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+date = 2022-03-24
+title = "Hardening a Public-Facing Home Server"
+description = "Learn some basic techniques to harden a home server and network."
++++
+
+## Post Updates
+
+> After reviewing this post today (2022-10-04), I noticed quite a few
+> gaps in my write-up and wanted to add a few things, even though this
+> blog is really just a retrospective and knowledge dump for myself. I
+> left things intact and simply crossed them out (~~like this~~) for
+> posterity.
+
+## Planning Data Flows & Security
+
+### My Personal Data Flow
+
+```txt
+                                                          ┌───────┐   ┌─────────────────┐
+                                                       ┌──► VLAN1 ├───► Private Devices │
+                                                       │  └───────┘   └─────────────────┘
+┌──────────┐   ┌────────┐   ┌──────────┐   ┌────────┐  │
+│ Internet ├───► Router ├───► Firewall ├───► Switch ├──┤
+└──────────┘   └────────┘   └──────────┘   └────────┘  │
+                                                       │  ┌───────┐   ┌───────────────┐
+                                                       └──► VLAN2 ├───► Public Server │
+                                                          └───────┘   └───────────────┘
+```
+
+### Thought Process
+
+To serve content from your home server and harden your security posture,
+you have to think about the transport of data from `server`
+to `client`.
+
+Let's start with the actual server itself. Think about the following:
+
+-   Do I have a firewall enabled? Do I need to update this to allow new
+    ports or IPs?
+-   Do I have an IPS/IDS that may prevent outside traffic?
+-   Do I have any other security software installed?
+-   Are the services hosted inside Docker containers, behind a reverse
+    proxy, or virtualized? If so, are they configured to allow outside
+    traffic?
+
+Once the data leaves the server, where does it go? In my case, it goes
+to a managed switch. In this case, I asked the following:
+
+-   What configurations is the switch using?
+-   Am I using VLANs?
+    -   Yes, I am using 802.1Q VLANs.
+-   Are the VLANs configured properly?
+    -   Yes, as shown in the [Switch](#switch) section below, I have a
+        separate VLAN to allow outside traffic to and from the server
+        alone. No other devices, except for a service port, and in that
+        VLAN.
+
+At this point, the data has been processed through the switch. Where
+does it go next? In my case, it's pretty simple: it goes to the
+router/modem device.
+
+-   Does my ISP block any ports that I need?
+    -   This is an important step that a lot of people run into when
+        self-hosting at home. Use an online port-checker tool for your
+        IP or call your ISP if you think ports are blocked.
+-   Is there a router firewall?
+    -   Yes, I checked that it's configured to allow the ports I need
+        to run my services publicly. Common web servers and reverse
+        proxies require ports 80 and 443, but other services like media
+        servers or games can require unique ports, so be sure to check
+        the documentation for your service(s).
+-   Are there any other settings affecting inbound/outbound traffic?
+    -   Schedules or access blocks
+    -   Static Routing
+    -   QoS
+    -   Port Forwarding
+    -   DMZ Hosting
+    -   Remote Management (this can sometimes mess with services that
+        also require the use of ports 80 and 443)
+
+Once the data leaves my router, it goes to the upstream ISP and can be
+accessed publicly.
+
+## Server
+
++The services I run on my server are installed straight into the OS,
+without any use of Docker or VMs, so I don't need any extra application
+configuration to make them accessible to the outside world.+
+
+As of 2022-10-04, the paragraph above is no longer true as I now run a
+reverse proxy with Nginx and host many services inside Docker. However,
+it doesn't change anything regarding this post as I still just need to
+open ports 80 & 443 and create the necessary website configuration
+files.
+
+When creating new services - either installed directly on bare metal or
+within something like Docker - I ensure that I read through the
+documentation thoroughly to understand a few key things: - What network
+activities should this app perform (if any)? Using which ports and
+protocols? - Does this app require any commands/services to be run as
+`root`? - Does this app log errors, authentication
+failures/successes, or anything else that would be useful for an
+investigation?
+
+For extra security, I use limit all incoming connections to SSH
+connections through my server firewall (`ufw`) and disable
+common SSH settings. After all of that, I use `fail2ban` as a
+preventative measure against brute-force login attempts.
