Rexec ConfigurationThe class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.
Rexec/Rshell Configuration Settings
Enables or disables secondary (stderr) stream.Some systems (most notably certain versions of Linux) do not support
the secondary stderr stream of rexec/rshell. For these systems you must
turn stderr off. Any stderr output will then be provided through
The default value for this setting is True.
|MaxStderr: Maximum storage available for the stderr buffer.This indicates the maximum amount of characters that the class will store in the stderr property. The default value is -1, which indicates there is no maximum. A value of zero (0) will disable accumulation of stderr in the stderr property, although the on_stderr event will still continue to fire.|
|MaxStdout: Maximum storage available for the stdout buffer.This indicates the maximum amount of characters that the class will store in the stdout property. The default value is -1, which indicates there is no maximum. A value of zero (0) will disable accumulation of stdout in the stdout property, although the on_stdout event will still continue to fire.|
The local port from which the remote system sends the stderr stream.The default value is 0, which instructs the class to use a
random port. Use this property with caution. If you supply a value,
it must be an available port on the system or an error will be returned.
Some systems do not support secondary stderr streams. Please refer to the EnableStderr configuration setting for more information.
IPPort Configuration Settings
|ConnectionTimeout: Sets a separate timeout value for establishing a connection.When set, this configuration setting allows you to specify a different timeout value for establishing a connection. Otherwise, the class will use timeout for establishing a connection and transmitting/receiving data.|
|FirewallAutoDetect: Tells the class whether or not to automatically detect and use firewall system settings, if available.This is the same as firewall_auto_detect. This setting is provided for use by classs that do not directly expose Firewall properties.|
Name or IP address of firewall (optional).If a FirewallHost is given, requested connections will be authenticated through the specified firewall
If the FirewallHost setting is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, the FirewallHost setting is set to the corresponding address. If the search is not successful, an error is returned.
NOTE: This is the same as firewall_host. This setting is provided for use by classs that do not directly expose Firewall properties.
Password to be used if authentication is to be used when connecting through the firewall.If FirewallHost is specified, the FirewallUser and FirewallPassword settings
are used to connect and authenticate to the given firewall. If the authentication fails, the class fails with an error.
NOTE: This is the same as firewall_password. This setting is provided for use by classs that do not directly expose Firewall properties.
The TCP port for the FirewallHost;.Note that the FirewallPort is set automatically when FirewallType is set to a valid value.
NOTE: This is the same as firewall_port. This setting is provided for use by classs that do not directly expose Firewall properties.
Determines the type of firewall to connect through.The appropriate values are as follows:
NOTE: This is the same as firewall_type. This setting is provided for use by classs that do not directly expose Firewall properties.
A user name if authentication is to be used connecting through a firewall.If the FirewallHost is specified, the FirewallUser and FirewallPassword
settings are used to connect and authenticate to the Firewall. If the authentication fails, the class fails with an error.
NOTE: This is the same as firewall_user. This setting is provided for use by classs that do not directly expose Firewall properties.
The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.When set, TCPKeepAlive will automatically be set to true.
A TCP keep-alive packet will be sent after a period of inactivity as
defined by KeepAliveTime. If no acknowledgement is received from the remote host the keep-alive packet
will be re-sent. This setting specifies the interval at which the successive keep-alive packets are sent in milliseconds.
This system default if this value is not specified here is 1 second.
Note: This value is not applicable in Java or MAC.
The inactivity time in milliseconds before a TCP keep-alive packet is sent.When set, TCPKeepAlive will automatically be set to true.
By default the operating system will determine the
time a connection is idle before a TCP keep-alive packet is sent. This system default if this value is not specified here is 2 hours. In many
cases a shorter interval is more useful. Set this value to the desired interval in milliseconds.
Note: This value is not applicable in Java.
When set to True, connections are terminated gracefully.This property controls how a connection is closed. The default is True.
