View Source ssh_file (ssh v5.2)
Default callback module for the client's and server's database operations in the ssh application
This module is the default callback handler for the client's and the server's user and host "database" operations. All data, for instance key pairs, are stored in files in the normal file system. This page documents the files, where they are stored and configuration options for this callback module.
The intention is to be compatible with the OpenSSH storage in files. Therefore it mimics directories and filenames of OpenSSH.
Ssh_file implements the ssh_server_key_api and the ssh_client_key_api.
This enables the user to make an own interface using for example a database
handler.
Such another callback module could be used by setting the option
key_cb when starting a client or a server
(with for example ssh:connect, ssh:daemon
of ssh:shell ).
Note
The functions are Callbacks for the SSH app. They are not intended to be called from the user's code!
Files, directories and who uses them
Daemons
Daemons uses all files stored in the SYSDIR directory.
Optionally, in case of publickey authorization, one or more of the remote
user's public keys in the USERDIR directory are used.
See the files USERDIR/authorized_keys and
USERDIR/authorized_keys2.
Clients
Clients uses all files stored in the USERDIR directory.
Directory contents
LOCALUSER
The user name of the OS process running the Erlang virtual machine (emulator).SYSDIR
This is the directory holding the server's files:-
ssh_host_dsa_key- private dss host key (optional) ssh_host_rsa_key- private rsa host key (optional)ssh_host_ecdsa_key- private ecdsa host key (optional)ssh_host_ed25519_key- private eddsa host key for curve 25519 (optional)ssh_host_ed448_key- private eddsa host key for curve 448 (optional)
The key files could be generated with OpenSSH's ssh-keygen command.
At least one host key must be defined. The default value of SYSDIR is
/etc/ssh.For security reasons, this directory is normally accessible only to the root user.
To change the SYSDIR, see the system_dir option.
-
USERDIR
This is the directory holding the files:authorized_keysand, as second alternativeauthorized_keys2- the user's public keys are stored concatenated in one of those files.It is composed of lines as for OpenSSH:
(options)? keytype base64-encoded-key commentwhere
options :: option(,option)* option :: % All options are skipped keytype :: 'ssh-dsa' | 'ssh-rsa' | 'ssh-ecdsa-nistp256' | 'ssh-ecdsa-nistp384' | 'ssh-ecdsa-nistp521' | 'ssh-ed25519' | 'ssh-ed448' base64-encoded-key :: % The user's public key comment :: % Comments are skippedknown_hosts- host keys from hosts visited concatenated. The file is created and used by the client.It is composed of lines as for OpenSSH:
(option)? pattern(,pattern)* keytype key (comment)?where
option :: '@revoked' pattern :: host | '[' host ']:' port host :: ip-address | hostname | '*' port :: portnumber | '*' keytype :: 'ssh-dsa' | 'ssh-rsa' | 'ssh-ecdsa-nistp256' | 'ssh-ecdsa-nistp384' | 'ssh-ecdsa-nistp521' | 'ssh-ed25519' | 'ssh-ed448' key :: % encoded key from eg ssh_host_*.pubid_rsa- private rsa user key (optional)id_ecdsa- private ecdsa user key (optional)id_ed25519- private eddsa user key for curve 25519 (optional)id_ed448- private eddsa user key for curve 448 (optional)
The key files could be generated with OpenSSH's ssh-keygen command.
The default value of USERDIR is
/home/LOCALUSER/.ssh.To change the USERDIR, see the user_dir option
Summary
Functions
Types and description
Decodes an SSH file-binary.
Encodes a list of SSH file entries (public keys and attributes) to a binary.
Fetches the public key from a private key.
Types and description
Types and description
Types and description
Types and description
Types: Options for the default ssh_file callback module
Functions
-spec add_host_key(Host, Port, Key, Options) -> Result when Host :: inet:ip_address() | inet:hostname() | [inet:ip_address() | inet:hostname()], Port :: inet:port_number(), Key :: public_key:public_key(), Options :: ssh_client_key_api:client_key_cb_options(none()), Result :: ok | {error, term()}.
Types and description
See the api description in ssh_client_key_api, Module:add_host_key/4.
Note that the alternative, the old
Module:add_host_key/3 is no longer
supported by ssh_file.
