Both the extended DHCP local server and the extended DHCP relay agent support tracing operations. DHCP tracing operations track extended DHCP operations and record them in a log file. The error descriptions captured in the log file provide detailed information to help you solve problems.
By default, nothing is traced. When you enable the tracing operation, the default tracing behavior is as follows:
You can optionally configure the maximum file size to be from 10 KB through 1 gigabyte (GB). You can also specify the number of trace files to be from 2 through 1000. (For more information about how log files are created, see the JUNOS System Log Messages Reference.)
To configure DHCP local server and DHCP relay agent tracing operations:
- [edit system services dhcp-local-server]
- user@host# edit traceoptions
- [edit forwarding-options dhcp-relay]
- user@host# edit traceoptions
See Configuring the Number and Size of Extended DHCP Log Files.
See Configuring a Regular Expression for Extended DHCP Lines to Be Logged.
The extended DHCP traceoptions operations are described in the following sections:
By default, the name of the file that records trace output is jdhcpd. You can specify a different name by including the file option:
To configure the filename for DHCP local server and DHCP relay agent tracing operations:
- [edit system services dhcp-local-server traceoptions]
- user@host# set file dhcp_logfile_1
By default, when the trace file reaches 128 kilobytes (KB) in size, it is renamed filename.0, then filename.1, and so on, until there are three trace files. Then the oldest trace file (filename.2) is overwritten.
You can optionally configure the maximum file size to be from 10 KB through 1 gigabyte (GB). You can also specify the number of trace files to be from 2 through 1000.
For example, you can set the maximum file size to 2 MB, and the maximum number of files to 20. When the file that receives the output of the tracing operation (filename) reaches 2 MB, filename is renamed filename.0, and a new file called filename is created. When the new filename reaches 2 MB, filename.0 is renamed filename.1 and filename is renamed filename.0. This process repeats until there are 20 trace files. Then the oldest file (filename.19) is overwritten by the newest file (filename.0).
To configure the number and size of trace files:
- [edit system services dhcp-local-server traceoptions]
- user@host# set file dhcp_logfile_1 files 20
size 2097152
By default, log files can be accessed only by the user who configures the tracing operation. You can enable all users to read the log file and you can explicitly set the default behavior of the log file.
To specify that all users can read the log file:
- [edit system services dhcp-local-server traceoptions]
- user@host# set file dhcp_logfile_1 world-readable
To explicitly set the default behavior, in which the log file can only be read by the user who configured tracing:
- [edit system services dhcp-local-server traceoptions]
- user@host# set file dhcp_logfile_1 no-world-readable
By default, the trace operation output includes all lines relevant to the logged events.
You can refine the output by including regular expressions that will be matched.
To configure regular expressions to be matched:
- [edit system services dhcp-local-server traceoptions]
- user@host# set file dhcp_logfile_1 match regex
By default, only important events are logged. You can specify which trace operations are logged by including specific tracing flags. The following table describes the flags that you can include.
To configure the flags for the events to be logged:
- [edit system services dhcp-local-server traceoptions]
- user@host# set flag packet-option