Bit of a followup to my previous post. I now have a VPS with nginx working as a reverse proxy to some services on my DMZ. My router (UDM pro) is running a wireguard server and the VPS is acting as a client.

I’ve used Letsencrypt to get certs for the proxy, but the traffic between the proxy and the backend is plain HTTP still. Do I need to worry about securing that traffic considering its behind a VPN? If I should secure it, is there an easier way to do self-signed certs besides spinning up your own certificate authority? Do self-signed certs work between a proxy and a backend, or would one or the other of them throw a fit like a browser does upon encountering a self-signed cert?

I’d rather not have to manage another set of certs just for one service, and I don’t want to involve my internal domain if possible.

  • NaibofTabr@infosec.pubEnglish
    5·
    10 hours ago

    You can just use openssl to generate x509 certificates locally. If you only need to do this for a few local connections, the simplest thing to do is create them manually and then manually place them in the certificate stores for the services that need them. You might get warnings about self-signed certificates/unrecognized CA, but obviously you know why that’s the case.

    This method becomes a problem when:

    1. You need to scale - manually transferring certs is fine maybe half a dozen times, after that it gets real tedious and you start to lose track of where they are and why.
    2. You need other people to access your encrypted services - self-signed certs won’t work for public access to an HTTPS website because every visitor will get a warning that you’re signing your own encryption certs, and most will avoid it. For friends and family you might be able to convince them that your personal cert is safe, but you’ll have to have that conversation every time.
    3. You need to implement expiration - the purpose of cert expiration is to mitigate the damage if the cert private key leaks, which happens a lot with big companies that have public-facing infrastructure and bad internal security practices (looking at you, Microsoft). As an individual, it is still worthwhile to update your certs every so often (e.g. every year) if for no other reason than to remind yourself how your SSL infrastructure is connected. It’s up to you whether or not it’s worth the effort to automate the cert distribution.

    I’ve used Letsencrypt to get certs for the proxy, but the traffic between the proxy and the backend is plain HTTP still. Do I need to worry about securing that traffic considering its behind a VPN?

    In spite of things you may have read, and the marketing of VPN services, a VPN is NOT a security tool. It is a privacy tool, as long as the encryption key for it is private.

    I’m not clear on what you mean by “between the proxy and the backend”. Is this referring to the VPS side, or your local network side, or both?

    Ultimately the question is, do you trust the other devices/services that might have access to the data before it enters the VPN tunnel? Are you certain that nothing else on the server might be able to read your traffic before it goes into the VPN?

    If you’re talking about a rented VPS from a public web host, the answer should be no. You have no idea what else might be running on that server, nor do you have control over the hypervisor or the host system.