+
+As another piece of security, you can randomize your SSH port to ensure
+that random scanners or attackers can't easily try to force their way
+into your network. For example, you can edit the port rules in your
+server to block all connection requests to port `22` but
+forward all remote connections from port `12345` to your
+server's port `22`. Then you just need to SSH to your
+network via your randomized port.
+
+### `ufw`
+
+To see how to configure `ufw`, see my other post: [Secure
+Your Network with the Uncomplicated
+Firewall](/blog/secure-your-network-with-the-uncomplicated-firewall/).
+
+The general notion with an on-device firewall is that you want to deny
+all incoming connections by default and then selectively open certain
+ports for services or users that you know need access.
+
+If you know that you will only be logging into this server from a
+certain set or list of IPs, you can always set the firewall to only
+allow connections to port 22 from those IPs.
+
+For a quick start to only allow SSH connections to the server, use this:
+
+```sh
+sudo ufw default deny incoming
+sudo ufw default allow outgoing
+sudo ufw allow 22
+sudo ufw enable
+```
+
+![ufw](https://img.cleberg.net/blog/20220324-hardening-a-public-facing-home-server/ufw.png)
+
+### `ssh`
+
+1.  Using SSH Keys
+
+    First, make sure you have an SSH keypair generated on the device(s)
+    that you'll be using to log in to the server. If you don't have an
+    SSH key, run this command:
+
+    ```sh
+    ssh-keygen
+    ```
+
+    Now that we have an SSH key, copy it to the server with the
+    following command, which will ask for the user's password before
+    accepting the key:
+
+    ```sh
+    ssh-copy-id my_user@my_server
+    ```
+
+    If you have multiple keys, you'll need to specify which to use.
+    After it's complete, `ssh` back into the server as that
+    user and make sure it doesn't ask for a password.
+
+2.  Disable Password & Root Authentication
+
+    Now that we can access the server without a password, we will
+    disable password authentication and disable anyone from using
+    `ssh` to login as `root`.
+
+    To do this, open the `sshd_config` file:
+
+    ```sh
+    sudo nano /etc/ssh/sshd_config
+    ```
+
+    You'll need to update the parameters to the values below. If one of
+    these rules is commented-out or doesn't exist, create the rule at
+    the bottom of the file.
+
+    ```config
+    PermitRootLogin no
+    PasswordAuthentication no
+    PubkeyAuthentication yes
+    ```
+
+    Finally, restart the `ssh` service:
+
+    ```sh
+    sudo systemctl restart sshd.service
+    ```
+
+    To test that everything's working so far, open ANOTHER terminal and
+    try logging in as `root` over SSH. It is very important
+    that you keep your current SSH session open and test with an
+    additional session, or you will lock yourself out at some point and
+    will need to use a recovery method (e.g., hooking monitor up to home
+    server) to get yourself back in.
+
+3.  Enable MFA for `ssh`
+
+    This part is optional, but I highly recommend it. So far, we've
+    ensured that no one can log into our user on the server without
+    using our secret key, and we've ensured that no one can log in
+    remotely as `root`. Next, you can enable MFA
+    authentication for `ssh` connections.
+
+    This process involves editing a couple files and installing an MFA
+    package, so I will not include all the details in this post. To see
+    how to configure MFA for `ssh`, see my other post:
+    [Enabling MFA for SSH](/blog/enable-totp-mfa-for-ssh/).
+
+    ![SSH
+    MFA](https://img.cleberg.net/blog/20220324-hardening-a-public-facing-home-server/ssh_mfa.png)
+
+### `fail2ban`
+
+I haven't written a post on how I use `fail2ban`, but it's
+quite simple. I use the default `sshd` jail, but you can
+always create new jails for respective applications or ports. For
+example, if you use Nginx as your web server, you can use the
+`nginx-http-auth` jail.
+
+In order to get it up and running, use the following commands:
+
+```sh
+sudo apt install fail2ban
+sudo fail2ban-client start sshd
+sudo fail2ban-client status sshd
+```
+
+This should be used as a last-resort defense and shouldn't be a
+replacement for the security measures mentioned above.