In the case that Linger is True (default), there are two scenarios for determining how long the connection will linger. The first, if LingerTime is 0 (default), the system will attempt to send pending data for a connection until the default IP protocol timeout expires.
In the second scenario, LingerTime is a positive value, the system will attempt to send pending data until the specified LingerTime is reached. If this attempt fails, then the system will reset the connection.
The default behavior (which is also the default mode for stream sockets) might result in a long delay in closing the connection. Although the class returns control immediately, the system could hold system resources until all pending data is sent (even after your application closes).
Setting this property to False forces an immediate disconnection. If you know that the other side has received all the data you sent (by a client acknowledgment, for example), setting this property to False might be the appropriate course of action.
|LingerTime: Time in seconds to have the connection linger. LingerTime is the time, in seconds, to leave the socket connection linger. This value is 0 by default, which means it will use the default IP protocol timeout.|
The name of the local host through which connections are initiated or accepted.
The local_host setting contains the name of the local host
as obtained by the gethostname() system call, or if the
user has assigned an IP address, the value of that address.
In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.
If the class is connected, the local_host setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).
The port in the local host where the class binds.
This must be set before a connection is
attempted. It instructs the class to bind to a specific
port (or communication endpoint) in the local machine.
Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by local_port after the connection is established.
local_port cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.
This; setting is useful when trying to connect to services that require a trusted port in the client side. An example is the remote shell (rsh) service in UNIX systems.
The maximum amount of data to accumulate when no EOL is found.MaxLineLength is the size of an internal buffer, which holds received data while waiting for an eol
The minimum value for MaxLineLength is 256 bytes. The default value is 2048 bytes.
|MaxTransferRate: The transfer rate limit in bytes per second.This setting can be used to throttle outbound TCP traffic. Set this to the number of bytes to be sent per second. By default this is not set and there is no limit.|
A semicolon separated list of hosts and IPs to bypass when using a proxy.This setting optionally specifies a semicolon separated list of hostnames or IP addresses to bypass when a proxy is in use.
When requests are made to hosts specified in this property the proxy will not be used. For instance:
Determines whether or not the keep alive socket option is enabled.If set to true, the socket's keep-alive option is enabled and keep-alive packets will be sent periodically
to maintain the connection. Set KeepAliveTime and KeepAliveInterval to
configure the timing of the keep-alive packets.
Note: This value is not applicable in Java.
Whether or not to delay when sending packets.
When true, the socket will send all data that is ready to send at once. When
false, the socket will send smaller buffered packets of data at small intervals.
This is known as the Nagle algorithm.
By default, this config is set to false.
Whether to use IPv6.When set to 0 (default), the class will use IPv4 exclusively.
When set to 1, the class will use IPv6 exclusively. To instruct the class to prefer IPv6 addresses, but use IPv4 if IPv6 is not supported on the system, this setting should be set to 2. The default value is 0.
Possible values are:
SSL Configuration Settings
Controls whether SSL packets are logged when using the internal security API.When the UseInternalSecurityAPI configuration setting is True, this setting controls whether SSL packets should be logged. By default, this setting is False, as it is only useful for debugging purposes.
When enabled, SSL packet logs are output using the on_ssl_status event, which will fire each time an SSL packet is sent or received.
Enabling this setting has no effect if UseInternalSecurityAPI is False.
The path to a directory containing CA certificates.This functionality is available only when the provider is OpenSSL.
The path set by this property should point to a directory containing CA certificates in PEM format. The files each contain one CA certificate. The files are looked up by the CA subject name hash value, which must hence be available. If more than one CA certificate with the same name hash value exist, the extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). OpenSSL recommends to use the c_rehash utility to create the necessary links. Please refer to the OpenSSL man page SSL_CTX_load_verify_locations(3) for details.
Name of the file containing the list of CA's trusted by your application.This functionality is available only when the provider is OpenSSL.
