Another good reason not to open port 22

In the past two weeks I set up a new VPS, and I run a small experiment. I share the results for those who are curious.

Consider that this is a backup server only, meaning that there is no outgoing traffic unless a backup is actually to be recovered, or as we will see, because of sshd.

I initially left the standard “port 22 open to the world” for 4-5 days, I then moved sshd to a different port (still open to the whole world), and finally I closed everything and turned on tailscale. You find a visualization of the resulting egress traffic in the image. Different colors are different areas of the world. Ignore the orange spikes which were my own ssh connections to set up stuff.

Main points:

  • there were about 10 Mb of egress per day due just to sshd answering to scanners. Not to mention the cluttering of access logs.
  • moving to a non standard port is reasonably sufficient to avoid traffic and log cluttering even without IP restrictions
  • Tailscale causes a bit of traffic, negligible of course, but continuous.
Clou42,

I’ll take that tiny amount of traffic telling scanners there’s no password auth over having to remember port settings for ssh, scp and rsync any day.

lando55,

For me it’s not about the traffic, more the log spam.

Generally I’ll have :22 enabled internally, and anything non-standard is defined in ~/.ssh/config and shared out so I don’t have to remember things.

dmrzl,

My configs remember stuff for me.

gamer,

vim ~/.ssh/config

ndsvw, (edited )

Yeah, but how do you close VIM then? Restarting the computer takes some time!!!111

Checkmate!!

maiskanzler,

Fair point. These logs are only useless chatter anyway for everyone with proper key auth.

marketingpro123,

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ptman,

Prevent password auth and setup sshguard. Wireguard is very nice in that it doesn’t support password auth.

MoshpitDaddy,

I don’t know if it was mentioned already but how could I check if my ports are under “attack”? OPs graphic looks really nice

aesir,

Hi, to check attacks you should look at the logs. In this case auth.log. Being attacked on port 22 is not surprising neither really troublesome if you connect via key pair.

My graph was showing egress traffic, on any kind of server the traffic due to these attacks would have been invisible but on a backup server which has (hopefully) only ingress you can clearly see the volume of connections from attackers from bytes teansmitted

ShortN0te,

And yet it is more likely that tailscale get owned since the reward is much higher. I take my chances with my secured openssh server at port 22 vs a 3rd party company who controlls the access.

Rearsays,

Just setup a wireguard system that’s pretty bulletproof

ShortN0te,

So is SSH

Rearsays,

Wireguard doesn’t respond but I agree open-ssh is pretty solid. Can’t speak for any of the other ssh implementations. It can also be poorly configured. Like you could use a password

droans,

The benefit of Wireguard is that if you screw it up, it just won’t work. It basically enforces security.

Well, unless you tried to use the original PFSense module.

wgs,
@wgs@lemmy.sdf.org avatar

I get what you say, and you’re definitely not wrong to do it. But as I see it, you only saved ~80Kib of ingress and a few lines of logs in the end. From my monitoring I get ~5000 failed auth per day, which account for less than 1Mbps average bandwidth for the day.

It’s not like it’s consuming my 1Gbps bandwidth or threatening me as I enforce ssh key login. I like to keep things simple, and ssh on port 22 over internet makes it easy to access my boxes from anywhere.

aesir,

ssh -p 12345 would leave your boxes accessible from anywhere too. Other blocks of IPs receive 10 times or more requests, as scanners can focus on blocks of ips from major providers.

wgs,
@wgs@lemmy.sdf.org avatar

Yeah I know, I just don’t really care about that traffic to bother changing it :) Also, I’m talking about a server hosted on Hetzner, so I feel like it’s scanned a lot.

oatscoop,

I don’t get why people leave interfaces the public doesn’t need access to open to the public – especially SSH.

Use a VPN if you need access to those interfaces from the “outside”. They’re stupidly easy to set up these days, particularly with Wireguard.

wgs,
@wgs@lemmy.sdf.org avatar

A VPN is easy to setup (and I have it setup by the way), but no VPN is even easier. SSH by itself is sufficiently secure if you keep it up to date with a sane configuration. Bots poking at my ssh port is not something that bother me at all, and not part of any attack vector I want to be secure against.

Out of all the services I expose to the clear web, SSH is probably the one I trust the most.

oatscoop,

Defense in depth – maybe I’m paranoid, but just because something is unlikely doesn’t mean an extra layer of security isn’t advantageous. Particularly when I already have a VPN, so there’s little reason not to use it.

