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| -rw-r--r-- | docs/advanced/security/firewall.md | 84 | ||||
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diff --git a/docs/advanced/certificates.md b/docs/advanced/certificates.md new file mode 100644 index 000000000..cc506bdbd --- /dev/null +++ b/docs/advanced/certificates.md @@ -0,0 +1,108 @@ +# Provisioning TLS certificates + +As explained in the [deployment considerations](../getting_started/index.md), federation requires the use of TLS as most instances refuse to federate over unencrypted transports. + +GoToSocial comes with built-in support for provisioning and renewing its own TLS certificates through Lets Encrypt. This guide looks at how you can provision your own certificates independently from GoToSocial. This can be useful if you want full control over how the certificates are provisioned, or because you're using a [reverse proxy](../getting_started/reverse_proxy/index.md) which is doing TLS termination. + +There are a few different ways you can get TLS certificates: + +* Buy them from a vendor, typically valid for 2 years +* Get them from your cloud provider, validity depends on their product constraints +* Get them from an [ACME](https://en.wikipedia.org/wiki/Automatic_Certificate_Management_Environment)-compatible provider like Lets Encrypt, typically valid for 3 months at a time + +In this guide we'll only look at option 3, an ACME-compatible vendor. + +## General approach + +The way you'll provision certificates through Lets Encrypt is: + +* Install an ACME client on your server +* Configure the ACME client to provision your certificates +* Configure a piece of software to use those certificates +* Enable a timer/cron to regularly renew the certificates +* Signal to the necessary applications they need to reload or restart to pick up the new certificates + +Certificates are provisioned [using a challenge](https://letsencrypt.org/sv/docs/challenge-types/), a way to verify that you're requesting a certificate for a domain you control. You'll typically use one of: + +* HTTP challenge +* DNS challenge + +The HTTP challenge requires serving certain files on port 80 on the domains you're requesting a certificate for under the `/.well-known/acme/` path. This is the default challenge type. + +The DNS challenge happens entirely out of band but requires you to update a DNS TXT record. This approach is only feasible if your DNS registrar provides an API through which you can modify DNS records so that your ACME client can complete this challenge. + +## Clients + +The official Lets Encrypt client is [certbot](https://certbot.eff.org/) and it's usually packaged in [your (Linux) distribution](https://repology.org/project/certbot/versions) of choice. Certain reverse proxies like Caddy and Traefik have built-in support for provisioning certificates using the ACME protocol. + +A couple of other clients of note that you can consider using: + +* [acme-client](https://man.openbsd.org/acme-client.1) for OpenBSD using the privilege separation features of the platform +* [lacme](https://git.guilhem.org/lacme/about/), which is built with process isolation and minimal privileges in mind in the same vein as acme-client but for Linux +* [Lego](https://github.com/go-acme/lego), an ACME client and library written in Go +* [mod_md](https://httpd.apache.org/docs/2.4/mod/mod_md.html), when using Apache 2.4.30+ + +### DNS challenge + +For the DNS challenge, the API of your registrar needs to be supported by your ACME client. Though certbot has a few plugins for popular providers, you probably want to look at the [dns-multi](https://github.com/alexzorin/certbot-dns-multi) plugin instead. It leverages [Lego](https://github.com/go-acme/lego) under the hood which supports a much wider array of providers. + +## Configuration + +There are 3 configuration options that are important: + +* [`letsencrypt-enabled`](../configuration/tls.md) controls if GoToSocial will try to provision its own certificates +* [`tls-certificate-chain`](../configuration/tls.md) filesystem path where GoToSocial can find the TLS certificate chain + the public key +* [`tls-certificate-key`](../configuration/tls.md) filesystem path where GoToSocial can find the associated TLS private key + +### Without reverse proxy + +When running GoToSocial directly exposed to the internet, but you still want to use your own certificates you can set the following options: + +```yaml +letsencrypt-enabled: false +tls-certificate-chain: "/path/to/combined-certificate-chain-public.key" +tls-certificate-key: "/path/to/private.key" +``` + +This disables the built-in provisioning of certificates through Lets Encrypt and tells GoToSocial where to find the certificates on disk. + +!!! tip + Restart GoToSocial after renewing your certificates. It won't pick up on certificate rotation by itself when they are provided like this. + +### With reverse proxy + +When running GoToSocial behind a [reverse proxy](../getting_started/reverse_proxy/index.md) which you also use for TLS termination, you'll need