An Iskra box at home

Your server, your choice. Iskra gets nothing from any of this; this is just a guide.

A small computer that's always on is a great home for your group's Iskra server: an old PC or laptop, a mini PC, or a Raspberry Pi. It costs a few euros of electricity a year, everything stays in your home, and nobody has to keep their gaming PC running so friends can chat.

This guide covers picking the box, installing Iskra, starting it with the computer, letting friends in from the internet, updates, backups and keeping the power bill small. The full reference is Hosting reference.

1. Pick a box#

Anything from the last ten years or so works for a friend group. What matters is that it's 64-bit and can stay on.

Not supported: 32-bit systems (Raspberry Pi OS 32-bit, armv7l, old 32-bit Windows). On a Raspberry Pi, check with uname -m: it must say aarch64; if it says armv7l, install the 64-bit Raspberry Pi OS.

How big? 1 GB of memory is enough for a group of friends (the cheapest cloud servers Iskra runs on have 1 GB); 2 GB or more is comfortable. Disk space is mostly the files people share, plus about 100 MB if someone uses live captions. A wired network cable is better than Wi-Fi for voice.

Voice (LiveKit) is in every package: nothing else to install.

A Raspberry Pi: microSD card or SSD#

Both work. Pick what you have:

• A good microSD card works fine. Use one from a known brand marked A2 (32–64 GB is plenty). In Raspberry Pi Imager choose your Pi, Raspberry Pi OS Lite (64-bit) (no desktop needed) and the card. Let Imager set a host name, your user and password, and turn on SSH. Put the card in the Pi and start it.
• An SSD is the upgrade if you want it to last for years or run faster: an NVMe SSD on an M.2 HAT for a Pi 5 (the official M.2 HAT+ or a similar board, with the official 27 W power supply), or a USB 3 SSD in a blue USB 3 port on a Pi 4 or 5. Steps below.

Either way, do Make it last and set up encrypted backup copies on a USB stick or another computer: then even a dead card is a 5-minute fix.

Putting the system on an SSD (Raspberry Pi's own guides: boot from NVMe, boot order):

1. Write the system to the SSD with Imager, as for a card. A USB SSD can be written from your PC. An NVMe SSD sits in the Pi, so start the Pi once from a microSD card with Raspberry Pi OS, then run Imager on the Pi and pick the NVMe drive.
2. Update the bootloader (on the Pi running from the card): sudo rpi-eeprom-update shows its date. For NVMe it must be December 6, 2023 or later; if it's older, run sudo raspi-config → Advanced Options → Bootloader Version → Latest, then sudo rpi-eeprom-update -a and sudo reboot.
3. Boot from the SSD: sudo raspi-config → Advanced Options → Boot Order → the option with NVMe/USB first → Finish, and reboot. Then take the card out: the Pi starts from the SSD.
4. Pi 5 with a USB SSD on a power supply that isn't the official 27 W one: the Pi 5 won't boot from USB with a 3 A supply. Use the official supply, or add usb_max_current_enable=1 to /boot/firmware/config.txt if you know your supply and SSD are fine with it.

findmnt / then says /dev/nvme0n1p2 (NVMe) or /dev/sda2 (USB) instead of /dev/mmcblk0p2 (the card). If a USB SSD doesn't start, try the other blue port or another USB case; some cheap adapters misbehave.

Make it last#

A few small settings mean far fewer writes. They help on an SSD and matter most on a microSD card:

• Keep the system log small: create /etc/systemd/journald.conf.d/iskra.conf with
  ini

  [Journal]
  SystemMaxUse=50M
  

  and run sudo systemctl restart systemd-journald. On a card you can use Storage=volatile instead, which keeps the log in memory only (it's gone after a restart, along with any clues about what went wrong).
• noatime: the disk doesn't note every time a file is read. Raspberry Pi OS already does this; findmnt -no OPTIONS / should show noatime. If not, add noatime to the options of / in /etc/fstab.
• Swap: leave Raspberry Pi OS's own setting alone (current versions mostly swap into compressed memory). Iskra needs about 1 GB, so a Pi with 2 GB or more rarely swaps. Don't add a big swap file on a card.
• Keep the Iskra folder on the system disk (the card or the SSD), as in the steps below. Don't run it from a USB stick or a network share; those are for backup copies.

