SysLog Component

Properties   Methods   Events   Config Settings   Errors  

The Syslog component is used to send and receive network system log packets.

Syntax

TipwSysLog

Remarks

The Syslog component implements a lightweight BSD syslog client as specified in RFC 3164 (User Datagram Protocol [UDP]), RFC 5425 (Secure Sockets Layer/Transport Layer Security [SSL/TLS]), and RFC 6587 (Transmission Control Protocol [TCP]). The component is used to send and receive BSD system network logging packets.

The first step in using the Syslog component is to set LocalHost and LocalPort to the interface and port on which the host will be receiving syslog packets, and then call the Activate method. For each packet, the component will parse the headers and message and fire a PacketIn event.

Property List

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The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the component with short descriptions. Click on the links for further details.

Active Property (SysLog Component)

This property indicates whether the component is active.

Syntax

property Active: Boolean read get_Active;

Default Value

false

Remarks

This property indicates whether the component is currently active and can send or receive data. Use the Activate and Deactivate methods to control whether the component is active.

This property is read-only and not available at design time.

LocalHost Property (SysLog Component)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

property LocalHost: String read get_LocalHost write set_LocalHost;

Default Value

''

Remarks

This property 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 multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the component initiate connections (or accept in the case of server components) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the component is connected, the LocalHost property 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 multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalPort Property (SysLog Component)

This property indicates the port in the local host where Syslog binds.

Syntax

property LocalPort: Integer read get_LocalPort write set_LocalPort;

Default Value

514

Remarks

The LocalPort property must be set before Syslog is activated. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting it to 0 enables the Transmission Control Protocol (TCP)/IP stack to choose a port at random. The chosen port will be shown by the LocalPort property after the connection is established.

LocalPort cannot be changed once the component is Active. Any attempt to set the LocalPort property when the component is Active will generate an error.

The LocalPort property is useful when trying to connect to services that require a trusted port in the client side.

RemoteHost Property (SysLog Component)

This property sets a specific host for outgoing log packets.

Syntax

property RemoteHost: String read get_RemoteHost write set_RemoteHost;

Default Value

'255.255.255.255'

Remarks

When a call is made to the SendPacket method, the component will send it to whatever value is in RemoteHost. The default value is the broadcast address, "255.255.255.255".

RemotePort Property (SysLog Component)

This property sets a specific port for outgoing log packets.

Syntax

property RemotePort: Integer read get_RemotePort write set_RemotePort;

Default Value

514

Remarks

When a call is made to the SendPacket method, the component will send to RemoteHost on RemotePort. The default value is 514, the standard port as defined in the BSD syslog RFC 3164.

SSLAcceptServerCert Property (SysLog Component)

Instructs the component to unconditionally accept the server certificate that matches the supplied certificate.

Syntax

property SSLAcceptServerCert: TipwCertificate read get_SSLAcceptServerCert write set_SSLAcceptServerCert;

Remarks

If it finds any issues with the certificate presented by the server, the component will normally terminate the connection with an error.

You may override this behavior by supplying a value for SSLAcceptServerCert. If the certificate supplied in SSLAcceptServerCert is the same as the certificate presented by the server, then the server certificate is accepted unconditionally, and the connection will continue normally.

Note: This functionality is provided only for cases in which you otherwise know that you are communicating with the right server. If used improperly, this property may create a security breach. Use it at your own risk.

Please refer to the Certificate type for a complete list of fields.

SSLAuthenticateClients Property (SysLog Component)

If set to True, the server asks the client(s) for a certificate.

Syntax

property SSLAuthenticateClients: Boolean read get_SSLAuthenticateClients write set_SSLAuthenticateClients;

Default Value

false

Remarks

This property is used in conjunction with the SSLClientAuthentication event. Please refer to the documentation of the SSLClientAuthentication event for details.

SSLCert Property (SysLog Component)

The certificate to be used during Secure Sockets Layer (SSL) negotiation.

Syntax

property SSLCert: TipwCertificate read get_SSLCert write set_SSLCert;

Remarks

This property includes the digital certificate that the component will use during SSL negotiation. Set this property to a valid certificate before starting SSL negotiation. To set a certificate, you may set the Encoded field to the encoded certificate. To select a certificate, use the store and subject fields.

Please refer to the Certificate type for a complete list of fields.

SSLEnabled Property (SysLog Component)

This property indicates whether Secure Sockets Layer/Transport Layer Security (TLS/SSL) is enabled.

