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• Using WireGuard to host services at home
  • It's only NATural
  • WireGuard comes to help
  • Setting up on the server
  • Setting up at your home
  • A few notes about security
• Ubuntu debuginfod and source code indexing
  • The problem
  • The solution…
  • … but not a perfect one
  • … especially if you're using LTO
  • Your feedback is important to us
• Novo blog, novos links
• New blog, new links

DONE Using WireGuard to host services at home   english howto selfhost wireguard debian

CLOSED: [2023-05-23 Tue 00:56]

It's been a while since I had this idea to leverage the power of WireGuard to self-host stuff at home. Even though I pay for a proper server somewhere in the world, there are some services that I don't consider critical to put there, or that I consider too critical to host outside my home.

It's only NATural

With today's ISP packages for end users, I find it very annoying the amount of trouble they create when you try to host anything at home. Dynamic IPs, NAT/CGNAT, port-blocking, traffic shapping are only a few examples of methods or limitations that prevent users from making local services reachable in a reliable way from outside.

WireGuard comes to help

If you already pay for a VPS or a dedicated server somewhere, why not use its existing infrastructure (and public availability) in your favour? That's what I thought when I started this journey.

My initial idea was to use a reverse proxy to redirect external requests to the service running at my home. But how could I make sure that these requests reach my dynamic-IP-behind-a-NAT-behind-another-NAT? Well, let's create a tunnel! WireGuard is the perfect tool for that because of many things: it's stateless, very performant, secure, and requires very little configuration.

Setting up on the server

On the server side (i.e., VPS or dedicated server), you will create the first endpoint. Something like the following should do:

[Interface]
PrivateKey = PRIVATE_KEY_HERE
Address = 10.0.0.1/32
ListenPort = 51821

[Peer]
PublicKey = PUBLIC_KEY_HERE
AllowedIps = 10.0.0.2/32
PersistentKeepalive = 10

A few interesting points to note:

• The Peer section contains information about the home service that will be configured below.
• I'm using PersistentKeepalive because I have a dynamic IP at my home. If you have a static IP, you could get rid of PersistentKeepalive and specify an Endpoint here (don't forget to set a ListenPort below, in the Interface section).
• Now you have an IP where you can forward requests to. If we're talking about HTTP traffic, Apache and nginx are absolutely capable of doing it. If we're talking about other kind of traffic, you might want to look into other utilities, like HAProxy, Traefik and others.

Setting up at your home

At your home, you will configure the peer:

[Interface]
PrivateKey = PRIVATE_KEY_HERE
Address = 10.0.0.2/32

[Peer]
PublicKey = PUBLIC_KEY_HERE
AllowedIps = 10.0.0.1/32
Endpoint = YOUR_SERVER:51821
PersistentKeepalive = 10

A few notes about security

I would be remiss if I didn't say anything about security, especially because we're talking about hosting services at home. So, here are a few recommendations:

• Make sure to put your services in a separate local network. Using VLANs is also a good option.
• Don't run services on your personal (or work!) computer, even if they'll be running inside a VM.
• Run a firewall on the WireGuard interface and make sure that you only allow traffic over the required ports.

Have fun!

DONE Ubuntu debuginfod and source code indexing   english ubuntu debuginfod debian free_software gdb

CLOSED: [2023-05-13 Sat 16:43]

You might remember that in my last post about the Ubuntu debuginfod service I talked about wanting to extend it and make it index and serve source code from packages. I'm excited to announce that this is now a reality since the Ubuntu Lunar (23.04) release.

The feature should work for a lot of packages from the archive, but not all of them. Keep reading to better understand why.

The problem

While debugging a package in Ubuntu, one of the first steps you need to take is to install its source code. There are some problems with this:

• apt-get source required dpkg-dev to be installed, which ends up pulling in a lot of other dependencies.
• GDB needs to be taught how to find the source code for the package being debugged. This can usually be done by using the dir command, but finding the proper path to be is usually not trivial, and you find yourself having to use more "complex" commands like set substitute-path, for example.
• You have to make sure that the version of the source package is the same as the version of the binary package(s) you want to debug.
• If you want to debug the libraries that the package links against, you will face the same problems described above for each library.