2. Install#

Download the package for your box from the releases page and unpack it into a folder of its own, then start it with a folder for the server (it's made on the first run):

# Linux and Raspberry Pi
mkdir -p ~/iskra && tar -xzf iskra-server-*-linux-*.tar.gz -C ~/iskra
~/iskra/iskra-server ~/iskra/world

# Windows: unpack the zip into, say, C:\Iskra, then in a terminal:
C:\Iskra\iskra-server.exe C:\Iskra\world

The first time, the server prints a one-time owner link (also saved in world/owner-invite.txt). Open it in the Iskra app, or at app.iskra.foo, and you're the owner. Then press Ctrl+C to stop it: the next step makes it start on its own.

Windows asks once whether Iskra may use the network: choose Allow (private networks are enough at home).

With a screen and a desktop app instead? On a Windows, Mac or Linux PC you can also use the Iskra desktop app: Create a server, then tick Keep my server running. Iskra then starts with the computer, hidden in the tray, and updates together with the app. The rest of this guide is about the standalone server, which needs no screen.

3. Start with the computer#

Linux and Raspberry Pi: a system service (recommended)#

A system service starts at boot, before anyone logs in, and is what automatic updates need. Install Iskra in /opt/iskra for its own user:

sudo useradd --system --create-home --home-dir /opt/iskra iskra
sudo tar -xzf iskra-server-*-linux-*.tar.gz -C /opt/iskra
sudo mv ~/iskra/world /opt/iskra/world        # if you already made the server in step 2
sudo chown -R iskra:iskra /opt/iskra

Then create /etc/systemd/system/iskra.service with the unit from Hosting reference (it's the same at home and on a rented server) and turn it on:

sudo systemctl enable --now iskra
sudo journalctl -u iskra -f          # its output; shows the owner link on a new server

Or: one command, as your own user (Windows, macOS, Linux)#

iskra-server install-autostart ~/iskra/world      # Windows: iskra-server.exe install-autostart C:\Iskra\world

It prints how to start it right away. What it sets up:

• Windows: a scheduled task that starts when you log in, without a window. Run the command from an administrator terminal and it starts with the computer instead, before anyone logs in (still as you, never with administrator rights).
• Linux: a systemd user service that starts when you log in. loginctl enable-linger $USER makes it start at boot. Automatic updates need the system service above.
• macOS: a launchd agent that starts when you log in.

iskra-server remove-autostart <folder> undoes it.

4. Let friends in from the internet#

At home, friends on your own network can join right away. For everyone else:

The easy way: Let friends anywhere join#

As the owner, open Server settings → Internet access in the app and turn on Let friends anywhere join. Iskra asks your router to open the ports (UPnP or NAT-PMP), gives the server a free address like 203-0-113-7.sslip.io, gets an HTTPS certificate for it, and keeps all of that up to date. A checklist shows how each step went. Details: Hosting reference.

Give the box a fixed address on your network (in the router: "DHCP reservation" or "static lease" for the box), so the router keeps sending friends to the right computer.

If the router won't open ports#

Many routers have UPnP turned off. Either turn it on in the router's settings, or forward these ports to the box by hand (Server settings → Internet access → Forward the ports yourself lists them with your addresses, and can write a question for an AI assistant with your router's model filled in):

If the box has its own firewall (ufw on Ubuntu, firewalld on Fedora), allow 47070/tcp, 7881/tcp and 7882/udp there too.

If your connection is shared (CGNAT)#

Some providers share one public address between many homes (carrier-grade NAT, common on mobile broadband and some fiber). Then no port forwarding can work, and What Iskra found out in Server settings → Internet access says so. Your options:

1. Ask your provider for a public IPv4 address. Often free and done once; then everything above works.
2. Tailscale (free for small groups): you and each friend install it once, and friends reach your box as if it were on their own network. Iskra notices Tailscale on the box by itself and offers Invite friends → Over Tailscale. Friends join with the Iskra app (browsers need HTTPS, which this route doesn't have).
3. Connect without port forwarding (experimental): turn it on in Server settings → Internet access. It works with the desktop app's Keep my server running and with the standalone server, Raspberry Pi included (the iskra-p2p program in the download does it; see Hosting reference).
4. Rent a small server instead. If home hosting doesn't work out, the app can set one up for about $6 a month (Rent a small server), and your server can move there with everyone and everything in it.