Syntax

property SSLEnabled: Boolean read get_SSLEnabled write set_SSLEnabled;

Default Value

false

Remarks

This setting specifies whether TLS/SSL is enabled in the component. When False (default), the component operates in plaintext mode. When True, TLS/SSL is enabled.

Note: TLS/SSL can be used only when UseTCP is True.

This property is not available at design time.

SSLServerCert Property (SysLog Component)

The server certificate for the last established connection.

Syntax

property SSLServerCert: TipwCertificate read get_SSLServerCert;

Remarks

This property contains the server certificate for the last established connection.

SSLServerCert is reset every time a new connection is attempted.

This property is read-only.

Please refer to the Certificate type for a complete list of fields.

UseTCP Property (SysLog Component)

This property specifies whether Transmission Control Protocol (TCP) is used.

Syntax

property UseTCP: Boolean read get_UseTCP write set_UseTCP;

Default Value

false

Remarks

This property specifies whether TCP is used. By default, this property is False and UDP is used. When set to True, TCP will be used as the underlying protocol.

When set to True, the following additional settings are also applicable:

• SSLAuthenticateClients
• SSLEnabled
• SSLAcceptServerCert
• SSLCert
• SSLServerCert
• TCPMessageDelimiter

Activate Method (SysLog Component)

This method enables sending and receiving of data.

Syntax

procedure Activate();

Remarks

This method enables sending and receiving of data. When called, the component will create a communication endpoint (socket) that can be used for sending and receiving User Datagram Protocol (UDP) messages. This method must be called before using the component to send and receive data.

If the UseConnection configuration setting is set to True, then a local association (connection) to the remote host is also created.

Config Method (SysLog Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Deactivate Method (SysLog Component)

This method disables sending and receive of data.

Syntax

procedure Deactivate();

Remarks

This method disables sending and receiving of data. When called, the component will destroy the existing socket and disable data communications.

DoEvents Method (SysLog Component)

This method processes events from the internal message queue.

Syntax

procedure DoEvents();

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

Reset Method (SysLog Component)

This method will reset the component.

Syntax

procedure Reset();

Remarks

This method will reset the component's properties to their default values.

ResolveRemoteHost Method (SysLog Component)

This method resolves the hostname in RemoteHost to an IP address.

Syntax

procedure ResolveRemoteHost();

Remarks

This method resolves the hostname specified by RemoteHost to an IP address. The resolved value is available in the RemoteHost property after this method returns.

In most cases, calling this method is not necessary; the component will resolve the hostname automatically when needed. If DelayHostResolution is True, this method may be called to manually resolve RemoteHost, if desired.

SendPacket Method (SysLog Component)

This method sends a log packet to RemoteHost .

Syntax

procedure SendPacket(Facility: Integer; Severity: Integer; Message: String);

Remarks

System log packets are composed of three main sections, each of which can be broken down into two smaller pieces.

The first section is the PRI, which contains the originating Facility and Severity of the Message. Facility is a value from 0 to 23, with each value being a different part of the system:

Severity is a value from 0 to 7 using the following convention:

The second section contains a timestamp and hostname, both of which are automatically generated by the component. The third section is the Message.

Connected Event (SysLog Component)

This event is fired immediately after a connection completes (or fails).

Syntax

type TConnectedEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

Remarks

This event fires after a connection completes or fails.

StatusCode is the value returned by the system Transmission Control Protocol (TCP)/IP stack. This will be 0 if the connection was successful.

Description contains a human readable description of the status. This will be OK if the connection was successful.

RemoteAddress is the IP address of the remote host.

RemotePort is the port on the remote host.

ConnectionStatus Event (SysLog Component)

This event is fired to indicate changes in a connection state.

Syntax

type TConnectionStatusEvent = procedure (
  Sender: TObject;
  const ConnectionEvent: String;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnectionStatus: TConnectionStatusEvent read FOnConnectionStatus write FOnConnectionStatus;

Remarks

The ConnectionStatus event is fired when the connection state changes: for example, upon completion of a firewall or proxy connection or completion of a security handshake.

The ConnectionEvent parameter indicates the type of connection event. Values may include the following:

StatusCode has the error code returned by the Transmission Control Protocol (TCP)/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Disconnected Event (SysLog Component)

This event is fired when a connection is closed.

Syntax

type TDisconnectedEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

Remarks

This event fires when a connection is closed.

