Sep 06, 2017 Marcelo Filho added a comment - 2018-04-03 18:30 Rashed Amiri actually there is no standard way to workaround this once looks very random. The source of the problem is that somehow the XML of the credentials is changed and the XML format is broken but even after many plugins installation and uninstallation the source plugin or cause was not found. Automate config backups so you can quickly roll back a blown configuration or provision a replacement device. Continuously audit configs and get alerted if a device is out of compliance, then be able to remediate vulnerabilities rapidly through bulk config deployment.
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This page is about OpenSSH client configuration. For OpenSSH server configuration, see.
For Tectia SSH configuration, see. For configuring passwordless public key authentication, see.The program on a host receives its configuration from either the command line or from configuration files /.ssh/config and /etc/ssh/sshconfig.options take precedence over configuration files. The user-specific configuration file /.ssh/config is used next. Finally, the global /etc/ssh/sshconfig file is used.
The first obtained value for each configuration parameter will be used. Contents Commonly used configuration optionsThere are many configuration options available.
In practice, only a few of them are ever changed, and user-specific configuration files are rarely used. In most cases, just /etc/ssh/sshconfig is edited. Enabling X11 forwarding and agent forwardingDevelopers, students, and researchers often want to enable X11 forwarding and SSH agent forwarding. These allow running graphical applications remotely and eliminate the need for typing a password whenever moving from one server to another, respectively. Setting these options in /etc/ssh/sshconfig makes life easier for end users, saves overhead, and reduces support load. However, they increase the risk of an attack spreading from a compromised server to a user's desktop, so the most security-critical environments may want to leave them disabled. There is generally no reason to enable them on production servers in enterprises.
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ForwardAgent yesForwardX11 yes Port forwardingLocal and remote port forwarding can be used for tunneling applications, accessing intranet web services from home, tunneling database access, and many other purposes. For instructions on configuring port forwarding, see the. Note, however, that port forwarding can also be used to tunnel traffic from the external Internet into a corporate intranet. Employees sometimes do this to be able to work from home even when company policy does not permit it. Hackers use it to leave permanent backdoor. See the page on for more information. Configuring public key authenticationPublic authentication is used for passwordless logins between systems.
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It is often used for automated processes, such as backups, configuration management, and file transfers. It is also used by sophisticated end users and system administrators for single sign-on. See the for configuring it.When a user has created more than one for authentication, the -i command line option may be helpful for specifying which key to use. In the client configuration file, this can be specified using the IdentityFile options.
Certificate-based authenticationOpenSSH certificates can be used for authentication either using or by specifying the CertificateFile option in the client configuration file. See for more information. Format of SSH client config file sshconfigThe sshconfig client configuration file has the following format. Both the global /etc/ssh/sshconfig and per-user /ssh/config have the same format.Empty lines and lines starting with '#' are comments.Each line begins with a keyword, followed by argument(s).Configuration options may be separated by whitespace or optional whitespace and exactly one =.Arguments may be enclosed in double quotes (') in order to specify arguments that contain spaces.Listing of client configuration optionsThe following keywords can be used in SSH client configuration files.
Keywords are case-insensitive and arguments are case-sensitive. Any algorithm or method names that include an at sign (@) are for experimental use only and not recommended for production.HostRestricts the following declarations to be only for those hosts that match one of the patterns given after the keyword.
The pattern is matched against the host name given on the command line.MatchRestricts the following declarations to apply only for hosts that match the specified criteria. For detailed information, see.AddressFamilySpecifies which address family to use when connecting. Valid arguments are: any, inet, inet6.BatchModeIf set to yes, passphrase/password querying will be disabled. This is useful for running the ssh client from shell script that do not have an interactive user, and prevents accidentally blocking on a password prompt.BindAddressSpecifies to use the specified address on the local machine as the source address of the connection.ChallengeResponseAuthenticationSpecifies whether to use challenge-response authentication.