5. Updates#

As the owner, open Server settings → Server updates:

• Install automatically (Linux with the system service from step 3): the server checks every 6 hours, downloads new versions from GitHub, checks them (checksums and the signed build attestation), installs them at night once nobody is in voice, and puts the old version back by itself if the new one doesn't start.
• Tell me (the default, and everywhere else): you get a notice in the app. To update by hand, stop the server, unpack the new package over the old files (the world folder isn't in the package and stays as it is), and start it again.

The operating system needs updates too. On Ubuntu and Debian, security updates install themselves with unattended-upgrades (sudo apt install unattended-upgrades); on Raspberry Pi OS, run sudo apt update && sudo apt full-upgrade now and then, or install unattended-upgrades too.

6. Backups#

• Daily backups are on by default: every day the server keeps a copy of its database, settings and keys in world/backups/ (the last 7). They help with mistakes, not with a dead disk.

• Copy them to another disk, encrypted: in Server settings → Backup & move → Also copy them to, enter a folder on a USB stick, a second disk or a network share mounted on the box (another computer's shared folder works too), such as /mnt/usb/iskra, and choose a passphrase. After each daily backup the server encrypts it with that passphrase (the same format as a downloaded backup) and writes it there as auto-YYYY-MM-DD.iskrabackup, keeping the same number of days. Keep the passphrase somewhere safe, like a password manager: you need it to restore a copy. The folder must exist and the server's user must be able to write to it (sudo mkdir -p /mnt/usb/iskra && sudo chown iskra:iskra /mnt/usb/iskra); if the stick isn't mounted, Server settings says so and the next try is an hour later. For a stick that's always plugged in, mount it at boot with a line in /etc/fstab using its UUID (from lsblk -f) and nofail, so the Pi still starts without it. Details: Hosting reference.

• Download a backup now and then: Server settings → Backup & move → Make backup gives you one encrypted file with everything (keep the passphrase somewhere else). Put it on another computer or a USB stick.

• From a script, for example a weekly job that writes to a NAS. It works while the server runs; run it as the server's user (the folder is readable by that user only), into a folder that user can write to:

  shell

  echo "$PASSPHRASE" | sudo -u iskra /opt/iskra/iskra-server backup /opt/iskra/world /mnt/nas/iskra/iskra-$(date +%F).iskrabackup --passphrase-stdin
  

If the card or disk dies: get a new card (or SSD), install the system and Iskra again (1, 2, 3), then restore the newest backup into an empty world folder instead of starting a new server, before you start the service:

sudo -u iskra /opt/iskra/iskra-server restore /mnt/usb/iskra/auto-2026-10-14.iskrabackup /opt/iskra/world   # asks for the passphrase

A downloaded .iskrabackup file restores the same way. Everything comes back, with the server's own key, so friends' apps simply reconnect: no new invites. See Restoring; to hand the server to another computer, Move this server.

7. Power use#

An always-on box runs about 8,760 hours a year, so every watt is about 9 kWh a year.

Iskra itself uses next to nothing while nobody talks; voice calls add a little.

• Keep it awake, let the screen sleep. Turn off sleep and hibernation (Windows: Settings → System → Power; macOS: System Settings → Energy, "Prevent automatic sleeping"; Linux desktops: the power settings). Turning off the display is fine.
• No screen at all? On Linux, a server or "Lite" install without a desktop saves memory and power.
• Back after a power cut: in the PC's BIOS/UEFI settings, set "Restore on AC power loss" (or similar) to Power On. A Raspberry Pi starts by itself when power comes back. The service from step 3 starts Iskra.
• Laptops: close the lid with "do nothing" as the lid action, and keep it plugged in. Many laptops can limit charging to about 80 %, which is kinder to the battery.
• Old desktops use the most. If you have one, a mini PC or a Pi usually pays for itself in electricity within a few years.
• Use a wired connection for voice, and a small UPS if power cuts are common where you live.

Help#

• Something's off? Server settings → Internet access explains what it found. The server's log is in logs/ in the server folder (one file per day), and also in journalctl -u iskra (system service) or journalctl --user -u iskra-… (user service). The desktop app keeps its own log too, in logs/ in its data folder (Windows: %APPDATA%\iskra-desktop\logs; see Hosting reference, Logs).
• The full reference, every setting and every file: Hosting reference.