StatusCode is the value returned by the system Transmission Control Protocol (TCP)/IP stack. This will be 0 if the connection was successful.

Description contains a human readable description of the status. This will be OK if the connection was successful.

RemoteAddress is the IP address of the remote host.

RemotePort is the port on the remote host.

Error Event (SysLog Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

PacketIn Event (SysLog Component)

This event fires whenever a system log packet is received.

Syntax

type TPacketInEvent = procedure (
  Sender: TObject;
  FacilityCode: Integer;
  const Facility: String;
  SeverityCode: Integer;
  const Severity: String;
  const Timestamp: String;
  const Hostname: String;
  const Message: String;
  Conforms: Boolean;
  const Packet: String;
  const PacketB: TBytes;
  const SourceAddress: String;
  SourcePort: Integer
) of Object;

property OnPacketIn: TPacketInEvent read FOnPacketIn write FOnPacketIn;

Remarks

System log packets are composed of three main sections, each of which can be broken down into two smaller pieces.

The first section is the PRI, which contains the originating FacilityCode and SeverityCode of the Message. FacilityCode is a value from 0 to 23, with each value being a different part of the system. Facility is a string representation of FacilityCode based on the following convention:

SeverityCode is a value from 0 to 7. Severity is a string representation of SeverityCode using the following convention:

The second section contains the Timestamp and Hostname. Timestamp is a string that should conform to the standard structure "MMM DD, HH:MM:SS". The component will search for the Timestamp and verify that it conforms. If it conforms, the component will set Hostname, otherwise, everything after the PRI will be placed in Message.

If Conforms is True, then the original syslog packet conforms to the syslog RFC and Timestamp, Hostname, and Message will all have valid values. Otherwise, you should parse the contents of Packet to verify the fields manually.

SourceAddress and SourcePort are the address and port from which Packet was sent. This can be an intermediate syslog server that is simply forwarding packets from the original host.

SSLClientAuthentication Event (SysLog Component)

This is event fired when the client presents its credentials to the server.

Syntax

type TSSLClientAuthenticationEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const CertEncoded: String;
  const CertEncodedB: TBytes;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSLClientAuthentication: TSSLClientAuthenticationEvent read FOnSSLClientAuthentication write FOnSSLClientAuthentication;

Remarks

This event fires when a client connects to the component and presents a certificate for authentication. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK").

RemoteAddress is the IP address of the connecting client.

RemotePort is the source port of the connecting client.

CertEncoded is the base64-encoded certificate presented by the client.

CertSubject is the subject of the certificate presented by the client.

CertIssuer is the subject of the issuer of the certificate presented by the client.

Status is the status of the certificate.

Accept defines whether the certificate is accepted.

SSLServerAuthentication Event (SysLog Component)

This event fires when connecting to the server.

Syntax

type TSSLServerAuthenticationEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const CertEncoded: String;
  const CertEncodedB: TBytes;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSLServerAuthentication: TSSLServerAuthenticationEvent read FOnSSLServerAuthentication write FOnSSLServerAuthentication;

Remarks

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

RemoteAddress is the IP address of the server.

RemotePort is the source port of the server.

CertEncoded is the base64-encoded certificate presented by the server.

CertSubject is the subject of the certificate presented by the server.

CertIssuer is the subject of the issuer of the certificate presented by the server.

Status is the status of the certificate.

Accept defines whether the certificate is accepted.

SSLStatus Event (SysLog Component)

This event shows the progress of the secure connection.

Syntax

type TSSLStatusEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  const Message: String
) of Object;

property OnSSLStatus: TSSLStatusEvent read FOnSSLStatus write FOnSSLStatus;

Remarks

The event is fired for informational and logging purposes only. It is used to track the progress of the connection.

RemoteAddress is the IP address of the remote machine.

RemotePort is the port of the remote machine.

Message is the log message.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

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constructor Create();

>

constructor Create(valEncoded: TBytes);

>

constructor Create(valStoreType: TipwCertStoreTypes; valStore: String; valStorePassword: String; valSubject: String);

>

constructor Create(valStoreType: TipwCertStoreTypes; valStore: TBytes; valStorePassword: String; valSubject: String);

Config Settings (SysLog Component)

The component 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 component, access to these internal properties is provided through the Config method.

Syslog Config Settings

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (SysLog Component)

SysLog Errors

UDP Errors

SSL Errors

TCP/IP Errors