Self-Hosted Main

As long as password auth is disabled you’re fine. No one is cracking your RSA key. You can add Fail2Ban to reduce the log noise, but security wise it’s fine.

Disable password auth.

Enable key only auth.

Add in TOTP 2FA (google authenticator).

Randomize the port (reduce bots) that forwards to 22.

Configure lockout to block upon 3 failed attempts, for a long duration like 1 year. (Have a backup access on LAN).

Ensure only the highest encryption ciphers are accepted.

Ensure upgrades are applied to sshd at least monthly.

If you disable password authentication, and use public key authentication, yes.

disabling password login and use pubkey authentication will be safe enough?

Just make sure you actually disable password login. Simply enabling key doesn't disable password. So as long as the password is disabled then you're fine.

Better use some kind of VPN and only open the SSH port over the VPN interface.

No. Just VPN in and SSH in.

Get fail2ban setup at a minimum

I run this on port 22 and ssh with keys on a different port

no

Should be safe enough to do this but I’ll throw in one potential caveat. Say that you one day somehow need to troubleshoot your ssh server and have to re-enable password authentication. Depending on how many other services you plan to run, it can be easy to suddenly forget you have port 22 exposed on the outside and someone could potentially break in if you use a weak password. This is why I personally host only necessary https content over port 443 to the world. I host anything else so only my wireguard vpn can access it. As for bots hitting port 22 on the outside can be another huge problem. Changing the port can disuade some but remember that the port number is only two bytes in size. A comprehensive port scan only takes a very short amount of time to complete. This, in my humble opinion, creates an extra point of access for you to remember for not that much to gain. That all being said, forwarding key protected ssh is safe enough to do.

I've opened port 22 to specific IPv4 addresses, like my employer's, friends and family.

For any other IPv4 origin, its best to set up a VPN. It's trivial to set up wireguard.

You're probably safe to open port 22 for IPv6, as the address space is unfeasibly large to be scanned, but still, the secops in me doesn't like security by obscurity, so I don't. Also, there's evidence that hackers use things like IPv6 access logs on NTP to find accessible devices to target.

Honestly? Would not recommend it. Probably no one breaking in soon, but there are just constantly tons of botnets portscanning 22 over the whole IP range. You should at least think of switching ports, but I usually recommend at least having a vpn for ssh.

SSH exposed with key auth and not password is fine. It is the exact purpose of SSH after all. Also there are milions of web servers out there with exposed SSH because a lot of their users prefer to work with SSH and CLI instead of a web UI. Big hosts such as GoDaddy, BlueHost, Hostgate and so on, all expose their SSH. You don't see their servers crash and burn every week.

Or use something like Tailscale.com, secure private mesh vpn. No need to expose any ports.

Added feature that comes with it: https://tailscale.com/tailscale-ssh/

It’s also 100% free

I keep ssh on port 80, multiplexed with usual HTTP traffic thanks to sslh. Basically it's a protocol switchboard what detects what kind of traffic reaches your server and forwards it to appropriate service. It can distinguish between SSH/HTTP/OpenVPN and a few more.

Pros? Security wise probably nothing more that SSH already offers, but port 80 is rarely (if ever) blocked on other networks and having SSH on port that is non-standard and obscured, cuts way down on random attempts to guess the user/password combination.

This is my current hardened sshd configuration.

ssh/sshd_config: https://pastebin.com/7tH36TdJ

• Public key authentication and 2fa using oathtool are used to authenticate.
• Logging in is only possible for members of the 'ssh-user' group.
• "root" login is disabled through "PermitRootLogin", "DenyGroups", and "DenyUsers".
• "restricted" has the ability to log in from any host.
• "user" is limited to using the internal network to log in.
• 'admin' can only log in when connected via WireGuard.
• "sftp" may login, but only uses the sftp server. There is no shell available.

pam.d/sshd: https://pastebin.com/eqkisf4F

• All successful pre-2FA logins will trigger the 'ssh-login-alert', which sends an NTFY alert containing the time, date, user, and host IP.
• The use of /etc/users.deny prevents root login.
• The use of /etc/users.allowed permits login by "restricted", "user", "admin" and "sftp".
• 2FA and ssh-login-alert trigger do not apply to "sftp"

Yes and no.

Yes if you have the resources to monitor and update. Companies have entire teams dedicated to this.

No if you don't have the resources/time to keep up with it regularly.

IMO, no need to take this risk when you have services like Tailscale available today.

I know that some VPN are able to create private networks for devices logged with your account. For exemple nordvpn is able to connect your devices into their "mesh network" and make your devices available through the VPN. I think it's better than exposing a ssh service on Internet, even with a lot of protections!

Is always better to randomize your ssh port, you will be safe from some scans

Most likely it's fine. Though it's not terribly difficult to set up some flavor of VPN so you're not exposing 22 at all outside your network. Personally I use Wireguard.

I recommend implementing a VPN (wireguard is working very well for me) and through that do ssh

I would not do this, people port scan all the time and thats an easy one to look for. Try using an at home vpn like openvpn or in the very least change the ssh port to something odd like 6854 or whatever.

Move it to a four digit port on your router and port for to 22 internally.

With PubKey and Fail2Ban its probably ok but wouldnt chance it personally. Can you use a different port too?

Port knocking could be useful here