TCPLOG (JANUS DEFINE parameter)

TCPLOG filename — Log TCP activity to flatfile

TCPLOG is a parameter on JANUS DEFINE, which defines and sets characteristics of a Janus port.

A Janus Web Server port definition parameter, TCPLOG tells Janus Web Server to log in a sequential dataset all inbound and outbound TCP data transmitted for this port. The dataset name is specified as the value that follows the TCPLOG keyword.

The log file is opened and cleared when the associated Janus port is started, and it is closed when the port is stopped or if an error occurs writing data to the dataset.

The log data is written in variable length blocks. The first four bytes of a block contain the length of the block. Each block contains at least one record. No character translation or formatting is done for the actual TCP data. Since the blocks are standard variable length blocks, they all start with a Block Descriptor Word (BDW) which consists of a halfword block length followed by two bytes of zero.

The layout of the records in each block is described in detail below:

Offset	Length	Type	Description
0	2	Unsigned binary	RDW (Record descriptor word): the length of the current record
2	2	Unused	Unused
4	8	Unsigned binary	Unique TCP connection number
12	4	Unsigned binary	Record number
16	8	Unsigned binary	Time of day in clock units
24	4	Unsigned binary	Remote IP address
28	4	Unsigned binary	Local IP address
32	2	Unsigned binary	Remote port number
34	2	Unsigned binary	Local port number
36	1	EBCDIC character	Direction: S (Sent) or R (Received)
37	1	Unused	Unused
38	2	Unsigned binary	Length of TCP data
40	v	Binary	Any TCP data

The TCPLOG dataset cannot be shared by multiple Janus ports.

The TCPLOG parameter is valid only for WEBSERV ports.

See also

• List of Janus commands
• List of JANUS DEFINE parameters