Plus, my logs are easily checked as a side effect.

wgs,
@wgs@lemmy.sdf.org avatar

To each their own ! Security is a complex topic which usually resolves to adjusting the “security/annoyance” cursor to the best position.

In my case the constraints of using a VPN simply outweighs the security benefits.

sturmblast,

I would generally agree with this a strong password and SSH without keys has never gone sideways for me and over 15 years of having public Linux servers. but I also make sure to install all security updates on a regular basis on any server no matter what SSH configuration is.

wgs,
@wgs@lemmy.sdf.org avatar

Agreed ! Also it would make graphs pretty boring ;)

https://lemmy.sdf.org/pictrs/image/ab79c390-ea9c-4ce6-a21b-c0b429275f3f.png

MonkderZweite,

I don’t get tailscale? In-kernel Wireguard is easy to setup. What does it add to this?

mplewis,

Tailscale is a nice way to set up a private network between your machines. It’s perfectly fine.

BinAmProkrastinieren,

deleted_by_author

    •
    mplewis,

    Networking two machines is easy; networking several with good onboarding and DNS is not as easy.

    drathvedro,

    Tailscale is built on top of wireguard. It just manages all the hassle of configuring it. In my case it was a godsend as I have like 10 devices all roaming and scattered across multiple countries. It’d be a massive headache to type down IPs and whatnot every time one changes networks.

    stown,

    I believe it adds a third party server to help facilitate communication between clients.

    Justice,
    @Justice@lemmygrad.ml avatar

    I think it’s just the ease of GUI for people. This isn’t to shit on anyone, btw. A lot of people don’t like dealing with the keys and IPs involved, few as there may be, with setting up wireguard.

    If someone else has a compelling difference or reason to use tailscale then I’d be happy to hear it. I tried it once and it worked fine enough. But wireguard works just as fine and takes the same time to setup if you already know what to do. Like wireguard seriously takes 2 minutes.

    sasoiliev,

    I’m not using Tailscale, but I’d imagine that if you wanted to form a private network that involves devices controlled by non-technical people, the GUI becomes less of a “don’t like to deal with keys/IPs” and more of a “can’t deal”.

    MonkderZweite,

    Didn’t see it has GUI. Valid argument, thanks.

    yoz,

    I am not in IT, what does this mean ?

    elscallr,
    @elscallr@lemmy.world avatar

    Computers communicate across networks using ports. Port 22 is a commonly used remote administration port called ssh. Bots go around probing computers with an open port 22 hoping to find badly secured or outside misconfigured ssh servers to turn them into bots and crypto miners, etc.

    yoz, (edited )

    Its crazy people can do all these stuff. I can’t even edit my word document. Being said that I want to learn IT but looks hell stressful for $100-$200k job. I was in content & marketing making $130k and we used to discuss about shades of color to use in a font for 3-4 weeks. Its crazy how you guys have to fix issues within minutes on those tickets. The more i learn about IT, I feel like I should stay away from it.

    xeddyx,

    Not everyone in IT needs to fix tickets or work in a high-stress environment. In one of my previous roles, I was a projects engineer, and I was basically given a bunch of projects to work on (like there was a small python-based project - they needed to automate something; then there was one to get them into a hybrid cloud setup; another project to upgrade something and so on). I didn’t really have any break-fix tickets to work on, although I was occasionally asked if I could help, when there was some spare time or if it was something high-level the ops guys couldn’t fix. Basically a total chill job, I was free to allocate time on my projects as I saw fit, no hard deadlines, no SLAs to meet, and the best part - no users to deal with.

    Of course, it wasn’t always like this. To get here, I had to do those grunt roles first, those stressful jobs with tickets that needed to be fixed in minutes, dealing with angry users and stuff. But thankfully my career has progressed past that stage now.

    elscallr,
    @elscallr@lemmy.world avatar

    I can’t edit Word documents for shit lol. I edit everything using Markdown (the same formatting used here) because I don’t have to think about it.

    That said every job can get stressful now and again, and this line of work is no different, but most days it’s just work. Make this change, make this thing do something else, kill this thing that’s costing money and everyone stopped using last year without telling anyone, etc. Typical things.

    Saigonauticon,

    One of the sad aspects of my job (in IT) is building tools to eliminate less stressful jobs, especially ones that pay well (usually management or accounting, in my case). Design has definitely been a specific target in recent years though – off the top of my head I could at least imagine two approaches to writing a tool that automates color and font selection with results comparable to human expertise.

