Host a den

Dens, installed on Linux or Windows, can also host one den; the Flatpak can’t. The den lives on your computer, and members connect to it over the internet. This guide covers the router and domain parts too, assuming you’ve never done either.

What you need

A computer that stays on. The den is only up while it runs. A normal PC is enough, or a server: Host on a server sets one up, and moves a den you host now onto it.
Upload speed. Messages go out once to every member online, and calls and screen shares once to every member in them. A new den’s limits need about 20 Mbps of upload when every call is full; you can lower or raise them.
A domain name, such as den.example.com, which members connect to. Any registrar sells them, usually for $10 to $20 a year.
Your router’s settings, to forward four ports to this computer.

Dens is one program with its database and media tools built in, so besides Dens, a den needs only Caddy, a small web server that the steps below set up.

Turn hosting on

Install Dens if you haven’t, and open it (dens open). In Settings, under System, turn on Host a den on this computer. It asks for your local password, since it opens Dens to the internet: the den’s own port, which Caddy passes connections on to, and the ports calls use.

If another program already uses one of those ports, the setting says which, and how to give the den another: run the installer again with the matching option, such as --den-port (-DenPort on Windows).

You can turn hosting off there too. Members can’t reach the den until you turn it back on, and nothing in it is lost.

Create the den

The home page now shows Create your den: give it a name, its public address (https:// and your domain), and your owner account, with a username, a display name and a den password.

This works before the steps below, since Dens reaches its own den directly.

Point your domain at your home

In your domain’s DNS settings, add an A record for your den’s name, pointing at your home’s public IP address (searching “what is my IP” from this computer tells you). If your connection has an IPv6 address too, add an AAAA record for it.

A home connection’s address can change. Many routers and DNS providers offer dynamic DNS, which keeps the record up to date for you.

Set up Caddy

Caddy gets your den a free HTTPS certificate, and passes connections on to Dens. Use your own domain in place of den.example.com.

Install it from your distribution:

Distribution	Command
Debian, Ubuntu, Mint, Pop!_OS	`sudo apt install caddy`
Fedora	`sudo dnf install caddy`
Arch, CachyOS	`sudo pacman -S caddy`
Bazzite	`rpm-ostree install caddy`, then restart

Then give it your den, and start it:

sudo tee /etc/caddy/Caddyfile <<'EOF'
den.example.com {
	reverse_proxy 127.0.0.1:8485
}
EOF
sudo systemctl enable caddy
sudo systemctl restart caddy

If your system runs a firewall, let the den’s ports through it. Fedora and Bazzite do:

sudo firewall-cmd --permanent --add-service=http --add-service=https
sudo firewall-cmd --permanent --add-port=7881/udp --add-port=7882/tcp
sudo firewall-cmd --reload

Download Caddy for Windows from caddyserver.com, make a folder C:\Caddy, and put caddy.exe in it. Then, in an admin terminal:

@"
den.example.com {
	reverse_proxy 127.0.0.1:8485
}
"@ | Set-Content C:\Caddy\Caddyfile
New-Service -Name caddy -BinaryPathName '"C:\Caddy\caddy.exe" run --config C:\Caddy\Caddyfile --adapter caddyfile' -StartupType Automatic
Start-Service caddy
New-NetFirewallRule -DisplayName Caddy -Direction Inbound -Program C:\Caddy\caddy.exe -Action Allow

The Dens installer already let the den’s call ports through the Windows firewall. Nothing answers on them until you turn hosting on.

Forward the ports

In your router’s settings, often under port forwarding, forward these to this computer:

Port	Protocol	For
80	TCP	Caddy getting its certificate
443	TCP	Members connecting
7881	UDP	Voice and screen share
7882	TCP	Voice and screen share, where UDP is blocked

Routers differ too much to show here: search for your router’s model and “port forwarding”. While you’re there, reserve this computer’s local address (often called a DHCP reservation), so the forwarding keeps pointing at it.

Some internet providers share one public address among many customers (called CGNAT), and then forwarding can’t work. A small rented server (a VPS) with an address of its own can host the den instead (Host on a server).

Invite someone, and test a call

In Dens, open the den’s Manage, then Invites, and create one. Send it to a friend.

Your own calls work before any port is forwarded, so test from outside your home: have your friend join a call with you, or join from a laptop on your phone’s hotspot. Calls go straight to the address your domain points at, so a tunnel or CDN service that carries your den’s website can’t carry its calls.

Running the den

Everything here is in the den’s Manage, under This den.

Roles. Members read and post, DM, call and upload. Moderators also make invites, remove and ban members, delete members’ messages, manage channels, and see staff-only channels. The owner also picks moderators and sets the den’s limits. Staff act only on people of a lower rank.
Invites are the only way in. Each one expires, and works a set number of times.
Removing and banning. Removing someone signs them out everywhere. A ban also keeps their username out, and can delete their recent messages. Dens keeps no IP addresses, so someone banned can come back under a new name with a new invite: revoke the invite they used.
Limits cap file sizes and storage, and how big calls and screen shares get. The calls section shows the upload they need when full; lower them if calls stutter.
Auto-delete, off unless you turn it on, deletes messages older than a number of days, in channels and DMs. Members see the setting. A backup keeps what it held until you delete the backup.
A new address. Change it in General, and keep the old name pointing at the den for a while, so members who were offline find the new one.

What hosting costs you

Mostly upload. Dens keeps it small: members pick up where they left off instead of reloading everything, who’s online goes out in batches, and pictures go out as previews until someone opens them. A den is sized for about a thousand members, 500 of them online at once.

Your den updates along with the Dens that hosts it: dens update updates both. If you’d rather keep them apart, host the den from an install of its own.

One install hosts one den. A second den on the same computer is a second instance: run the installer again with --instance and a name, and ports of its own (--client-port, --den-port, --media-udp-port and --media-tcp-port; on Windows, -Instance, -ClientPort and so on), turn hosting on in its settings, and give Caddy a second site.

Join a den Host on a server