-session-id=201
        remote-tunnel-id=201 remote-session-id=201 unmanaged-mode=yes
root@nms:~# ip l2tp add tunnel tunnel_id 201 peer_tunnel_id 201 encap ip local xx.xx.xx.35 remote xx.xx.xx.201
root@nms:~# ip l2tp add session name l2tp-sess tunnel_id 201 session_id peer_session_id 201

root@nms:~# ip l2tp show tunnel
Tunnel 201, encap IP
  From xx.xx.xx.35 to xx.xx.xx.201
root@nms:~# ip l2tp show session
Session 201 in tunnel 201
  Peer session 201, tunnel 201
  interface name: l2tp-sess-mkt
  offset 0, peer offset 0


23: l2tp-sess-mkt: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1458 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether XX:XX:XX:0b:8e:12 brd ff:ff:ff:ff:ff:ff
    inet 192.168.88.167/24 metric 1024 brd 192.168.88.255 scope global dynamic l2tp-sess-mkt
       valid_lft 599sec preferred_lft 599sec


root@nms:~# networkctl status l2tp-sess-mkt
● 23: l2tp-sess-mkt
                     Link File: /usr/lib/systemd/network/99-default.link
                  Network File: /etc/systemd/network/l2tp.network
                         State: routable (configured)
                  Online state: unknown
                          Type: l2tpeth
              Hardware Address: XX:XX:XX:0b:8e:12
                           MTU: 1458 (max: 65535)
                         QDisc: fq_codel
  IPv6 Address Generation Mode: none
      Number of Queues (Tx/Rx): 1/1
                       Address: 192.168.88.167 (DHCP4 via 192.168.88.1)
             Activation Policy: up
           Required For Online: no
               DHCP4 Client ID: IAID:0x456deb8c/DUID
                  Connected To: FDH on port bridge/l2tp.nms

mai 09 02:50:13 nms systemd-networkd[649]: l2tp-sess-mkt: link_check_ready(): IPv4LL:>
mai 09 02:50:13 nms systemd-networkd[649]: l2tp-sess-mkt: State changed: configuring >
mai 09 02:50:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Invoking callback >
mai 09 02:50:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Successfully proce>
mai 09 02:51:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Invoking callback >
mai 09 02:51:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Successfully proce>
mai 09 02:52:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Invoking callback >
mai 09 02:52:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Successfully proce>
mai 09 02:53:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Invoking callback >
mai 09 02:53:41 nms systemd-networkd[649]: l2tp-sess-mkt: LLDP Rx: Successfully proce>

root@nms:~# cat /etc/systemd/network/l2tp.network
[Match]
Name=!cesure
Type=l2tpeth

[Network]
DHCP=ipv4
LinkLocalAddressing=no
IPv6LinkLocalAddressGenerationMode=none

[DHCPv4]
UseDNS=no
UseGateway=no
UseNTP=no

[Link]
RequiredForOnline=no

Unexpected behaviour you saw

cat /etc/systemd/network/mkt.netdev
[NetDev]
Name=l2tp-mkt
Kind=l2tp

[L2TP]
TunnelId=201
PeerTunnelId=201
Remote=xx.xx.xx.201
Local=xx.xx.xx.35
EncapsulationType=ip

[L2TPSession]
Name=l2tp-sess-mkt
SessionId=201
PeerSessionId=201

root@nms:~# journalctl -b0 |grep -E "mkt|l2tp"
mai 09 01:47:29 nms kernel: l2tp_core: L2TP core driver, V2.0
mai 09 01:47:29 nms kernel: l2tp_netlink: L2TP netlink interface
mai 09 01:47:29 nms systemd-networkd[649]: l2tp-mkt: loaded "l2tp"
mai 09 01:47:29 nms kernel: l2tp_ip: L2TP IP encapsulation support (L2TPv3)
mai 09 01:47:29 nms systemd-networkd[649]: l2tp-mkt: loaded "l2tp"

root@nms:~# ls -la /etc/systemd/network/fdh.net*
-rw-r----- 1 root systemd-network 200  9 mai   02:27 /etc/systemd/network/fdh.netdev
-rw-r--r-- 1 root systemd-network 187  9 mai   00:43 /etc/systemd/network/fdh.network




root@nms:~# ip l2tp show tunnel
empty

root@nms:~# ip l2tp show session
empty

Steps to reproduce the problem

Create a tunnel on some device and create a netdev.

Additional program output to the terminal or log subsystem illustrating the issue

Full log here : https://paste.sh/fiKH_IFO#g9yTHCsiJYj-bccB3l3HP8uo