Comment on Using systemd-networkd vs ifupdown on Debian

TCB13@lemmy.world ⁨1⁩ ⁨year⁩ ago

• dr_robot@kbin.social ⁨1⁩ ⁨year⁩ ago

  Thanks for your reply! One thing I'm struggling with networkd is hysteresis. That is, toggling the interface down and then back up does not do what I expect it to. That is, setting the interface down does not clear up the configuration, and setting the interface up does not reconfigure the interface. I have to run reconfigure for that. I was hoping that the declarative approach of networkd would make it easy to predict interface state and configuration.

  This does make sense because configuration is not the same as operational state. However, what would the equivalent of ifdown (set interface down and remove configuration) and ifup (set interface up and reconfigure) be using networkd and networkctl? This kind of feature would be useful for me to test config changes, debug networking issues, disconnect part of the network while I'm making some changes, etc.

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  • TCB13@lemmy.world ⁨1⁩ ⁨year⁩ ago

    I get your points and that’s a valid issue however, systemd-networkd is designed for more persistent configurations but you’ve a few options:

    1. systemctl reload systemd-networkd and networkctl reload. Don’t forget that if you change units on the filesystem a systemctl daemon-reload is required before the previous commands.

    2. networkctl commands such as reload, reconfigure, up, down and renew. Read more about them here.

    3. Temporary / volatile runtime units: manually drop a config under /run/systemd/network/ it will apply until you reboot the machine.

    4. Transient scope units: those are kind of supersede temporary units as they are managed through a D-Bus interface so 3rd party interface can manage systemd. They don’t seem to work right now for network, but they might eventually do and this allows you to change options dynamically like they do for standard services.

    An interesting thing to consider is that in most cases you can have your network configurations in /etc/systemd/network but only bring them online when required. This for me seems to solve most cases, you’ve your network all configured and ready to go.

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    • dr_robot@kbin.social ⁨1⁩ ⁨year⁩ ago

      Thanks for this useful reply! I think I'll just need to closely examine my setup and figure out if I really need the ability to up/down interfaces like I described or whether the more persistent approach of networkd is actually more suitable for me. Sometimes I just want to reproduce behaviour that I've used before, but may not actually need.

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      • TCB13@lemmy.world ⁨1⁩ ⁨year⁩ ago

        Well networkctl up enXX + pre-configured network files with the addresses and whatnot might be a suitable replacement for your requirements.

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