1.5. Configuring netconsole
1.5. Configuring netconsole If disk logging fails or using the serial console is not possible, you might need to use kernel debugging. The netconsole kernel module enables to log kernel messages to another computer over the network. To be able to use netconsole , you need to have an rsyslog server that is properly configured on your network. Procedure 1.1. Configuring an rsyslog server for netconsole Configure the rsyslogd daemon to listen on the 514/udp port and receive messages from the network by uncommenting the following lines in the MODULES section of the /etc/rsyslog.conf file: Restart the rsyslogd service for the changes to take effect: Verify that rsyslogd is listening on the 514/udp port: The 0.0.0.0:syslog and [::]:syslog values in the netstat -l output mean that rsyslogd is listening on default netconsole port defined in the /etc/services file: Netconsole is configured using the /etc/sysconfig/netconsole file, which is a part of the initscripts package. This package is installed by default and it also provides the netconsole service. If you want to configure a sending machine, follow this procedure: Procedure 1.2. Configuring a Sending Machine Set the value of the SYSLOGADDR variable in the /etc/sysconfig/netconsole file to match the IP address of the syslogd server. For example: Restart the netconsole service for the changes to take effect: Enable netconsole.service to run after rebooting the system: View the netconsole messages from the client in the /var/log/messages file (default) or in the file specified in rsyslog.conf . Note By default, rsyslogd and netconsole.service use port 514. To use a different port, change the following line in /etc/rsyslog.conf to the required port number: On the sending machine, uncomment and edit the following line in the /etc/sysconfig/netconsole file: For more information about netconsole configuration and troubleshooting tips, see Netconsole Kernel Documentation .
USDModLoad imudp USDUDPServerRun 514 ]# systemctl restart rsyslog ]# netstat -l | grep syslog udp 0 0 0.0.0.0:syslog 0.0.0.0:* udp6 0 0 [::]:syslog [::]:* ]USD cat /etc/services | grep syslog syslog 514/udp syslog-conn 601/tcp # Reliable Syslog Service syslog-conn 601/udp # Reliable Syslog Service syslog-tls 6514/tcp # Syslog over TLS syslog-tls 6514/udp # Syslog over TLS syslog-tls 6514/dccp # Syslog over TLS SYSLOGADDR= 192.168.0.1 ]# systemctl restart netconsole.service ]# systemctl enable netconsole.service ]# cat /var/log/messages USDUDPServerRun <PORT> SYSLOGPORT=514