Comment on How to Setup a Secure Ubuntu Home Server: A Complete Guide

• martinb@lemmy.sdf.org ⁨1⁩ ⁨day⁩ ago

  Passwordless login only. No root login. Fail2ban. Add ufw to stop accidental open port shenanigans, and you are locked down enough

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  • Botzo@lemmy.world ⁨1⁩ ⁨day⁩ ago

    We can go harder: port knock to open the port to a cert-only VPN:

    wiki.archlinux.org/title/Port_knocking

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    • martinb@lemmy.sdf.org ⁨1⁩ ⁨day⁩ ago

      Felt a bit like a faff to me, so I never bothered. Does depend upon your threat model though

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      • Botzo@lemmy.world ⁨1⁩ ⁨day⁩ ago

        Totally.

        Port knocking is one of those “of course someone did that” things to me too. A replay attack is enough to make it security theater.

        An IP allowlist is a more useful addon.

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  • StrixUralensis@tarte.nuage-libre.fr ⁨1⁩ ⁨day⁩ ago

    Passwordless login only

    Never understood this

    I don't think that anyone or anyrhing, computer or mentalist, will guess my 40+ characters long password

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    • non_burglar@lemmy.world ⁨1⁩ ⁨day⁩ ago

      With ssh, over 90% of the vulnerabilities are abusing the password mechanism. If you setup pre-shared keys, you are preventing the most common abuses, including in the realm of zero days.

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      • StrixUralensis@tarte.nuage-libre.fr ⁨1⁩ ⁨day⁩ ago

        Oh I see, ty !

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    • etchinghillside@reddthat.com ⁨1⁩ ⁨day⁩ ago

      Are you setting and managing other’s passwords?

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    • surph_ninja@lemmy.world ⁨1⁩ ⁨day⁩ ago

      Especially paired with Fail2Ban preventing any brute force attempts.

      But with a WireGuard setup, you need not have the port exposed at all.

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    • truthfultemporarily@feddit.org ⁨1⁩ ⁨day⁩ ago

      The idea behind keys is always, that keys can be rotated. Vast majority of websites to that, you send the password once, then you get a rotating token for auth.

      Most people don’t do that, but you can sign ssh keys with pki and use that as auth.

      Cryptographically speaking, getting your PW onto a system means you have to copy the hash over. Hashing is not encryption. With keys, you are copying over the public key, which is not secret. Especially managing many SSH keys, you can just store them in a repo no problem, really shouldn’t do that with password hashes.

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• emhl@feddit.org ⁨1⁩ ⁨day⁩ ago

  Privileged ports can be used by processes that are running without root permissions. So if the sshd process would crash or stop for some other reason, any malicious user process could pretend to be the real ssh server without privilege escalation. To be fair this isn’t really a concern for single user systems. But setting up fail2ban or only making ssh accessible from a local network or VPN would probably be a more helpful hardenening step

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  • Laser@feddit.org ⁨1⁩ ⁨day⁩ ago

    Privileged ports can be used by processes that are running without root permissions.

    I guess you mean unprivileged ports?

    So if the sshd process would crash or stop for some other reason, any malicious user process could pretend to be the real ssh server without privilege escalation.

    Not really, except on the very first connection because you need access to the root-owned and otherwise inaccessible SSH host key, otherwise you’ll get the message a lot of people have probably seen after they reinstalled a system (something like “SOMEONE MIGHT BE DOING SOMETHING VERY NASTY!”).

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