ssh_client_key_api(3erl)

💖 NAME 💖

ssh_client_key_api — -behaviour(ssh_client_key_api).

Hi bestie! This is the ssh_client_key_api page from the 3erl manual — Erlang Module Definition, and we’re about to make SSH public-key callbacks make sense. 💅

✨ DESCRIPTION ✨

Okay so this is the behavior describing the API for public key handling of an SSH client. By implementing the callbacks defined in this behavior, the public key handling of an SSH client can be customized. By default the ssh application implements this behavior with help of the standard OpenSSH files, see the ssh(7) application manual. 🫶

🧁 DATA TYPES 🧁

client_key_cb_options(T) =
    [{key_cb_private, [T]} | ssh:client_option()]

These are options provided to ssh:connect/[3,4].

The option list given in the key_cb option is available with the key key_cb_private. 🔑

🔥 EXPORTS 🔥

💅 Module:add_host_key(HostNames, PublicHostKey, ConnectOptions) -> ok | {error, Reason}

Types:

• HostNames = string() — Description of the host that owns the PublicHostKey.
• PublicHostKey = public_key:public_key() — “Of ECDSA keys, only the Normally an RSA, DSA or ECDSA public key, but handling of other public keys can be added.” (Yes, that’s literally the page’s sentence, bestie — keeping all the details, no cap.)
• ConnectOptions = client_key_cb_options()

This function is retired in favour for Module:add_host_key/4 which is the preferred API function. The calling SSH application will still try the add_host_key/3 if the call to add_host_key/4 failed.

Adds a host key to the set of trusted host keys. 💖

💅 Module:add_host_key(Host, Port, PublicHostKey, ConnectOptions) -> ok | {error, Reason}

Types:

Host = inet:ip_address() | inet:hostname() | [
inet:ip_address() | inet:hostname() ]

• Host — The host that owns the PublicHostKey. One or more IP addresses or hostnames.
• Port = inet:port_number() — The Port number of the Host.
• PublicHostKey = public_key:public_key() — “Of ECDSA keys, only the Normally an RSA, DSA or ECDSA public key, but handling of other public keys can be added.”
• ConnectOptions = client_key_cb_options()

Adds a host key to the set of trusted host keys. 💖

This function is preferred to the old Module:add_host_key/3 since it also uses the peer host port number and may return an error message.

The OTP/SSH application first calls this function in the callback module, and then the old Module:add_host_key/3 for compatibility.

💅 Module:is_host_key(Key, Host, Algorithm, ConnectOptions) -> Result

Types:

• Key = public_key:public_key() — Normally an RSA, DSA or ECDSA public key, but handling of other public keys can be added.
• Host = string() — Description of the host.
• Algorithm = ssh:pubkey_alg() — Host key algorithm.
• ConnectOptions = client_key_cb_options()
• Result = boolean()

This function is retired in favour for Module:is_host_key/5 which is the preferred API function. The calling SSH application will still try the is_host_key/4 if the call to is_host_key/5 failed.

Checks if a host key is trusted. 🔍

💅 Module:is_host_key(Key, Host, Port, Algorithm, ConnectOptions) -> Result

Types:

Host = inet:ip_address() | inet:hostname() | [
inet:ip_address() | inet:hostname() ]

• Key = public_key:public_key() — Normally an RSA, DSA or ECDSA public key, but handling of other public keys can be added.
• Host — Description of the host with one or more IP addresses or hostnames.
• Port = inet:port_number() — The Port number of the host.
• Algorithm = ssh:pubkey_alg() — Host key algorithm.
• ConnectOptions = client_key_cb_options()
• Result = boolean() | {error, Error::term()} — The exact error message depends on the actual callback module. The Error message makes the connection to fail, and is returned from e.g ssh:connect/3.

Checks if a host key is trusted. 🔍

This function is preferred to the old Module:is_host_key/4 since it also uses the peer host port number and may return an error message.

The OTP/SSH application first calls this function in the callback module, and then the old Module:is_host_key/4 for compatibility.

💅 Module:user_key(Algorithm, ConnectOptions) -> Result

Types:

• Algorithm = ssh:pubkey_alg() — Host key algorithm.
• ConnectOptions = client_key_cb_options()
• Result = {ok, public_key:private_key()} | {ok, {ssh2_pubkey, PubKeyBlob :: binary()}} | {error, term()}

Fetches the users public key matching the Algorithm. Some key callback modules may return {ssh2_pubkey, PubKeyBlob :: binary()}.

Note: The private key contains the public key.

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That’s the whole page, bestie! Source/version/page-tag sign-off: Ericsson AB · ssh 4.15.3.1 · ssh_client_key_api(3erl). Now go slay those SSH callbacks. 💅✨