On 9/23/20 7:07 AM, Stephen John Smoogen wrote: > On Wed, 23 Sep 2020 at 04:33, Carlos Lopez <clopmz at outlook.com> wrote: > >> Hi all, >> >> >> With SystemD, how can I make certain service dependent on certain network >> interfaces being up? >> >> For example, I have an 802.1ad bond interface I need to wait on for being >> up (this interface has no ip address assigned, it is used to capture >> networks packets with a tcpdump’s script). Every time this service fails >> because bond interface is not up. >> >> >> >> I have configured the service as: >> >> >> [Unit] >> >> Description=tcpdump capture script >> >> After=network.target >> >> Wants=network-online.target >> >> >> >> But it doesn’t work …. Any tip or trick? >> >> >> > > So the network just calls the scripts and exits so they can take a while to > get working. I think this website covers what you want to do > > https://unix.stackexchange.com/questions/257888/systemd-wait-for-network-interface-to-be-up-before-running-service > > systemctl list-units --no-pager | grep subsystem-net > > Then look for the device which matches the one you are listening to. Change > the After=network.target to > > > BindsTo=sys-devices-virtual-net-<device>.device > After=sys-devices-virtual-net-<device>.device > > where <device> is the interface you found (aka eth2, br9, bond0 etc) Hmm, there seems to be several layers here. I think sys-devices-<device>.device is "started" when <device> appears in the kernel: Sep 23 19:37:25 kernel: virtio_net virtio0 ens3: renamed from eth0 # systemctl status sys-subsystem-net-devices-ens3.device ● sys-subsystem-net-devices-ens3.device - Virtio network device Loaded: loaded Active: active (plugged) since Wed 2020-09-23 19:37:25 MDT This is not what most people would consider "up" - i.e. have an IP address. ens3 doesn't get it's IP address until much later. This works for Carlos though because he doesn't need an IP address - just the device existing. I have no idea how it worked for the stackexchange poster. Apparently because "lan0" is a virtual device as well ("sys-devices-virtual-net-lan0") that they need, not a more "physical" device like "net-devices-ens3", and it gets an IP address at the same time as creation. I've been dealing with issues like this for a while - systems with multiple interfaces, some of which do not come up for quite a while, and I need to wait for all to be up before running certain tasks. Still haven't found anything very satisfactory. -- Orion Poplawski Manager of NWRA Technical Systems 720-772-5637 NWRA, Boulder/CoRA Office FAX: 303-415-9702 3380 Mitchell Lane orion at nwra.com Boulder, CO 80301 https://www.nwra.com/