Option
File
-spec decode(SshBin, Type) -> Decoded | {error, term()} when SshBin :: binary(), Type :: ssh2_pubkey | public_key | openssh_key | rfc4716_key | openssh_key_v1 | known_hosts | auth_keys, Decoded :: Decoded_ssh2_pubkey | Decoded_public | Decoded_openssh | Decoded_rfc4716 | Decoded_openssh_key_v1 | Decoded_known_hosts | Decoded_auth_keys, Decoded_ssh2_pubkey :: public_key:public_key(), Decoded_public :: Decoded_rfc4716 | Decoded_openssh_key_v1 | Decoded_openssh, Decoded_openssh :: [{public_key:public_key(), [{comment, string()}]}], Decoded_rfc4716 :: [{key(), [{headers, Attrs}]}], Decoded_openssh_key_v1 :: experimental_openssh_key_v1(), Decoded_known_hosts :: [{public_key:public_key(), [{comment, string()} | {hostnames, [string()]}]}], Decoded_auth_keys :: [{public_key:public_key(), [{comment, string()} | {options, [string()]}]}], Attrs :: {Key :: string(), Value :: string()}.
Decodes an SSH file-binary.
If Type is public_key the binary can be either an RFC4716 public key or an
OpenSSH public key.
Note
The implementation of the
openssh_key_v1format is still experimental.
-spec encode(InData, Type) -> binary() | {error, term()} when Type :: ssh2_pubkey | openssh_key | rfc4716_key | openssh_key_v1 | known_hosts | auth_keys, InData :: InData_ssh2_pubkey | InData_openssh | InData_rfc4716 | InData_openssh_key_v1 | InData_known_hosts | InData_auth_keys, InData_ssh2_pubkey :: public_key:public_key(), InData_openssh :: [{public_key:public_key(), [{comment, string()}]}], InData_rfc4716 :: [{key(), [{headers, Attrs}]}], InData_openssh_key_v1 :: experimental_openssh_key_v1(), InData_known_hosts :: [{public_key:public_key(), [{comment, string()} | {hostnames, [string()]}]}], InData_auth_keys :: [{public_key:public_key(), [{comment, string()} | {options, [string()]}]}], Attrs :: {Key :: string(), Value :: string()}.
Encodes a list of SSH file entries (public keys and attributes) to a binary.
Note
The implementation of the
openssh_key_v1format is still experimental.
-spec extract_public_key(PrivKey) -> PubKey when PrivKey :: public_key:private_key(), PubKey :: public_key:public_key().
Fetches the public key from a private key.
-spec host_key(Algorithm, Options) -> Result when Algorithm :: ssh:pubkey_alg(), Result :: {ok, public_key:private_key()} | {error, term()}, Options :: ssh_server_key_api:daemon_key_cb_options(none()).
Types and description
See the api description in ssh_server_key_api, Module:host_key/2.
Options
Files
-spec is_auth_key(Key, User, Options) -> boolean() when Key :: public_key:public_key(), User :: string(), Options :: ssh_server_key_api:daemon_key_cb_options(optimize_key_lookup()).
Types and description
See the api description in ssh_server_key_api: Module:is_auth_key/3.
Options
Files
This functions discards all options in the beginning of the lines of thoose files when reading them.
-spec is_host_key(Key, Host, Port, Algorithm, Options) -> Result when Key :: public_key:public_key(), Host :: inet:ip_address() | inet:hostname() | [inet:ip_address() | inet:hostname()], Port :: inet:port_number(), Algorithm :: ssh:pubkey_alg(), Options :: ssh_client_key_api:client_key_cb_options(optimize_key_lookup()), Result :: boolean() | {error, term()}.
Types and description
See the api description in ssh_client_key_api, Module:is_host_key/5.
Note that the alternative, the old
Module:is_host_key/4 is no longer
supported by ssh_file.
Option
File
-spec user_key(Algorithm, Options) -> Result when Algorithm :: ssh:pubkey_alg(), Result :: {ok, public_key:private_key()} | {error, string()}, Options :: ssh_client_key_api:client_key_cb_options(none()).
Types and description
See the api description in ssh_client_key_api, Module:user_key/2.
Options
Note that EdDSA passhrases (Curves 25519 and 448) are not implemented.
Files