    This is one reason it’s a good idea to regularly study new things (IT or otherwise). I have to retool every few years as whatever I know becomes obsolete – this used to mainly be a frustration in IT, but is rapidly becoming a necessary process in other fields. It won’t be necessary to become an IT expert, but I would keep up-to-date on how to use the new tools technology provides… especially if I wanted to keep a job in say, graphics design or copywriting!

    (Incidentally, my first job in this country was in marketing! It was high-stress and I did not earn 130k. I recall font and color choice processes vividly :D)

    yoz,

    Yea dont create anything bro. 100k-200k is nothing in 2023. Like you can’t even afford a decent house for a family. I do my 9-5 with the least work possible and go home. Tried starting a business but failed miserably so back to 9-5.

    Saigonauticon,

    Yeah… I couldn’t cope with that unfortunately (I’m a bit jealous, it sounds nice). I need to work long hours and make things, it’s a compulsion. “Taking it easy” can stress me out to the point where I end up in a hospital.

    So I sold all my worldly possessions and immigrated to the developing world on an investment visa (where things are made). My timing was a few years early, but I had no path to a decent life left except having my own company in a growth economy – my entire industry vanished twice overnight in my home country due to changes in legislation.

    Nowadays, looking at the local economy, there is no path to home ownership except for people who own companies, and maybe senior executives or senior software engineers. An average university-educated couple would have to save 100% of their income for their entire adult life to afford a nice home – if they don’t have kids. I think this kind of cruel equation is slowly coming to the West too – although you guys have more land so I guess it takes longer.

    yoz,

    Feel for you brother. Dont get dominated by stupid 9-5 managers, directors, CEO instead try dominating them. They cant do all thr work by themselves , even if they fire you, its a 9-5 job. You have to take what’s yours legally or illegally. Look at the history from colonization to new era Capitalism. More power to you bro!

    Saigonauticon,

    Perhaps ironically, I live in a nominally Communist country that went through decolonization quite a number of times. It doesn’t change much in my daily life (I’m not really political), although I arguably own some tiny slice of the means of production these days. So maybe in retirement I’ll provide public access to those for working class people. That would be really fun, I think. Who knows what we might create together? Certainly if the machines are sitting unused in my retirement, they are creating nothing, and I would feel sad for the machines.

    I don’t do the whole 9-5 thing. That would stress me out! I work as long as I feel like, any day of the week I feel like. Generally, this is really nice for both managing stress (there’s always tomorrow!) and steamrolling over any competition.

    I’m just a mercenary (and a bureaucrat) though. You pay my fee in filthy lucre, and the job gets done – legally, and reliably. If someone annoys me with politics at a client, I just try and replace them with a computer program. The result is that several of my best coworkers are machines these days. I foresee that trend increasing with time.

    solberg,

    Is public key authentication not good enough? Tailscale is cool but can be tedious if you also use other VPNs

    bjornp_,

    Yeah that’s what I have too. One of my servers is exposed with key auth and I just tunnel to other servers from there. A few MB egress is nothing compared with the amount of spam my webserver needs to deal with

    axum,
    axum avatar

    ITT: People who don't understand Tailscale or are allergic to it for 'reasons'

    PhilBro,

    Throw CrowdSec on there to stop the bots before they can do anything

    FrederikNJS,

    As others have already said, set up a VPN like wireguard, connect to the VPN and then SSH to the server. No need to open ports for SSH.

    I do have port 22 open on my network, but it’s forwarded to an SSH tarpit: github.com/skeeto/endlessh

    VitoCorleone,

    I have wireguard for other purposes but I also have ssh open on a different port. I don’t much understand the argument of exchanging ssh for wireguard. In the end, we’re just trading an attack vector for another.

    My ssh only allows connections from my user. If I’m using password auth, I also request a 2FA.

    Tail scale is also a good idea but I don’t like having my control plane under someone else’s control.

    barsoap,

    If someone finds a 0day in your SSH server and goes on drive-by attacking the whole internet you’re toast.

    Already moving off port 22 reduces much of the risk, essentially reducing the attack surface for drive-by attacks to zero while still being susceptible to targeted attacks – that is, still susceptible to attackers bothering to scan the whole range. Anything that makes you unscannable (VPN, portknockd, doesn’t matter) mitigates that. Even state-level actors would have to be quite determined to get through that one.