the following instead: + +```yaml +letsencrypt-enabled: false +tls-certificate-chain: "" +tls-certificate-key: "" +``` + +It's important to ensure the `tls-certificate-*` options are unset or set to the empty string. Otherwise GoToSocial will attempt to handle TLS itself. + +!!! danger "Protocol configuration option" + Do **not** change the [`protocol`](../configuration/general.md) configuration option to `http`. This should only ever by set to `http` for development purposes. It needs to be set to `https` even when running behind a TLS-terminating reverse proxy. + +You'll also want to change the [`port`](../configuration/general.md) GoToSocial binds on, so it no longer tries to use port 443. + +To configure TLS in your reverse proxy, please refer to their documentation: + +* [nginx](https://docs.nginx.com/nginx/admin-guide/security-controls/terminating-ssl-http/) +* [apache](https://httpd.apache.org/docs/2.4/ssl/ssl_howto.html) +* [Traefik](https://doc.traefik.io/traefik/https/tls/) +* [Caddy](https://caddyserver.com/docs/caddyfile/directives/tls) + +!!! tip + When configuring TLS in your reverse proxy, ensure you configure a reasonably modern set of compatible versions and ciphers. You can use the "Intermediate" configuration from the [Mozilla SSL Configuration Generator](https://ssl-config.mozilla.org/). + + Check the documentation of your reverse proxy on whether you have to reload or restart it after certificates have changed. Not all reverse proxies detect this. + +## Guides + +There are a number of good resources on the internet explaining how to set all of this up. + +* [ArchWiki entry](https://wiki.archlinux.org/title/certbot) on certbot +* [Gentoo wiki entry](https://wiki.gentoo.org/wiki/Let%27s_Encrypt) on Lets Encrypt +* [Linode guide](https://www.linode.com/docs/guides/enabling-https-using-certbot-with-nginx-on-fedora/) on certbot for Fedora, RHEL/CentOS, Debian and Ubuntu +* Digital Ocean guides on Lets Encrypt on Ubuntu 22.04 with [nginx](https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-ubuntu-22-04) or [apache](https://www.digitalocean.com/community/tutorials/how-to-secure-apache-with-let-s-encrypt-on-ubuntu-22-04) diff --git a/docs/advanced/index.md b/docs/advanced/index.md index f196b191b..351190227 100644 --- a/docs/advanced/index.md +++ b/docs/advanced/index.md @@ -8,7 +8,9 @@ We consider these topics advanced because applying them incorrectly does have th * [Split-domain deployment (API vs. account domain)](host-account-domain.md) * [Using an HTTP proxy for client/outgoing requests](outgoing-proxy.md) +* [Provisioning TLS certificates](certificates.md) * [Caching API responses](caching/api.md) * [Serving and caching assets and media from local storage](caching/assets-media.md) * [Process sandboxing](security/sandboxing.md) +* [Firewall configuration](security/firewall.md) * [Tracing](tracing.md) diff --git a/docs/advanced/security/firewall.md b/docs/advanced/security/firewall.md new file mode 100644 index 000000000..c94dce75a --- /dev/null +++ b/docs/advanced/security/firewall.md @@ -0,0 +1,84 @@ +# Firewall + +You should deploy a firewall on your instance to close off any open ports and give you a mechanism to ban potentially misbehaving clients. Many firewall frontends will also automatically install some rules that block obvious malicious packets. + +It can be helpful to deploy tools that monitor your log files for certain patterns and automatically ban clients exhibiting certain behaviour. This can be use to monitor your SSH and web server access logs for things like SSH brute-force attacks. + +## Ports + +For GoToSocial, you'll want to ensure port `443` remains open. Without it, nobody will be able to reach your instance. Federation will fail and client apps won't be able to work at all. + +If you [provision TLS certificates](../certificates.md) using ACME or GoToSocial's built-in Lets Encrypt support, you'll also need port `80` to be open. + +In order to access your instance over SSH, you'll need to keep the port your SSH daemon is bound on open too. By default this is port `22`. + +## ICMP + +[Internet Control Message Protocol](https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol) are exchanged between machines in order to detect certain network conditions or troubleshoot things. Many firewalls have a tendency of blocking ICMP entirely but this is undesirable. A few ICMP types should be allowed and you can use your firewall to configure rate limiting for them instead. + +### IPv4 + +In order for things to work reliably, your firewall must allow: + +* ICMP Type 3: "Destination Unreachable" and also aids in Path-MTU Discovery +* ICMP Type 4: "Source Quench" + +If you want to be able to ping things or be pinged, you should also allow: + +* ICMP Type 0: "Echo Reply" +* ICMP Type 8: "Echo Request" + +For traceroute to work, it can be helpful to also allow: + +* ICMP Type 11: "Time Exceeded" + +### IPv6 + +ICMP is heavily relied on by all parts of the IPv6 stack and things will break in exciting and hard to debug ways if you block it. [RFC 