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Comment by KronisLV | Hacker News Reader

> The take-away is, secure your new stuff as early as possible, ideally even before the service is exposed to the Internet.

Honestly it feels like you'll need at least something like basicauth in front of your stuff from the first minutes it's publicly exposed. Well, either that, or run on your own CA and use self-signed certs (with mTLS) before switching over.

For example, when some software still has initial install/setup screens where you create the admin user, connect to the DB and so on, as opposed to specifying everything initially in the environment variables, config files, or other more specialized secret management solutions.

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Generally I'd recommend not exposing anything unless you deployed the security for it.

Just SSH scanning can be a big issue.

A big issue how? If you block password auth, ssh scanning is a nonissue.

Unless an attack on the sshd is employed. Which is also possible

Pre-auth sshd vulnerabilities are extremely rare and are not what ssh scanners are looking for.

DDoS attack on your sshd?

One option could be to lock the port down to only your jump/bastion server source IP.

That fails to when you lose that IP address, or you lose that server.

I suppose if you don’t have console access, sure. But inconvenient at worst imv.

If you have a way around that bastion server, then at least you've got a backup. But then you also have to worry about the security of that backup.

Yes, better to make your bastion 'dark' without being tied to an IP address. This is how we do it at my company with the open source tech we have developed - https://netfoundry.io/bastion-dark-mode/

Are we just speculating? SSH scanners are not sources of DDoS. Large companies have ssh bastions on the internet and do not worry about ssh DDoS. Its not really a thing that happens.

You don't need to freak out if you see a bunch of failed ssh auth attempts in your logs. Just turn off password based authentication and rest easy.

Agreed. Another thing you can do to drastically reduce the amount of bots hitting your sshd is to listen on a port that is not 22. In my experience, this reduces ~90% of the clutter in my logs. (Disclaimer: this may not be the case for you or anyone else)

Just to reduce the crap in the log and also because I can, I have my SSH servers (not saying what their IPs are) using a very effective measure: traffic is dropped from the entire world, except for the CIDR blocks, which I put in ipsets, of the five ISPs over three countries I could reasonably be in when I need to access the SSH servers.

And if I'm really, say, in China or Russia an really need to access one of my servers through SSH, I can use a jump host in one of the three countries that I allow.

So effectively: DROPping traffic from 98% of the planet.

Boom.

Deny by default, allow only those sources that are considered trustworthy. And frequently re-evaluate who and what should be considered trustworthy.

Or close the ports, and install an agent that phones out such as Tailscale or twingate.

Or just Wireguard itself.

This is the way, outbound only connections so you can stop all external unauthenticated attacks. I wrote a blog 2 years back comparing zero trust networking using Harry Potter analogies... what we are describing is making our resources 'invisible' to silly muggles - https://netfoundry.io/demystifying-the-magic-of-zero-trust-w...

I don't want to be able to auth whilst physically in authoritarian regimes. If I had to be physically there it'd be via burner devices.

I used to have an iptables config that just drops everything by default on the SSH port and run a DNS server that when queried a magic string would allow my IP to connect to SSH. It did help that the DNS server was actually used to manage a domain and was seeing traffic so you couldn't isolate my magic queries so easily.

Until there is a new zero day on sshd.

You want to keep these things behind multiple locked doors, not just one.

For the servers themselves, you shouldn't be able to get to sshd unless you're coming from one of the approved bastion servers.

You shouldn't be able to get to one of the approved bastion servers unless you're coming from one of the approved trusted sources, on the approved user access list, and using your short-lived sshd certificate that was signed through the use of a hardware key.

And all those approved sources should be managed by your corporate IT department, and appropriately locked down by the corporate MDM process.

And you might want to think about whether you should also be required to be on the corporate VPN. Or, to be using comparable technologies to access those approved sources.

> For the servers themselves, you shouldn't be able to get to sshd unless you're coming from one of the approved bastion servers.

What if there's a zero-day in your bastion service, whatever that is?

Until a junior from another project enables password-based root logins because Juniper team that was on site to help them install beta-version of some software they collaborated on asked them to.

Few days after they asked to redirect an entire subnet to their rack.

And yes, you still need to remember to close password logins or at least pick serious password if you need them. Helps to have no root login over SSH and normal users that aren't defaults for some distro...

It sounds like your organization has a bunch of problems. I'm sorry to hear that. But I don't think you can really blame those on ssh.

There are plenty of organizations and individuals that can competently run ssh directly on the internet (on port 22) with zero risk to "ssh scanners."

I am not blaming this on SSH (also, no longer in that org for many years).

I am just pointing out (also in few other, off-site discussions), that one should not even think of exposing a port before finishing locking it down.

Because sometimes people forget, even experienced people (including myself), and sometimes that's enough (I think someone few weeks ago submitted a story which involved getting pwned through accidentally exposed postgres?).

And there's enough people who get it wrong for various reasons that lowest of low script kiddies can profit buying ready-made extortion kits on chinese forums, getting a single VM with windows to run them, and extort money from gambling/gameserver sites. Not to mention all the fun stuff if you search for open VNC/RDP.

Your security is only as good as the people running your system. Unfortunately not everyone has teams of the best of the best. Sometimes you get a the jr dev guy assigned to things. They do not know any better and just do as they are told. It is the deputized sheriff problem.

In that case it wasn't even the junior's fault - they were following experts from Juniper who were supposed to be past-masters on installing that specific piece of crap (as someone who later accidentally became developer of that piece of crap for a time, I feel I have the basis for the claim).

And those people told him the install system didn't support SSH keys (hindsight: they did) and got him to make the root logins possible with passwords. Passwords that weren't particularly hard to guess because their only expected and planned use was for the other team to login for the first time and set their own, before the machines were to be exposed to internet, using BMC.

Yes, if you follow the advice of "not exposing anything unless you deployed the security for it" of course you block password auth before exposing SSH to the internet.

Not everyone is following that advice. Just last week I taught a friend about using tmux for long-running sessions on their lab's GPU server, and during the conversation it transpired that everyone was always sshing in using the root password. Of course plugging that hole will require everyone from the CTO downward to learn about SSH keys and start using them, so I doubt anything will change without a serious incident.

> Of course plugging that hole will require everyone from the CTO downward to learn about SSH keys and start using them

I had a similar issue 15 years ago, and tied the Linux boxes into Active Directory and authenticated via Kerberos. Worked nice, no SSH keys needed!

> something like basicauth

I wish. I use basicauth to protect all my personal servers, the problem is Safari doesn't appear to store the password! I always have to re-authenticate when I open the page. Sometimes even three seconds later.

Have you considered using a different browser?

No. Safari uses less power than any of the alternatives.

Makes sense. Is that on pc or mobile?

I use multiple browsers on my MacBook. Eg I use Google Chrome to run Google Meet, even though I don't use it otherwise.

or get your certificates using dns auth a week or so prior to exposing the service

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