    Yes it’s security through obscurity. Yes it’s a good idea: There’s a difference between hiding your unlocked front door and hiding your military-grade front door lock, one of them is silly the other isn’t.

    axum,
    axum avatar

    So just run headscale then.

    Cyberflunk,

    Or nebula

    FrederikNJS,

    The reason a VPN is better to expose than SSH, is the feedback.

    If someone tries connecting to your SSH with the wrong key or password, they get a nice and clear permission denied. They now know that you have SSH, and which version. Which might allow them to find a vulnerability.

    If someone connects to your wireguard with the wrong key, they get zero response. Exactly as if the port had not been open in the first place. They have no additional information, and they don’t even know that the port was even open.

    Try running your public IP through shodan.io, and see what ports and services are discovered.

    486,
    486 avatar

    There is quite a significant difference. An ssh server - even when running on a non-default port - is easily detectable by scanning for it. With a properly configured Wireguard setup this is not the case. As someone scanning from the outside, it is impossible to tell if there is Wireguard listening or not, since it simply won't send any reply to you if you don't have the correct key. Since it uses UDP it isn't even possible to tell if there is any service running on a given UDP port.

    filister,

    But Tailscale is Wireguard under the hood.

    Holzkohlen,

    Yeah, but worse cause it’s company owned and not really open source. Why do people use tailscale? Are you so desperate to pay money for it?

    art,
    @art@lemmy.world avatar

    It’s open source and it’s free to use. Anything can sound bad when you just make shit up.

    greavous,

    I don’t pay money for it… 3 users/100 devices is free tailscale.com/pricing/

    James,

    Public key auth, and fail2ban on an extremely strict mode with scaling bantime works well enough for me to leave 22 open.

    Fail2ban will ban people for even checking if the port is open.

    timi,

    Honest question, is there a good default config available somewhere or is what apt install fail2ban does good to go? All the tutorials I’ve found have left it to the reader to configure their own rules.

    Sleepkever,

    Honestly the default config is good enough to prevent brute force attacks on ssh. Just installing it and forgetting about it is a definite option.

    I think the default block time is 10 minutes after 5 failed login attempts in 10 minutes. Not enough to ever be in your way but enough to fustrate any automated attacks. And it’s got default config for a ton of services by default. Check your /etc/fail2ban/jail.conf for an overview.

    I see that a recidive filter that bans repeat offenders for a week after 10 fail2ban bans in one day is also default now. So I’d say that the results are perfect unless you have some exotic or own service you need fail2ban for.

    bitsplease,

    Yeah fail2ban has worked great for me

    JubilantJaguar,

    If Fail2Ban is so important, why the h*** does it not come installed and enabled as standard?!

    Security is the number-1 priority for any OS, and yet stock SSHD apparently does not have Fail2Ban-level security built in. My conclusion is that Fail2Ban cannot therefore be that vital.

    Feathercrown,

    I opened a raw text channel on the Telnet port for a personal game engine project and someone tried to enable commands and do some shady stuff. Unfortunately for them, that’s not a valid chess move.

    notabot,

    You really shouldn’t have something kike SSHD open to the world, that’s just an unnecessary atrack surface. Instead, run a VPN on the server (or even one for a network if you have several servers on one subnet), connect to that then ssh to your server. The advantage is that a well setup VPN simply won’t respond to an invalid connection, and to an attacker, looks just like the firewall dropping the packet. Wireguard is good for this, and easy to configure. OpenVPN is pretty solid too.

    JDubbleu,

    I usually just run a ZeroTier client on my Pi connected to a private P2P network to solve this issue, and then have ProtonVPN over Wireguard for all internet traffic in and out of the Pi.

    douglasg14b,
    @douglasg14b@lemmy.world avatar

    You say this and are downvoted.

    While we are coming off the tail of Def Con where there where a plethora or small talks and live examples of taking advantage and abusing just this.

    u202307011927,

    I don’t understand your comment, what you are saying. Could you elaborate a bit, please? I’m interested why it’s a bad idea what previous comment suggested.

    Of course I can dig into DefCon videos and probably would do if needed, but perhaps you know what exactly the issue is

    MaggiWuerze,

    The first this means the comment he answered to and the second one means ssh being used as an attack surface, being described in defCon talks

    teawrecks,

    Just trying to parse your comment, I assume your first “this” and second “this” are referring to different things, right?

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