ssh-broker-g3 — SSH Connection Broker - Generation 3
The information presented here is also valid for the ssh-socks-proxy command. Running ssh-socks-proxy, will actually run ssh-broker-g3 in the SOCKS Proxy mode, using the
ssh-broker-g3 is a component of SSH Tectia client tools for z/OS. It handles all cryptographic operations and authentication-related tasks for the SSH Tectia client programs sshg3, scpg3, and sftpg3.
ssh-broker-g3 uses the Secure Shell version 2 protocol to communicate with a Secure Shell server.
You can start the Connection Broker manually by using the ssh-broker-g3 command. This starts ssh-broker-g3 in the background and all following uses of sshg3, sftpg3, or scpg3 will connect via this instance of the Connection Broker instead of starting a new Broker session.
If a command-line client (sshg3, sftpg3, or scpg3) is started when the Connection Broker is not running in the background, the client starts the Broker in run-by-need mode. In this mode, ssh-broker-g3 will exit after the last client has disconnected.
If there is an ssh-broker-g3 process running in the run-by-need mode, and the Connection Broker is started from the command line, the new ssh-broker-g3 process sends a message to the old ssh-broker-g3 process to change from the run-by-need mode to the background mode, keeping the Broker running after the clients disconnect.
The Connection Broker operates automatically as an authentication agent, storing user's public keys and forwarding the authentication over Secure Shell connections. Key pairs can be created with
The public key pairs used for user authentication are by default stored in the
$HOME/.ssh2 directory. See the section called “Files” for more information.
The Connection Broker automatically maintains and checks a database containing the public host keys used for authenticating Secure Shell servers. When logging in to a server host for the first time, the host's public key is stored in the user's
$HOME/.ssh2/hostkeys directory. See the section called “Files” for more information.
The most important options of ssh-broker-g3 are the following:
Reads the Connection Broker configuration file from
FILEinstead of the default location.
Sets the debug level string to
Dumps debug messages to
Make the currently running Connection Broker exit. This will terminate all connections.
Re-reads the configuration file (
ssh-broker-config.xml) and takes it into use.
Displays program version and exits.
Displays a short summary of command-line options and exits.
ssh-broker-g3 uses the following files:
This is the user-specific configuration file used by ssh-broker-g3 (and sshg3, scpg3, and sftpg3). The format of this file is described in ssh-broker-config(5). This file does not usually contain any sensitive information, but the recommended permissions are read/write for the user, and not accessible for others.
This file is used for seeding the random number generator. It contains sensitive data and its permissions should be read/write for the user and not accessible for others. This file is created the first time the program is run and it is updated automatically. You should never need to read or modify this file.
This file contains information on public keys and certificates used for user authentication when contacting remote hosts.
With SSH Tectia Client G3, using the
identificationfile is not necessary if all user keys are stored in the default directory and you allow all of them to be used for public-key and/or certificate authentication. If the
identificationfile does not exist, the Connection Broker attempts to use each key found in the
$HOME/.ssh2directory. If the
identificationfile exists, the keys listed in it are attempted first.
The identification file contains a list of private key filenames each preceded by the keyword
CertKey). An example file is shown below:
This directs the Connection Broker to use
$HOME/.ssh2/mykeywhen attempting login using public-key authentication.
The files are by default assumed to be in the
$HOME/.ssh2directory, but also a path to the key file can be given. The path can be absolute or relative to the
$HOME/.ssh2directory. If there is more than one
IdKey, they are tried in the order that they appear in the identification file.
This is the user-specific directory for storing the public keys of server hosts. You are prompted to accept new or changed keys automatically when you connect to a server, unless you have set
ssh-broker-config.xmlfile. You should verify the key fingerprint before accepting new or changed keys.
When the host key is received during the first connection to a remote host (or when the host key has changed) and you choose to save the key, its filename is stored by default in hashed format. The hashed host key format is a security feature to make address harvesting on the hosts difficult.
The storage format can be controlled with the
filename-formatattribute of the
known-hostselement of the
ssh-broker-config.xmlconfiguration file. The attribute value must be
If you are adding the keys manually, the keys should be named with
<port>is the port the Secure Shell server is running on and
<host>is the hostname you use when connecting to the server (for example,
If both the hashed and clear-text format keys exist, the hashed format takes precedence.
Note that the identification is different based on the host and port the client is connecting to. For example, the short hostname
alphais considered different from the fully qualified domain name
alpha.example.com. Also a connection with an IP, for example
10.1.54.1, is considered a different host, as is a connection to the same host but different port, for example
For more information on host keys, see Server Authentication with Public Keys in File.
This is the initialization file for hashed host key names.
This is the configuration file used by ssh-broker-g3 (and sshg3, scpg3, and sftpg3) that contains the factory default settings. It is not recommended to edit the file, but you can use it to view the default settings. The format of this file is described in ssh-broker-config(5).
This is the global (system-wide) configuration file used by ssh-broker-g3 (and sshg3, scpg3, and sftpg3). The format of this file is described in ssh-broker-config(5).
If a host key is not found in the user-specific
$HOME/.ssh2/hostkeysdirectory, this is the next location to be checked for all users. Host key files are not automatically put here but they have to be updated manually by the system administrator (
root) or by using SSH Tectia Manager.
If the administrator obtains the host keys by connecting to each host, the keys will be by default in the hashed format. In this case, also the administrator's
$HOME/.ssh2/hostkeys/saltfile has to be copied to the
This is the initialization file for hashed host key names. The file has to be copied here manually by the same administrator that obtains the host keys.
This is the default file used by OpenSSH clients that contains the public key data of known server hosts. It is supported also by SSH Tectia client tools for z/OS. The location of the file must be defined in the
ssh-broker-config.xmlfile by using the
known-hostselement. See known-hosts.
The file is never automatically updated by SSH Tectia Client or ConnectSecure. New host keys are always stored in the SSH Tectia
The file contains one known host per row. The format of each row is as follows:
hostnames bits exponent modulus comment
The hostname(s) in the file must be in clear-text format. Hashed hostnames are not supported.
For more information on the format of this file, see the OpenSSH sshd(8) man page.
$HOME/.ssh2/authorized_keys(on the server host)
This directory is the default location used by SSH Tectia Server for the user public keys that are authorized for login.
On SSH Tectia Server on Windows, the default directory for user public keys is
$HOME/.ssh2/authorization(on the server host)
This is the default file used by earlier versions of SSH Tectia Server (sshd2) that lists the user public keys that are authorized for login. The file can be optionally be used with SSH Tectia Server G3 (ssh-server-g3) as well.
On SSH Tectia Server on Windows, the authorization file is by default located in
For information on the format of this file, see the ssh-server-g3(8) man page.
$HOME/.ssh/authorized_keys(on the server host)
This is the default file used by OpenSSH server (sshd) that contains the user public keys that are authorized for login.
For information on the format of this file, see the OpenSSH sshd(8) man page.