this post was submitted on 04 Nov 2024
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116
Help me harden my home server (lemmy.sdf.org)
submitted 2 days ago by [email protected] to c/[email protected]
59 comments fedilink hide all child comments
 

I currently have a home server which I use a lot and has a few important things in it, so I kindly ask help making this setup safer.

I have an openWRT router on my home network with firewall active. The only open ports are 443 (for all my services) and 853 (for DoT).

I am behind NAT, but I have ipv6, so I use a domain to point to my ipv6, which is how I access my serves when I am not on lan and share stuff with friends.

On port 443 I have nginx acting as a reverse proxy to all my services, and on port 853 I have adguardhome. I use a letsencrypt certificate with this proxy.

Both nginx, adguardhome and almost all of my services are running in containers. I use rootless podman for containers. My network driver is pasta, and no container has "--net host", although the containers can access host services because they have the option "--map-guest-addr" set, so I don't know if this is any safer then "--net host".

I have two means of accessing the server via ssh, either password+2fa or ssh key, but ssh port is lan only so I believe this is fine.

My main concern is, I have a lot of personal data on this server, some things that I access only locally, such as family photos and docs (these are literally not acessible over wan and I wouldnt want them to be), and some less critical things which are indeed acessible externally, such as my calendars and tasks (using caldav and baikal), for exemple.

I run daily encrypted backups into OneDrive using restic+backrest, so if the server where to die I believe this would be fine. But I wouldnt want anyone to actually get access to that data. Although I believe more likely than not an invader would be more interested in running cryptominers or something like that.

I am not concerned about dos attacks, because I don't think I am a worthy target and even if it were to happen I can wait a few hours to turn the server back on.

I have heard a lot about wireguard - but I don't really understand how it adds security. I would basically change the ports I open. Or am I missing something?

So I was hoping we could talk about ways to improve my servers security.

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[–] [email protected] 2 points 1 day ago

They aren't going to go after your data. They will take over your machine and use it for there own purposes. This happens in a automated way and they can build botnets made of 1000's of devices.

I would strongly suggest not opening any ports. Instead use a mesh VPN like Tailscale or Netbird. You could even access it over the dark web via i2p or Tor.

[–] [email protected] 22 points 2 days ago (1 children)

Start with the basics:

  • Harden SSH by only allowing public key authentication and use strong keys to authenticate instead of passwords.
  • Setup fail2ban (lots of online resources, check Linode guides) to block malicious IPs temporarily.
  • If the data you store is something only you should see, then it should not ever be connected to the internet, airgap wherever possible.
  • And finally, keep your shit updated.
[–] [email protected] 10 points 2 days ago

To be even more explicit on the last point, that means regularly updating OpenWRT and all your containers, not just the server's base OS

[–] [email protected] 1 points 1 day ago

Unless you are a diehard FOSS person or whatever I'd recommend only using reverse tunneling and leveraging cloudflares infrastructure for access and also authentication.

It's crazy the amount of stuff they give away for free

[–] [email protected] 36 points 2 days ago (2 children)

The single best thing you can do security wise, is to NOT have any personal data on a web facing server.

Separate the data

Rereading it does look like you are doing the things right; so just audit what is on the public side. - your calendar and tasks- cool

Your photo and docs, do those need to be on there?

they are not accessible on the WAN

If they are on a server that is publicly accessible, please move them to a different location

Otherwise you sound like your doing well

[–] [email protected] 6 points 2 days ago (2 children)

That was a great answer, thank you so much!

Yes I didnt even notice the family photos and docs dont need to be on that same server. Initially I just put them there to act as a local file share. But you are absolutely right, moving them from the public server is the best thing I can do to protect them.

I will look into setting up a second server for the private stuff that is not publicluly accessible

[–] [email protected] 6 points 2 days ago (1 children)

If this server is publicly accessible and gets pwned, they can use it as a jump box for your internal devices.

[–] [email protected] 3 points 2 days ago (1 children)

Thats a good point, I hadnt thought about it before. I like the possibility of sharing these files in my intranet but I suppose you are right. Maybe I could use openwrt to split two networks, one for public stuff only, but my knowledge of networking is quite limited.

[–] [email protected] 1 points 2 days ago

Yeah what you're talking about is a DMZ, it still won't help a ton if you don't have strict firewall controls inside your network too.

I just use wireguard with firewall rules to restrict to just my server with my docker containers on it and my DNS

[–] [email protected] 2 points 2 days ago

Also, this answer.

[–] [email protected] 3 points 2 days ago (1 children)

Your photo and docs

At least in my case, it's really handy to share photos with other family members. But certainly you don't need all of them available on the same public service.

[–] [email protected] 2 points 2 days ago

Thats a good point. Maybe I can get away with just temporary file sharing. So when someone wants something I can upload it to the server and send a link. I bet even nextcloud could do that.

Still way less scary then having everything on the server all the time

[–] [email protected] 8 points 2 days ago (1 children)

Is keeping everything inside of a local “walled garden”, then exposing the minimum amount of services needed to a WireGuard VPN not sufficient?