So yeah, not a trivial/pleasant task after all.

The solution…

Debuginfod can index source code as well as debug symbols. It is smart enough to keep a relationship between the source package and the corresponding binary's Build-ID, which is what GDB will use when making a request for a specific source file. This means that, just like what happens for debug symbol files, the user does not need to keep track of the source package version.

While indexing source code, debuginfod will also maintain a record of the relative pathname of each source file. No more fiddling with paths inside the debugger to get things working properly.

Last, but not least, if there's a need for a library source file and if it's indexed by debuginfod, then it will get downloaded automatically as well.

… but not a perfect one

In order to make debuginfod happy when indexing source files, I had to patch dpkg and make it always use -fdebug-prefix-map when compiling stuff. This GCC option is used to remap pathnames inside the DWARF, which is needed because in Debian/Ubuntu we build our packages inside chroots and the build directories end up containing a bunch of random cruft (like /build/ayusd-ASDSEA/something/here). So we need to make sure the path prefix (the /build/ayusd-ASDSEA part) is uniform across all packages, and that's where -fdebug-prefix-map helps.

This means that the package must honour dpkg-buildflags during its build process, otherwise the magic flag won't be passed and your DWARF will end up with bogus paths. This should not be a big problem, because most of our packages do honour dpkg-buildflags, and those who don't should be fixed anyway.

… especially if you're using LTO

Ubuntu enables LTO by default, and unfortunately we are affected by an annoying (and complex) bug that results in those bogus pathnames not being properly remapped. The bug doesn't affect all packages, but if you see GDB having trouble finding a source file whose full path starts without /usr/src/..., that is a good indication that you're being affected by this bug. Hopefully we should see some progress in the following weeks.

Your feedback is important to us

If you have any comments, or if you found something strange that looks like a bug in the service, please reach out. You can either send an email to my public inbox (see below) or file a bug against the ubuntu-debuginfod project on Launchpad.

DONE Novo blog, novos links   pt_br portugues

CLOSED: [2023-04-20 Thu 21:38]

Eu sei que não posto aqui há algum tempo, mas gostaria de avisar os meus leitores (hã!?) de que eu troquei a engine do blog pro Hugo. Além disso, vocês vão notar que as URLs dos posts mudaram também (elas não têm mais data, agora são só compostas pelo nome do post; mas veja abaixo), e que também houve uma mudança na tag pt_br: futuramente eu pretendo parar de postar coisas nela, e vou postar somente usando a tag portugues. Se você acompanha o RSS/ATOM da tag pt_br, por favor atualize o link.

As URLs antigas ainda vão funcionar porque elas estão sendo redirecionadas pro lugar correto (cortesia do mod_rewrite). De qualquer modo, se você salvou alguma URL de um post antigo, sugiro que a atualize.

No mais, tudo deve funcionar "como de costume" (TM). Estou postando direto do Emacs (usando ox-hugo), e criei um setup bacana no Sourcehut pra automaticamente publicar os posts assim que eu der o push deles pro git. Hm, isso na verdade seria um bom tópico pra um post…

DONE New blog, new links   en_us english

CLOSED: [2023-04-20 Thu 21:26]

I know I haven't posted in a while, but I'd like to let my readers (who!?) know that I've switched my blog's engine to Hugo. Along with that change, there are also changes to post URLs (no more dates, only the post name; but see below) and also a change to the en_us tag: eventually, I will stop posting things under it and start posting solely under english. If you're subscribed to the en_us RSS/ATOM feed, please update it accordingly.

The old URLs should still work because they're being redirected to the correct path now (thanks, mod_rewrite). Either way, if you have bookmarked some old post URL I'd suggest that you update it.

Other than that, everything should be "the same" (TM). I'm posting from Emacs (using ox-hugo), and made quite a cool setup with Sourcehut in order to automatically publish posts when I push them to the git repo. Hm, his would actually be a good topic for a post…