+
+![fail2ban](https://img.cleberg.net/blog/20220324-hardening-a-public-facing-home-server/fail2ban.png)
+
+## Switch
+
+Between the router and any local devices is my managed switch, which is
+used to create VLANs. The example below shows how I would isolate the
+VLANs if I were starting to host a single service at home.
+
+### 802.1Q VLAN Configuration
+
+In this configuration, port 8 is the public server that needs to be
+accessed from the outside. Port 23 is my 'dedicated service port' for
+this server. In order to SSH to this server, I need to plug my laptop
+into port 23 or else I cannot SSH. Otherwise, I'd need to hook up a
+monitor and keyboard directly to the server to manage it.
+
+  VLAN ID   VLAN Name   Member Ports   Tagged Ports   Untagged Ports
+  --------- ----------- -------------- -------------- ----------------
+  1         Default     1-24                          1-24
+  2         Server      1,8,23                        1,8,23
+
+### 802.1Q VLAN PVID Setting
+
+Once the VLAN is created, I simply add the `VLAN ID` of
+`2` as the `PVID` for any related ports (in this
+case, see that ports `8` and `23` have a PVID of
+`2`).
+
+  Port   PVID
+  ------ ------
+  1      1
+  2      1
+  3      1
+  4      1
+  5      1
+  6      1
+  7      1
+  8      2
+  9      1
+  10     1
+  11     1
+  12     1
+  13     1
+  14     1
+  15     1
+  16     1
+  17     1
+  18     1
+  19     1
+  20     1
+  21     1
+  22     1
+  23     2
+  24     1
+
+## Router
+
+On my router, the configuration was as easy as opening the firewall
+settings and unblocking the ports I needed for my services (e.g.,
+HTTP/S, Plex, SSH, MySQL, etc.).
+
++Since I'm relying on an ISP-provided modem/router combo for now (not
+by choice), I do not use any other advanced settings on my router that
+would inhibit any valid traffic to these services.+
+
+The paragraph above regarding the ISP-owned router is no longer accurate
+as I now use the Ubiquiti Unifi Dream Machine Pro as my router. Within
+this router, I enabled port forwarding/firewall rules, segregate the
+network based on the device, and enable traffic restrictions (e.g.,
+silently drop traffic from certain countries and threat categories).
+
+If you have the option with your ISP, I recommend using a personal
+router with software that you are familiar with so that you can explore
+all the options available to you.
+
+## Physical Security
+
+One large piece of self-hosting that people generally don't discuss
+online is physical security. However, physical security is very
+important for everyone who hosts a server like this. Exactly *how*
+important it is depends on the server use/purpose.
+
+If you self-host customer applications that hold protected data (HIPAA,
+GDPR, COPPA, etc.), then physical security is extremely important and
+cannot be ignored. If you simply host a blog and some hobby sites, then
+it's a relatively minor consideration, but one you still need to think
+about.
+
+### Location
+
+The first consideration is quite simple: location. - Is the server
+within a property you own or housed on someone else's property? - Is it
+nearby (in your house, in your work office, in your neighbor's garage,
+in a storage unit, etc.)? - Do you have 24/7 access to the server? - Are
+there climate considerations, such as humidity, fires, tornadoes,
+monsoons? - Do you have emergency equipment nearby in case of emergency?
+
+### Hardware Ownership
+
+Secondly, consider the hardware itself: - Do you own the server in its
+entirety? - Are any other users able to access the server, even if your
+data/space is segregated? - If you're utilizing a third party, do they
+have any documentation to show responsibility? This could be a SOC 1/2/3
+report, ISO compliance report, internal security/safety documentation.
+
+### Physical Controls
+
+Regardless of who owns the hardware, ensure that there are adequate
+safeguards in place, if necessary. These usually don't apply to small
+home servers and are usually covered already if you're utilizing a
+third party.
+
+These can include: - Server bezel locks - Server room locks - physical,
+digital, or biometric authentication - Security cameras - Raised
+floors/lowered ceilings with proper guards/gates in-place within the
+floors or ceilings - Security personnel - Log sheets and/or guest badges