20122013
Ericsson AB. All Rights Reserved.
The contents of this file are subject to the Erlang Public License,
Version 1.1, (the "License"); you may not use this file except in
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
Software distributed under the License is distributed on an "AS IS"
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the License for the specific language governing rights and limitations
under the License.
SSH
ssh_app.xml
SSH
The ssh application implements the Secure Shell (SSH) protocol and
provides an SSH File Transfer Protocol (SFTP) client and server.
The ssh application is an implementation of the SSH protocol in Erlang.
ssh offers API functions to write customized SSH clients and servers as well as
making the Erlang shell available over SSH. An SFTP client, ssh_sftp, and server,
ssh_sftpd, are also included.
DEPENDENCIES
The ssh application uses the applications public_key and
crypto to handle public keys and encryption. Hence, these
applications must be loaded for the ssh application to work. In
an embedded environment this means that they must be started with
application:start/[1,2] before the ssh application is started.
CONFIGURATION
The ssh application does not have an application-
specific configuration file, as described in application(3).
However, by default it use the following configuration files
from OpenSSH:
- known_hosts
- authorized_keys
- authorized_keys2
- id_dsa
- id_rsa
- ssh_host_dsa_key
- ssh_host_rsa_key
By default, ssh looks for id_dsa, id_rsa,
known_hosts, and authorized_keys in ~/.ssh,
and for the host key files in /etc/ssh. These locations can be changed
by the options user_dir and system_dir.
Public key handling can also be customized through a callback module that
implements the behaviors
ssh_client_key_api and
ssh_server_key_api.
Public Keys
id_dsa and id_rsa are the users private key files.
Notice that the public key is part of the private key so the ssh
application does not use the id_<*>.pub files. These are
for the user's convenience when it is needed to convey the user's
public key.
Known Hosts
The known_hosts file contains a list of approved servers and
their public keys. Once a server is listed, it can be verified
without user interaction.
Authorized Keys
The authorized_key file keeps track of the user's authorized
public keys. The most common use of this file is to let users
log in without entering their password, which is supported by the
Erlang ssh daemon.
Host Keys
RSA and DSA host keys are supported and are
expected to be found in files named ssh_host_rsa_key and
ssh_host_dsa_key.
ERROR LOGGER AND EVENT HANDLERS
The ssh application uses the default OTP error logger to log unexpected errors or print information about special events.