The file set by this property should contain a list of CA certificates in PEM format. The file can contain several CA certificates identified by
... (CA certificate in base64 encoding) ...
sequences. Before, between, and after the certificates text is allowed which can be used e.g. for descriptions of the certificates. Please refer to the OpenSSL man page SSL_CTX_load_verify_locations(3) for details.
A string that controls the ciphers to be used by SSL.This functionality is available only when the provider is OpenSSL.
The format of this string is described in the OpenSSL man page ciphers(1) section "CIPHER LIST FORMAT". Please refer to it for details. The default string "DEFAULT" is determined at compile time and is normally equivalent to "ALL:!ADH:RC4+RSA:+SSLv2:@STRENGTH".
The data to seed the pseudo random number generator (PRNG).This functionality is available only when the provider is OpenSSL.
By default OpenSSL uses the device file "/dev/urandom" to seed the PRNG and setting OpenSSLPrngSeedData is not required. If set, the string specified is used to seed the PRNG.
Determines if the SSL session is reused.
If set to true, the class will reuse the context if and only if the following criteria are met:
The paths to CA certificate files on Unix/Linux.This setting specifies the paths on disk to CA certificate files on Unix/Linux.
The value is formatted as a list of paths separated by semicolons. The class will check for the existence of each file in the order specified. When a file is found the CA certificates within the file will be loaded and used to determine the validity of server certificates.
The default value is:
A newline separated list of CA certificate to use during SSL client authentication.This setting specifies one or more CA certificates to be included in the request when performing
SSL client authentication. Some servers require the entire chain, including CA certificates, to be presented
when performing SSL client authentication. The value of this setting is a newline (CrLf) separated list of certificates. For instance:
-----BEGIN CERTIFICATE----- MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw ... eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w F0I1XhM+pKj7FjDr+XNj -----END CERTIFICATE----- \r \n -----BEGIN CERTIFICATE----- MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp .. d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA -----END CERTIFICATE-----
Whether to check the Certificate Revocation List for the server certificate.This setting specifies whether the class will check the Certificate Revocation List specified by the server certificate. If set to True the class will first obtain the list of CRL URLs from the server certificate's CRL distribution points extension. The class will then make HTTP requests to each CRL endpoint to check the validity of the server's certificate. If the certificate has been revoked or any other issues are found during validation the class fails with an error.
When set to False (default) the CRL check will not be performed by the class.
The minimum cipher strength used for bulk encryption.
This minimum cipher strength largely dependent on the security modules installed
on the system. If the cipher strength specified is not supported,
an error will be returned when connections are initiated.
Please note that this setting contains the minimum cipher strength requested from the security library. The actual cipher strength used for the connection is shown by the on_ssl_status event.
Use this setting with caution. Requesting a lower cipher strength than necessary could potentially cause serious security vulnerabilities in your application.
The cipher suite to be used in an SSL negotiation.The enabled cipher suites to be used in SSL negotiation.
By default, the enabled cipher suites will include all available ciphers ("*").
The special value "*" means that the class will pick all of the supported cipher suites. If SSLEnabledCipherSuites is set to any other value, only the specified cipher suites will be considered.
Multiple cipher suites are separated by semicolons.
Example values when UseInternalSecurityAPI is False (default):
obj.config("SSLEnabledCipherSuites=*"); obj.config("SSLEnabledCipherSuites=CALG_AES_256"); obj.config("SSLEnabledCipherSuites=CALG_AES_256;CALG_3DES");Possible values when UseInternalSecurityAPI is False (default) include:
obj.config("SSLEnabledCipherSuites=*"); obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA"); obj.config("SSLEnabledCipherSuites=TLS_DHE_DSS_WITH_AES_128_CBC_SHA;TLS_DH_ANON_WITH_AES_128_CBC_SHA");Possible values when UseInternalSecurityAPI is True include:
When TLS 1.3 is negotiated (see SSLEnabledProtocols) only the following cipher suites are supported:
Used to enable/disable the supported security protocols.Used to enable/disable the supported security protocols.
