62 lines
2.1 KiB
Markdown
62 lines
2.1 KiB
Markdown
 
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# Running tsunagi on Linux
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This archive holds a **static** `tsunagi` binary (musl), so it runs on any
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distribution — Arch, Alpine, NixOS, old glibc systems — with no shared-library
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dependencies. Alongside it are a systemd unit and an installer.
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Creating the TUN interface needs `CAP_NET_ADMIN`, and configuring
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systemd-resolved is decided by polkit (by user id, not capability). There are
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three ways to satisfy that; pick one.
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## Quick install — systemd service as root
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```sh
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sudo ./install.sh
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sudo systemctl enable --now tsunagi
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```
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The service runs the agent as root, so the interface, low ports and the
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resolver all just work (root is not subject to polkit). Control it **as root**,
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so the client resolves the same state directory the daemon uses:
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```sh
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sudo tsunagi status
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sudo tsunagi join <network-name> <tsn1…secret>
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```
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## As your own user — one capability, no root at runtime
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```sh
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sudo install -m 0755 tsunagi /usr/local/bin/tsunagi
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sudo setcap cap_net_admin,cap_net_bind_service+p /usr/local/bin/tsunagi
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tsunagi up
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```
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Nothing is left behind and nothing runs as root. The capability is lost on every
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rebuild or copy of the binary, so re-run `setcap` after replacing it. For the
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local DNS resolver, run `tsunagi dns` once: it prints the exact polkit rule that
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lets your user configure systemd-resolved, ready to paste.
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## Without touching the OS
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```sh
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tsunagi up --no-tun
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```
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Tunnels form and handshake between agents, but no interface, address or route is
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created, so traffic never reaches the operating system. Needs no privileges.
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## What the agent installs
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Everything is tagged to its own interface, computed from local state, and
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reversible — removed when a network leaves, broadcast is turned off, or the
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agent stops:
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- a TUN interface configured over netlink (addresses, MTU, up);
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- while broadcast is on, a `255.255.255.255` route through the interface and an
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inbound-UDP firewall allowance from the overlay range (`iptables`, tagged);
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- the systemd-resolved setting that sends the overlay zones' questions to the
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local resolver.
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Nothing taken from a remote peer ever becomes a path, a command argument or an
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OS setting.
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