Installing on Linux

Download the package matching your distro from the releases page. All packages are 64-bit (x86_64) only (file names below are for release 1.3.17).

Debian, Ubuntu, Mint, Pop!_OS

sudo apt install ./lmc_1.3.17_amd64.deb

Fedora, RHEL, CentOS

sudo dnf install ./lmc-1.3.17-1.x86_64.rpm

openSUSE

sudo zypper install ./lmc-1.3.17-1.x86_64.rpm

Arch, Manjaro

sudo pacman -U ./lmc-1.3.17-1-x86_64.pkg.tar.zst

Dependencies (system Qt 6, OpenSSL) resolve automatically through your package manager — no manual Qt install, no building from source (see Building on Linux only if you compile it yourself). Emoji in chat render with the OS color emoji font; the packages recommend it so it is normally installed automatically (fonts-noto-color-emoji on Debian/Ubuntu, google-noto-color-emoji-fonts on Fedora, noto-fonts-emoji on Arch). The app runs without it, but emoji show up as empty boxes until you install the font.

After install, launch LAN Messenger from the applications menu (or run lmc in a terminal). The menu entry, icons, and the /usr/bin/lmc launcher are part of the package.

Firewall

Unlike the Windows firewall, ufw and firewalld grant access by port, not by application — so LAN Messenger needs its ports opened explicitly:

Direction	Port	Used for
Inbound UDP	50000	Peer discovery (multicast group 239.255.100.100 plus directed broadcast)
Inbound TCP	50000 by default	Messages and file transfers (or the TCP port set in Preferences → Network → TCP Port)

To receive messages and files, the machine’s inbound TCP port must be reachable; sending needs the peer’s inbound TCP port open. So open the ports on each machine:

# Debian, Ubuntu (ufw)
sudo ufw allow 50000/udp
sudo ufw allow 50000/tcp

# Fedora, RHEL, openSUSE (firewalld)
sudo firewall-cmd --permanent --add-port=50000/udp
sudo firewall-cmd --permanent --add-port=50000/tcp
sudo firewall-cmd --reload

VPN connections and Wi-Fi client isolation also block discovery: machines must reach each other directly on the local network, not only the internet. Check with:

ss -ulnp | grep 50000          # UDP discovery listener
ss -tlnp | grep lan-messenger  # TCP listener

For machines on different subnets, add the remote broadcast addresses under Preferences → Network → Broadcast.

Update and uninstall

Install the new package over the old one with the same command as above; settings and history are kept. To remove:

sudo apt remove lmc          # Debian/Ubuntu
sudo dnf remove lmc          # Fedora/RHEL/CentOS
sudo zypper remove lmc       # openSUSE
sudo pacman -R lmc           # Arch

Uninstall keeps your personal data. To wipe it too, delete ~/.config/lmc/ (settings) and ~/.local/share/lmc/ (history, avatars).

If it still doesn’t start

Run lmc in a terminal and note the output. Open an issue with your distro and version, your desktop (X11 or Wayland), the exact package file name, and the terminal output.