This is mostly a legacy method and has been replaced by KbdInteractiveAuthentication.CheckHostIPDirects ssh to additionally check the host IP address in the knownhosts file.CipherSpecifies the cipher to use for encrypting the session in protocol version 1. Note that use of protocol 1 is not recommended.CiphersSpecifies the ciphers allowed for protocol version 2 in order of preference. Multiple ciphers must be comma-separated. The ssh -Q cipher command can be used to query supported ciphers. The following list is supported in 6.7: 3des-cbcblowfish-cbccast128-cbcarcfourarcfour128arcfour256aes128-cbcaes192-cbcaes256-cbcrijndael-cbc@lysator.liu.seaes128-ctraes192-ctraes256-ctraes128-gcm@[email protected]@openssh.comClearAllForwardingsSpecifies that all local, remote, and dynamic port forwardings specified in the configuration files or on the command line be cleared.CompressionSpecifies whether to use compression.
The /etc/ssh/sshconfig file is the system-wide configuration file for OpenSSH which allows you to set options that modify the operation of the client programs. The filecontains keyword-value pairs, one per line, with keywords being case insensitive. Host.The option Host restricts all forwarded declarations and options in the configuration file to be only for those hosts that match one of the patterns given after the keyword. Thepattern. means for all hosts up to the next Host keyword.
With this option you can set different declarations for different hosts in the same sshconfig file.ForwardAgent noThe option ForwardAgent specifies which connection authentication agent if any should be forwarded to the remote machine.ForwardX11 noThe option ForwardX11 is for people that use the Xwindow GUI and want to automatically redirect X11 sessions to the remote machine. Since we setup a serverand don't have GUI installed on it, we can safely turn this option off.RhostsAuthentication noThe option RhostsAuthentication specifies whether we can try to use rhosts based authentication.
Because rhosts authentication is insecure you shouldn't use this option.RhostsRSAAuthentication noThe option RhostsRSAAuthentication specifies whether or not to try rhosts authentication in concert with RSA host authentication.RSAAuthentication yesThe option RSAAuthentication specifies whether to try RSA authentication. This option must be set to yes for better security on your sessions. RSA uses public and private keys pair created withthe ssh-keygen1utility for authentication purposes.PasswordAuthentication yesThe option PasswordAuthentication specifies whether we should use password-based authentication.
For strong security, this option must always be set to yes.FallBackToRsh noThe option FallBackToRsh specifies that if a connection with ssh daemon fails rsh should automatically be used instead. Recalling that rsh service is insecure, this option must always be set to no.UseRsh noThe option UseRsh specifies that rlogin/rsh services should be used on this host. As with the FallBackToRsh option, it must be set to no for obvious reasons.BatchMode noThe option BatchMode specifies whether a username and password querying on connect will be disabled.
This option is useful when you create scripts and dont want to supply the password. Scriptsthat use the scp command to make backups over the network.CheckHostIP yesThe option CheckHostIP specifies whether or not ssh will additionally check the host IP address that connect to the server to detect DNS spoofing. It's recommended that you set this optionto yes.StrictHostKeyChecking noThe option StrictHostKeyChecking specifies whether or not ssh will automatically add new host keys to the $ HOME/.ssh/knownhosts file, or never automatically add newhost keys to the host file. This option, when set to yes, provides maximum protection against Trojan horse attacks.
One interesting procedure with this option is to set it to noat the beginning, allow ssh to add automatically all common hosts to the host file as they are connected to, and then return to set it to yes to take advantage of this feature.IdentityFile /.ssh/identityThe option IdentityFile specifies an alternate RSA authentication identity file to read. Also, multiple identity files may be specified in the configuration file sshconfig.Port 22The option Port specifies on which port number ssh connects to on the remote host. The default port is 22.Cipher blowfishThe option Cipher specifies what cipher should be used for encrypting sessios. The blowfish use 64-bit blocks and keys of up to 448 bits.EscapeChar The option EscapeChar specifies the session escape character for suspension.
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