42
Do I Need to Harden SSH over Tor? (infosec.pub)
submitted 2 years ago by anon2963@infosec.pub to c/selfhosted@lemmy.world
26 comments fedilink hide all child comments

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.

you are viewing a single comment's thread
view the rest of the comments
[-] Audalin@lemmy.world 8 points 2 years ago

Disabling root login and password auth, using a non-standard port and updating regularly works for me for this exact use case.

[-] tal@lemmy.today 9 points 2 years ago* (last edited 2 years ago)

using a non-standard port

It's really not that hard to find SSH servers running on a non-standard port.

nmap or a similar port-scanning software package can find ports listening for TCP connections. There are software packages -- don't recall names off-the-cuff, but I'm sure that you could go dig one up -- that connect to ports and then aim to identify the protocol from a fingerprint out of a database that they have. The SSH protocol has a very readily-identifiable fingerprint, don't even need specialized software.

Let me just bounce to a machine as an example:

$ telnet tals-host.tals-domain.com 22
Trying tals-IP...
Connected to tals-host.tals-domain.com
Escape character is '^]'.
SSH-2.0-OpenSSH_9.6p1 Debian-4
^]
telnet> q
Connection closed.
$

That being said, I don't disagree with your broader point that I wouldn't personally bother with trying to add more layers on top of ssh, as long as you're keeping current on updates.

[-] Getting6409@lemm.ee 11 points 2 years ago

I feel like the argument for using a nonstandard ssh port these days is that you dodge the low tier automation/bots that are endlessly scanning IPs and port 22 and trying obvious usernames and passwords. I do also question how much it is worth dodging these since presumably you'd have already done the other basics like key only and no root login before this. Maybe there's some value if you want a clean auth.log or equivalent

this post was submitted on 10 Apr 2024
42 points (93.8% liked)

Selfhosted

62841 readers
909 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

Detailed Rules Post

  1. Be civil.

  2. No spam.

  3. Posts are to be related to self-hosting.

  4. Don't duplicate the full text of your blog or readme if you're providing a link.

  5. Submission headline should match the article title.

  6. No trolling.

  7. Promotion posts require active participation, with an account that is at least 30 days old. F/LOSS without a paywall has exceptions, with requirements. See the rules link for details. Tags [CBH] or [AIP] are required, see the links in Rule 8 for details.

  8. AI-related discussions and AI-involved promotional posts have additional requirements for tagging, as noted in Rule 7 and the AI & Promotional Post Expanded Rules post, and find example disclosures here.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 3 years ago
MODERATORS
ruud@lemmy.world
Loki@lemmy.world
CannaVet@lemmy.world
devve@lemmy.world
ayyy@sh.itjust.works
curbstickle@anarchist.nexus
curbstickle_lw@lemmy.world