Not all supported protocols are enabled by default (the value of this setting is 4032). If you want more granular control over the enabled protocols, you can set this property to the binary 'OR' of one or more of the following values:
Note: TLS 1.1 and TLS1.2 support are only available starting with Windows 7.
Note: Enabling TLS 1.3 will automatically set UseInternalSecurityAPI to True.
Whether the renegotiation_info SSL extension is supported.This setting specifies whether the renegotiation_info SSL extension will be used in the request when using the internal security API.
This setting is True by default, but can be set to False to disable the extension.
This setting is only applicable when UseInternalSecurityAPI is set to True.
Whether the entire certificate chain is included in the SSLServerAuthentication event.This setting specifies whether the Encoded parameter of the on_ssl_server_authentication event contains
the full certificate chain. By default this value is False and only the leaf certificate will be present
in the Encoded parameter of the on_ssl_server_authentication event.
If set to True all certificates returned by the server will be present in the Encoded parameter of the on_ssl_server_authentication event. This includes the leaf certificate, any intermediate certificate, and the root certificate.
Returns the negotiated ciphersuite.Returns the ciphersuite negotiated during the SSL handshake.
Returns the negotiated ciphersuite strength.Returns the strength of the ciphersuite negotiated during the SSL handshake.
Returns the negotiated ciphersuite.Returns the ciphersuite negotiated during the SSL handshake represented as a single string.
Returns the negotiated key exchange algorithm.Returns the key exchange algorithm negotiated during the SSL handshake.
Returns the negotiated key exchange algorithm strength.Returns the strenghth of the key exchange algorithm negotiated during the SSL handshake.
Returns the negotiated protocol version.Returns the protocol version negotiated during the SSL handshake.
The name of the security provider to use.
Change this setting to use security providers other than the system default.
Use this setting with caution. Disabling SSL security or pointing to the wrong provider could potentially cause serious security vulnerabilities in your application.
The special value "*" (default) picks the default SSL provider defined in the system.
Note: On Windows systems, the default SSL Provider is "Microsoft Unified Security Protocol Provider" and cannot be changed .
Flags that control certificate verification.The following flags are defined (specified in hexadecimal
notation). They can be or-ed together to exclude multiple
This functionality is currently not available when the provider is OpenSSL.
A newline separated list of CA certificate to use during SSL server certificate validation.This setting optionally specifies one or more CA certificates to be used when verifying the server certificate. When verifying the server's certificate the certificates trusted by the system will be used as part of the verification process. If the server's CA certificates are not installed to the trusted system store, they may be specified here so they are included when performing the verification process. This setting should only be set if the server's CA certificates are not already trusted on the system and cannot be installed to the trusted system store.
The value of this setting is a newline (CrLf) separated list of certificates. For instance:
Defines the allowed TLS 1.2 signature algorithms when UseInternalSecurityAPI is True.This setting specifies the allowed server certificate signature algorithms when UseInternalSecurityAPI is
True and SSLEnabledProtocols is set to allow TLS 1.2.
When specified the class will verify that the server certificate signature algorithm is among the values specified in this setting. If the server certificate signature algorithm is unsupported the class fails with an error.
The format of this value is a comma separated list of hash-signature combinations. For instance:
IPPort.Config("UseInternalSecurityAPI=true"); IPPort.Config("SSLEnabledProtocols=3072"); //TLS 1.2 IPPort.Config("TLS12SignatureAlgorithms=sha256-rsa,sha256-dsa,sha1-rsa,sha1-dsa");The default value for this setting is sha512-ecdsa,sha512-rsa,sha512-dsa,sha384-ecdsa,sha384-rsa,sha384-dsa,sha256-ecdsa,sha256-rsa,sha256-dsa,sha224-ecdsa,sha224-rsa,sha224-dsa,sha1-ecdsa,sha1-rsa,sha1-dsa.