4890](https://www.rfc-editor.org/rfc/rfc4890) was specifically written to address this and is worthwhile to review. + +Roughly speaking, you must always allow: + +* ICMP Type 1: "Destination Unreachable" +* ICMP Type 2: "Packet Too Big" +* ICMP Type 3, code 0: "Time Exceeded" +* ICMP Type 4, code 1, 2: "Parameter Problem" + +For ping, you should allow: + +* ICMP Type 128: "Echo Request" +* ICMP Type 129: "Echo Response" + +## Firewall configuration + +On Linux, firewalling is typically done using either [iptables](https://en.wikipedia.org/wiki/Iptables) or the more modern and faster [nftables](https://en.wikipedia.org/wiki/Nftables) as the backend. Most distributions are switching to nftables and many firewall frontends can be configured to use nftables instead. You'll need to refer to your distribution's documentation on the matter, but typically there will be an `iptables` or `nftables` service your init-system can start with a predefined location to load firewall rules from. + +Doing this by hand using raw iptables or nftables rules offers the most control but can be challenging if you're not familiar with these systems. In order to help with that, a number of configuration frontends exist that you can use. + +On the Debian and Ubuntu as well as openSUSE family of distributions, UFW is commonly used. It's a simple firewall front-end and many tutorials targeting those distributions will be using it. + +For the Red Hat/CentOS family of distributions, firewalld is typically used. It's a much more advanced firewall configuration utility which also has a desktop GUI and [Cockpit integration](https://cockpit-project.org/). + +Despite distribution preferences, you can use UFW, firewalld or something else entirely with any Linux distribution. + +* [Ubuntu Wiki](https://wiki.ubuntu.com/UncomplicatedFirewall?action=show&redirect=UbuntuFirewall) on UFW +* [ArchWiki](https://wiki.archlinux.org/title/Uncomplicated_Firewall) on UFW +* Digital Ocean guide on [using UFW with Ubuntu 22.04](https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-22-04) +* [firewalld](https://firewalld.org/) project homepage and documentation +* [ArchWiki](https://wiki.archlinux.org/title/firewalld) on firewalld +* [Using and configuring firewalld](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/configuring_firewalls_and_packet_filters/using-and-configuring-firewalld_firewall-packet-filters) from Red Hat +* Linode guide [on using firewalld](https://www.linode.com/docs/guides/introduction-to-firewalld-on-centos/) + +## Brute-force protection + +[fail2ban](https://www.fail2ban.org) and [SSHGuard](https://www.sshguard.net/) can be set up to monitor your log files for attempts to brute-force logins and other malicious behaviour. They can be configured to automatically insert firewall rules to block malicious IP addresses, either for a specific period of time or even indefinitely. + +SSHGuard was initially designed just for SSH, but nowadays supports a variety of services. Fail2ban tends to support anything you can generate consistent log lines for, whereas SSHGuard's signature approach can catch more sophisticated or stealthy attacks as it computes an attack score over time. + +Both SSHGuard and fail2ban ship with "backends" that can target iptables and nftables directly, or work with your frontend of choice like UFW or firewalld on Linux or pf on \*BSD. Make sure you review their documentation on how to correctly configure it. + +* [ArchWiki](https://wiki.archlinux.org/title/Fail2ban) on fail2ban +* DigitalOcean guide on how to protect SSH with [fail2ban on Ubuntu](https://www.digitalocean.com/community/tutorial_collections/how-to-protect-ssh-with-fail2ban) +* Linode guide on how to [secure your server with fail2ban](https://www.linode.com/docs/guides/using-fail2ban-to-secure-your-server-a-tutorial/) +* [ArchWiki](https://wiki.archlinux.org/title/sshguard) on sshguard +* [FreeBSD manual](https://man.freebsd.org/cgi/man.cgi?query=sshguard&sektion=8&manpath=FreeBSD+13.2-RELEASE+and+Ports) for sshguard +* [SSHGuard setup](https://manpages.ubuntu.com/manpages/lunar/en/man7/sshguard-setup.7.html) manual for Ubuntu diff --git a/docs/advanced/security/index.md b/docs/advanced/security/index.md index 63ee73c9a..2ff47284a 100644 --- a/docs/advanced/security/index.md +++ b/docs/advanced/security/index.md @@ -3,8 +3,9 @@ These guides cover improving the security posture of your GoToSocial deployment. They don't involve tweaking settings in GoToSocial, but rather additional things you can do to better lock down your instance. !!! note - Anything in these guides is meant to ehance the security of your GoToSocial deployment; they are not a replacement for good security practices like keeping your systems patched and up to date. + Anything in these guides is meant to enhance the security of your GoToSocial deployment; they are not a replacement for good security practices like keeping your systems patched and up to date. ## Guides * [Sandboxing the GoToSocial binary](sandboxing.md) +* [Firewall configuration](firewall.md) |