Show Contents / Index / Search

Server Debugging

Server event messages can arise from different sources and be controlled by different configuration options. The following table summarizes sshd command-line options and server configuration keywords that affect logging; and describes where to find the output.

To

Use

Output Location

Notes

Debug a single client connection

-d debug_level

stderr

Use 1, 2, 3, or 99. (Values 4-98 are accepted, but are equivalent to 3.) With this option, sshd terminates after the first client connection closes.

This option is independent of the setting for LogLevel.

Enable persistent debugging

-D debug_level

/etc/ssh2

A debug file is created using the following file name format: debugYYMMDD_HHMMSS_uniqueID.

This option is independent of the setting for LogLevel.

Suppress debug messages

-q
QuietMode

N/A — affects syslog output only

This option overrides LogLevel.

View server startup messages

LogLevel

stderr

Output to stderr includes errors and warnings found while parsing sshd2_config.