In order to not restrict the server's certificate signature algorithm, specify an empty string as the value for this setting, which will cause the signature_algorithms TLS 1.2 extension to not be sent.
The supported groups for ECC.This setting specifies a comma separated list of named groups used in TLS 1.2 for ECC.
The default value is ecdhe_secp256r1,ecdhe_secp384r1,ecdhe_secp521r1.
When using TLS 1.2 and UseInternalSecurityAPI is set to True, the values refer to the supported groups for ECC. The following values are supported:
The groups for which to pregenerate key shares.This setting specifies a comma separated list of named groups used in TLS 1.3 for key exchange.
The groups specified here will have key share data pregenerated locally before establishing a connection.
This can prevent an additional round trip during the handshake if the group is supported by the server.
The default value is set to balance common supported groups and the computational resources required to generate key shares. As a result only some groups are included by default in this setting.
Note: All supported groups can always be used during the handshake even if not listed here, but if a group is used which is not present in this list it will incur an additional round trip and time to generate the key share for that group.
In most cases this setting does not need to be modified. This should only be modified if there is a specific reason to do so.
The default value is ecdhe_x25519,ecdhe_secp256r1,ecdhe_secp384r1,ffdhe_2048,ffdhe_3072
The values are ordered from most preferred to least preferred. The following values are supported:
The allowed certificate signature algorithms.This setting holds a comma separated list of allowed signature algorithms. Possible values are:
The supported groups for (EC)DHE key exchange.This setting specifies a comma separated list of named groups used in TLS 1.3 for key exchange.
This setting should only be modified if there is a specific reason to do so.
The default value is ecdhe_x25519,ecdhe_x448,ecdhe_secp256r1,ecdhe_secp384r1,ecdhe_secp521r1,ffdhe_2048,ffdhe_3072,ffdhe_4096,ffdhe_6144,ffdhe_8192
The values are ordered from most preferred to least preferred. The following values are supported:
Socket Configuration Settings
Determines whether timeouts are inactivity timeouts or absolute timeouts.If AbsoluteTimeout is set to True, any method which does not complete within Timeout seconds
will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.
Note: This option is not valid for UDP ports.
|FirewallData: Used to send extra data to the firewall.When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g. headers for custom authentication schemes).|
The size in bytes of the incoming queue of the socket.
This is the size of an internal queue in the TCP/IP stack.
You can increase or decrease its size depending on the amount
of data that you will be receiving. Increasing the value of the
InBufferSize setting can provide significant improvements in
performance in some cases.
Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.
The size in bytes of the outgoing queue of the socket.This is the size of an internal queue in the TCP/IP stack.
You can increase or decrease its size depending on the amount
of data that you will be sending. Increasing the value of the
OutBufferSize setting can provide significant improvements in
performance in some cases.
Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.
Base Configuration Settings
|BuildInfo: Information about the product's build.When queried, this setting will return a string containing information about the product's build.|
The system code page used for Unicode to Multibyte translations.The default code page is Unicode UTF-8 (65001).
The following is a list of valid code page identifiers:
Information about the current license.When queried, this setting will return a string containing information about the license this instance of a class is using. It will return the following information:
|ProcessIdleEvents: Whether the class uses its internal event loop to process events when the main thread is idle.If set to False, the class will not fire internal idle events. Set this to false to use the class in a background thread on macOS. By default this setting is True.|
|SelectWaitMillis: The length of time in milliseconds the class will wait when DoEvents is called if there are no events to process.If there are no events to process when do_events is called, the class will wait for the amount of time specified here before returning. The default value is 20.|
|UseInternalSecurityAPI: Tells the class whether or not to use the system security libraries or an internal implementation. By default the class will use the system security libraries to perform cryptographic functions. Setting this to True tells the class to use the internal implementation instead of using the system's security API.|