What are the benefits of a server having multiple public IP addresses?
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You can ping yourself
If you keep pinging yourself you’ll go blind unless you enable spanning tree protocol
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I guess that's "a lot simpler" than 6 lines of config?
by factor of 3 obviously...
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
To go on top of the reverse DNS/mail comments, it can also be useful for running a service like codeburg pages, or some other program that handles its own virtual hosting and TLS, without interfering with your more traditional services.
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It's mostly a relic from an older time, it can be useful for more traditional services and situations that struggle with sharing public IPs. In theory, things like multiple IP addresses (and IPv6's near unlimited addresses) could be used to make things simpler -- you don't need reverse proxies and NAT and port forwarding (all of which were once viewed as excessive complexity if not outright ugly hacks instead of the virtual necessity they are today).
Each service would have its own dedicated public IP, you'd connect them up with IP routing the way the kernel gods intended, and everything would be straightforward, clear, and happy. If such a quantity of IPs were freely available, this would indeed be a simpler life in many ways. And yet it's such a distant fantasy now that it's understandable (though a little funny) to hear you describe it as "additional complexity" when, depending on how you look at it, the opposite is true...
From a modern perspective, you're absolutely right. The tables have really been turned, we have taken the limitation of IP addresses in stride, we have built elaborate systems of tools and layers of abstraction that not only turn these IP-shortage lemons into lemonade, the way we've virtualized the connections through featureful and easily-configurable software layers like private IP ranges, IP masquerading, proxies and tunnels can be used to achieve immense flexibility and reliable security. Most software now natively supports handling multiple services on a single IP or even a single port, and in some cases it requires it. This was not always the case.
It's sort of like the divide between hardware RAID and software RAID. Once upon a time, software RAID was slow, messy, confusing, unreliable, and distinctly inferior to "true" hardware RAID, which was plug-and-play with powerful configuration options. Nobody would willingly use software RAID if they had any other choice, the best RAID cards were sold for thousands of dollars and motherboards advertised how much hardware RAID they had built-in. But over time, as CPUs and software became faster and more powerful, the tide changed, and people started to realize that actually, hardware RAID was the one that left you tied to an expensive proprietary controller that could fail or become obsolete and leave your array a difficult to migrate or recover mess, whereas software RAID was reliable, predictable, upgradable, supporting a wide variety of disk types and layouts while still performing solidly and was generally far nicer to work with. It became the more common configuration, and found its way into almost every OS. You can now set up software RAID simply by clicking an option in a menu, even in Windows, and it basically works flawlessly without any additional thought.
Times change, we adapt to the technologies that are most common and that work the best in the situations we're using them in, and we make them better until they're not just a last resort anymore, but become a first choice, while the old way becomes a confusing anachronism. That's what multiple public IPs have become nowadays, for most purposes.
By "modern" do you mean "the late 90s"? HTTP 1.1 was adopted in '97 and allowed for the host header. NAT and port forwarding have been around since '94 - 2000ish.
Many services worked on any ports at the time as well. SMTP and DNS are probably the only ones that were (and remain) difficult to run on non-standard ports.
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
You got the basic idea from other posters, but there's also a lot of weird crap in there as well.
Basically you only need multiple IPs when dealing with services that only really operate on "well known ports". DNS and SMTP being the usual culprits. For most home users there this is no big deal - even if you wanted to host those services it's unlikely that you would need more than one ip to do so. HTTP solved this in '97 with HTTP/1.1 which allowed for host headers, which let's a single server host multiple sites.
This isn't something new that nginx solved.
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
It helps with spam campaigns.
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
It helps to download content (like YouTube videos for PeerTube instances) when you're rate limited
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
You can route traffic in different ways, for a high traffic endpoint hook an IP straight into nginx, while regular to via virtual opnSense router, that adds overhead but more flexible routing. Got PVE with virtual networking inside.
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Kids seem to think host name based routing is "new'... It worked fine in the 2000s with Apache.
Yup, I was reverse proxying early in my career, and I even built my own once for fun (I "hid" an SSH server on my HTTP server by looking at the first few bytes and proxying appropriately).
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For http(s), yes. Other services that don't support host routing, which is most of them, no.
Depending on the service, you totally can, provided they include some way to recognize them. For example, the first few bytes of SSH are unique, so I made a simple TCP server that would forward traffic to an HTTP(S) server or SSH server depending on those bytes.
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
You got a lot of relevant answers so I want to point out something else:
You're hosting your own services. By yourself. Fuck everyone with a broom who tries to gatekeep that. And I don't mean wooden side first.
Seriously, your question is on point here from my perspective and as long as it has a connection to running services by your own I personally would love more diversity in hosting solutions.
Personally, I'd love to see people share more about their provider agnostic opentofu deployment or someone who went all in on AWS lambdas for weird stuff.
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by factor of 3 obviously...
300% optimise! Give this coder a raise!
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My VPS provider is running a promotion where I can get up to 5 additional public IPv4 addresses for a one-time cost of $25 each. I have always only used a single public IP address per VPS. Would there be any advantage of having additional public IP addresses?
I know some people do not consider a VPS self-hosting, but this is the most relevant community I could think of and the question is also applicable for homelabs as well.
You can run a service on the same port with less processing overhead than a reverse proxy. Additionally it provides you some benefit in domain separation. For $25 I'd pick up one or two, couldn't hurt to have in the pocket and there are only so many of them afterall.
