Configuration

Connecto stores configuration in platform-specific locations.

Config file location

Find your config path:

connecto config path

Config file format

{
  "subnets": [
    "10.0.2.0/24",
    "192.168.100.0/24"
  ],
  "default_key": "/Users/john/.ssh/id_ed25519"
}

Fields

Device cache

connecto scan caches its results so connecto pair <number> can resolve device numbers. The cache lives in the per-user cache directory:

SSH Configuration

Connecto modifies ~/.ssh/config when pairing or syncing. Each paired host gets a four-line block preceded by a marker comment:

# Added by connecto
Host mydesktop
    HostName 192.168.1.55
    User john
    IdentityFile /home/user/.ssh/connecto_mydesktop

Entry fields

The # Added by connecto marker is how Connecto tells its own entries apart from yours: hosts, unpair, update-ip, and export only ever read or modify marked blocks. Hand-written host blocks are never listed, rewritten, or removed — even if they share an alias with a managed entry. Config writes are atomic, so an interrupted write cannot truncate the file.

SSH Keys

Keys are stored in the SSH directory:

Key files

For each paired host:

• ~/.ssh/connecto_<device> - Private key (mode 600)
• ~/.ssh/connecto_<device>.pub - Public key

Keys generated by connecto sync use the connecto_sync_ prefix. <device> is the device name sanitized to a lowercase alias (e.g. My Desktop → my-desktop). When a default key is configured (connecto config set-default-key) or --key is used, no new files are created and the config entry points at the existing key.

Key type

Connecto generates Ed25519 keys by default:

• Modern elliptic curve cryptography
• 128-bit security level
• Small key size (compact authorized_keys)
• Fast generation and authentication

RSA-4096 is available via --rsa.

Home directory resolution

Connecto resolves your home directory (for ~/.ssh and friends) through one shared strategy: the platform user-directories API first, then the HOME / USERPROFILE environment variables as a fallback. The CLI and core library always agree on where ~/.ssh is.

Ports

authorized_keys format

When accepting a pairing, Connecto appends the received public key to ~/.ssh/authorized_keys exactly as sent:

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIG... user@laptop

The trailing comment is the key’s own comment — user@hostname by default, or whatever was passed via --comment. Duplicate keys are not added twice, and the file is rewritten atomically. Use connecto keys list / connecto keys remove to manage it.