There would be be no attack surface from WAN other than the port opened to WireGuard

[–] [email protected] 1 points 1 day ago

Minimum open services is indeed best practice but be careful about making statements that the attack surface is relegated to open inbound ports.

Even Enterprise gear gets hit every now and then with a vulnerability that's able to bypass closed port blocking from the outside. Cisco had some nasty ones where you could DDOS a firewall to the point the rules engine would let things through. It's rare but things like that do happen.

You can also have vulnerabilities with clients/services inside your network. Somebody gets someone in your family to click on something or someone slips a mickey inside one of your container updates, all of a sudden you have a rat on the inside. Hell even baby monitors are a liability these days.

I wish all the home hardware was better at zero trust. Keeping crap in isolation networks and setting up firewalls between your garden and your clients can either be prudent or overkill depending on your situation. Personally I think it's best for stuff that touches the web to only be allowed a minimum amount of network access to internal devices. Keep that Plex server isolated from your document store if you can.

[–] [email protected] 14 points 2 days ago (5 children)

Admittedly I'm paranoid, but I'd be looking to:

  1. Isolate your personal data from any web facing servers as much as possible. I break my own rule here with Immich, but I also...
  2. Use a Cloudflare tunnel instead of opening ports on your router directly. This gets your IP address out of public record.
  3. Use Cloudflare's WAF features to limit ingress to trusted countries at a minimum.
  4. If you can get your head around it, lock things down more with features like Cloudflare device authentication.
  5. Especially if you don't do step 4: Integrate Crowdsec into your Nginx setup to block probes, known bot IPs, and common attack vectors.

All of the above is free, but past step 2 can be difficult to setup. The peace of mind once it is, however, is worth it to me.

[–] [email protected] 4 points 2 days ago (1 children)

Thanks for your reply!

Suggestion 1 definetely does make a lot of sense and I will be doing exactly that asap. Its something I didnt think through before but that would make me much more in peace.

Suggestions 2-4 sound very reasonable, I have indeed searched for a way to self host a waf but didnt find much info. My only only concern with your points is... Cloudflare. From my understanding that would indeed add a lot of security to the whole setup but they would then be able to see everything going through my network, is that right?

[–] [email protected] 2 points 2 days ago (1 children)

Yes and no? It's not quite as black and white as that though. Yes, they can technically decrypt anything that's been encrypted with a cert that they've issued. But they can't see through any additional encryption layers applied to that traffic (eg. encrypted password vault blobs) or see any traffic on your LAN that's not specifically passing through the tunnel to or from the outside.

Cloudflare is a massive CDN provider, trusted to do exactly this sort of thing with the private data of equally massive companies, and they're compliant with GDPR and other such regulations. Ultimately, the likelihood that they give the slightest jot about what passes through your tunnel as an individual user is minute, but whether you're comfortable with them handling your data is something only you can decide.

There's a decent question and answer about the same thing here: https://community.cloudflare.com/t/what-data-does-cloudflare-actually-see/28660

[–] [email protected] 2 points 2 days ago

Yes absolutely. For work most of my clients use cloudflare's different services so I understand they have credibility.

For me though, part of the reason I self host is to get away from some big tech companies' grasp. But I understand I am a bit extreme at times.

So thanks for opening my mind and pointing me to that very interesting discussion, as well as for sharing your setup, it sure seems to be very sound security wise.

[–] [email protected] 1 points 2 days ago

Sounds exactly like my setup for the last 5 years, minus NGINX (don't need it with Cloidflared since each service is it's own Proxmos Container and use their own exclusive tunnels).

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[–] [email protected] 5 points 2 days ago

It's great that you self host but security especially of service directly exposed to internet is very difficult. Use somekind of Direct VPN or services like tailscale etc

[–] [email protected] 5 points 2 days ago

Why don't you use something like Tailscale? Other than that using non standard ports greatly reduces the risks of you getting compromised. The majority of attacks come from port scanners scanning for default ports and trying to use known vulnerabilities.

[–] [email protected] 12 points 2 days ago (1 children)

Wireguard is a VPN, so that's not going to help you much here unless you're forwarding all your traffic through a remote server, in which case anyone gets in there will still be able to get your local machines. It's another hop in the chain, but that's about it.

If you want to be more on guard about reacting to attacks, or just bad traffic, you probably want something like Crowdsec. You'll at least be able to detect and ban IPs probing your services. If that's too much work, leverage OoenWRT reporting and some scripting to ban bad actors that probe your firewall and open ports. That's a good first step.

If you're concerned about the containers, consider using something more secure than dockerd. Podman rootless with a dedicated service user is a good start. Then maybe look at something more complex: Kata, gvisor, lxc...etc. The goal being sandboxing the containers more to prevent jailbreaks.

[–] [email protected] 4 points 2 days ago (1 children)

Thanks for the amazing reply and specially for the explanation regarding wireguard.

