Try it on one machine

Two machines on one computer, with a local test relay over plain HTTP.

cargo install iroh-relay@1.3.0 --features server --locked     # the relay program
printf 'http_bind_addr = "127.0.0.1:3340"\nenable_metrics = false\n' > ~/relay-try.toml
iroh-relay --dev -c ~/relay-try.toml &                        # test relay, plain HTTP, local only

export JAUNT_TMUX_SOCKET=jaunt-try                            # keep test sessions off your own tmux
JAUNT_HOME=~/jaunt-try/benzene jaunt relay set http://127.0.0.1:3340
JAUNT_HOME=~/jaunt-try/benzene jaunt name benzene
JAUNT_HOME=~/jaunt-try/toluene  jaunt name toluene
JAUNT_HOME=~/jaunt-try/benzene jaunt link                       # terminal 1
JAUNT_HOME=~/jaunt-try/toluene  jaunt join --relay http://127.0.0.1:3340   # terminal 2 (same JAUNT_TMUX_SOCKET)
JAUNT_HOME=~/jaunt-try/benzene jaunt toluene                       # hop; Enter ~ . to leave

JAUNT_HOME keeps everything in one directory, away from your real configuration. Clean up: JAUNT_HOME=~/jaunt-try/benzene jaunt down, the same for toluene, stop the relay (kill %1), tmux -L jaunt-try kill-server, rm -rf ~/jaunt-try ~/relay-try.toml.

The same test relay can serve two machines on one home network if it binds to the LAN address instead of 127.0.0.1 (http_bind_addr = "192.168.1.10:3340", each machine using http://192.168.1.10:3340). A plain-HTTP relay is for testing only; use an HTTPS relay (deploy/relay/) for real.