So it’s my first time setting up a VPS. Is it to be expected to ban 54 IPs over a 12h timespan? The real question for me is whether this is normal or too much.

$ sudo fail2ban-client status sshd
Status for the jail: sshd
|- Filter
|  |- Currently failed: 3
|  |- Total failed:     586
|  `- Journal matches:  _SYSTEMD_UNIT=ssh.service + _COMM=sshd
`- Actions
   |- Currently banned: 51
   |- Total banned:     54
   `- Banned IP list:   [list of IPs]

fail2ban sshd.conf

$ sudo cat /etc/fail2ban/jail.d/sshd.conf 
[sshd]
enabled = true
mode = aggressive
port = ssh
backend = systemd
maxretry = 3
findtime = 600
bantime = 86400

I have disabled SSH login via password. And only allow it over an SSH key.

$ sudo sshd -T | grep -E -i 'ChallengeResponseAuthentication|PasswordAuthentication|UsePAM|PermitRootLogin'
usepam no
permitrootlogin no
passwordauthentication no
  • pHr34kY@lemmy.worldEnglish
    142·
    2 days ago

    They’re portscanning bots.

    I made SSH IPv6-only and it stopped. You can’t scan IPv6 space for open ports.

        • pHr34kY@lemmy.worldEnglish
          141·
          1 day ago

          The smallest possible subnet has 18.4 quintillion addresses.

          You can’t scan it before encountering the heat death of the universe.

          Outgoing connections are made on a different address that does not accept incoming connections. You never disclose your real IP when browsing.

          So, no. It can’t be done.

          • Possibly linux@lemmy.zipEnglish
            4·
            15 hours ago

            That’s only if you use the brute force method

            IPs are not secret and can be leaked in various ways. Don’t count on IPv6 as a security mechanism as that’s not what it was designed to do

            • pHr34kY@lemmy.worldEnglish
              12·
              14 hours ago

              It’s literally called “IPv6 privacy extension”. It’s what it does.

              Unless you’re in the middle and fowarding the packets, you won’t stumble across a connectable IPv6 endpoint.

              • Possibly linux@lemmy.zipEnglish
                4·
                13 hours ago

                The IPv6 privacy extensions are something else entirely and are not used for anything server side

                You should research IPv6 port scanning techniques. It is harder than IPv4 but still doable depending on the context. If your goal is simply to reduce network traffic due to bots that’s one thing. However, it should not be considered a security mechanism.