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Do I Need to Harden SSH over Tor? (infosec.pub)
submitted 2 years ago by anon2963@infosec.pub to c/selfhosted@lemmy.world
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cross-posted from: https://infosec.pub/post/10908807

TLDR:

If I use SSH as a Tor hidden service and do not share the public hostname of that service, do I need any more hardening?

Full Post:

I am planning to setup a clearnet service on a server where my normal "in bound" management will be over SSH tunneled through Wireguard. I also want "out of bound" management in case the incoming ports I am using get blocked and I cannot access my Wireguard tunnel. This is selfhosted on a home network.

I was thinking that I could have an SSH bastion host as a virtual machine, which will expose SSH as a a hidden service. I would SSH into this VM over Tor and then proxy SSH into the host OS from there. As I would only be using this rarely as a backup connection, I do not care about speed or convenience of connecting to it, only that it is always available and secure. Also, I would treat the public hostname like any other secret, as only I need access to it.

Other than setting up secure configs for SSH and Tor themselves, is it worth doing other hardening like running Wireguard over Tor? I know that extra layers of security can't hurt, but I want this backup connection to be as reliable as possible so I want to avoid unneeded complexity.

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[-] Acters@lemmy.world 3 points 2 years ago* (last edited 2 years ago)

Yes, but I usually add my public key to the authorized_keys file and turn off password authentication once i do login with a password. On top of that, I have a sshpass one line command that takes care of this for me. It's much easier than trying to manually type a password for the next time. I save it and just run it every time I think about using password login. Next time I need to ssh, I know the password login is not necessary.

sshpass -p 'PASSWORD' ssh USER@IP.ADDRESS "echo '`cat ~/.ssh/id_rsa.pub`' > ~/.ssh/authorized_keys && echo 'Match User !root
PasswordAuthentication no
Match all' > /etc/ssh/sshd_config' && exit" && ssh USER@IP.ADDRESS

At the next reboot, your system will now only accept key logins, except for root. I hope the root user password is secure. I don't require it for root because if a hacker does gain shell access, a password(or priv esc exploit) is all they need to gain root shell. It is also a safety net in case you need to login and lost your private key.

this post was submitted on 10 Apr 2024
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