I didnt know about crowsec and kata containers, both amazing projects, I will definetely look into it and try to set them up.

Just one quick follow up question, when you mention dedicanted service user, do you mean its best to have a sepate user for each service, such as one for nginx, one for adguardhome and so on? Currently all of them run under the same user and I didnt think about this possibility before.

[–] [email protected] 4 points 2 days ago (1 children)

Yeah, so if you're running rootless containers, they aren't run by root, and for added security, you don't want them run by your normal user because if they get broken, then they'd have access to what your user has access to. Just create another user that only runs containers, and doesn't have access to your things or root.

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[–] [email protected] 6 points 2 days ago (3 children)

does anyone have an actual horror story about anything happening via an exposed web service? let's set aside SSH

[–] [email protected] 11 points 2 days ago* (last edited 2 days ago)

Counter question

How would you know something went wrong? Do you monitor all the logs? Do you have alerting?

What happens if one service has a serious vulnerability and is compromised? Would an adversary be able to do lateral movement? For that matter are you scanning/checking for vulnerabilities? Do you monitor security tracker?

All of these are things to consider

[–] [email protected] 5 points 2 days ago (2 children)

Yeah, a company got toasted because one of their admins was running Plex and had tautulli installed and opened to the outside figuring it was read-only and safe.

Zero day bug in tat exposed his Plex token. They then used another vulnerability in Plex to remote code execute. He was self-hosting a GitHub copy of all the company's code.

[–] [email protected] 2 points 2 days ago

This guy was running a three year old version of Plex with a known (and later fixed RCE), and was working for LastPass.

[–] [email protected] 1 points 2 days ago

Last time they’ll ever do that! Pass the buck of hosting web-facing Plex servers onto somebody else.

[–] [email protected] 3 points 2 days ago (1 children)

Id like to know as well. I definetely dont want to be the first person of that story tough

Ive heard of someone who exposed the docker management port on the internet and woke up to malware running on their server. But thats of course not the same as web services.

[–] [email protected] 3 points 2 days ago

Once a server is compromised there are lots of uses. Everything from DDOS attacks to obscuring attacks against other targets. An attacker doesn't want to be discovered so they likely will hide as much as they can.

[–] [email protected] 6 points 2 days ago (3 children)

Something you might want to look into is using mTLS, or client certificate authentication, on any external facing services that aren't intended for anybody but yourself or close friends/family. Basically, it means nobody can even connect to your server without having a certificate that was pre-generated by you. On the server end, you just create the certificate, and on the client end, you install it to the device and select it when asked.

The viability of this depends on what applications you use, as support for it must be implemented by its developers. For anything only accessed via web browser, it's perfect. All web browsers (except Firefox on mobile...) can handle mTLS certs. Lots of Android apps also support it. I use it for Nextcloud on Android (so Files, Tasks, Notes, Photos, RSS, and DAVx5 apps all work) and support works across the board there. It also works for Home Assistant and Gotify apps. It looks like Immich does indeed support it too. In my configuration, I only require it on external connections by having 443 on the router be forwarded to 444 on the server, so I can apply different settings easily without having to do any filtering.

As far as security and privacy goes, mTLS is virtually impenetrable so long as you protect the certificate and configure the proxy correctly, and similar in concept to using Wireguard. Nearly everything I publicly expose is protected via mTLS, with very rare exceptions like Navidrome due to lack of support in subsonic clients, and a couple other things that I actually want to be universally reachable.

[–] [email protected] 2 points 2 days ago

mTLS is great and it's a shame Firefox mobile still doesn't support it.

[–] [email protected] 1 points 2 days ago

Sounds like the clearnet equivalent to i2p encrypted lease sets

[–] [email protected] 1 points 2 days ago

Wow, thats very, very nice. I didnt know this even existed.

But I suppose if it had widespread support it would be the perfect solution.

Firefox mobile not supporting it might be a dealbreaker though, since it is the browser I use and the one I persuaded all my friends and family to switch to...

But this is an incredibly interesting technology and I will surely look into implementing at least partially if that works.

Thanks a lot for sharing!

[–] [email protected] 6 points 2 days ago (2 children)

Just do what I do and consistently forget to set up DDNS and also be bad at noticing when your ISP juggles your IP address.

[–] [email protected] 6 points 2 days ago (2 children)

Been there, done that lol, my ISP doesnt change my IP half as much as I should like, and I renew my certs half as often as they deserve.

Seriously though, I had certs expire twice until I finally decided to get this setup properly.

[–] [email protected] 1 points 2 days ago

Why would you like your IP to change? My ISP never changed mine and I thank them for that

[–] [email protected] 2 points 2 days ago

It makes sense that Bilbo would run a homeserver.

[–] [email protected] 2 points 2 days ago

Get a VPS and route traffic into a isolated network

[–] [email protected] 2 points 2 days ago (4 children)

Just close 443 and use VPN with ACME DNS challenges for your certs. That'll help make it even more secure, nothing is full proof though and a VPN is a good first step

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