Netconsole howto

This document (7000330) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10
SUSE Linux Enterprise Server 9

Situation

Kernel boot messages need to be saved after a server crash/hang but access to a serial console is not available.

Resolution

Use netconsole to send kernel boot messages to another server on the network.

Additional Information

Senderconfiguration:

Configure the system that will generate the kernel messages as following:

Load the netconsole module at boot time. Edit /etc/sysconfig/kernel and add:
MODULES_LOADED_ON_BOOT="netconsole"
Set netconsole module options. Edit /etc/modprobe.conf.local and add:
options netconsole netconsole=4444@10.0.0.1/eth0,6666@10.0.0.2/00:1A:A0:D2:55:66

Explanation:

Sender source port: 4444
Sender IP: 10.0.0.1
Sender NIC: eth0
Recipient listening port: 6666
Recipient IP: 10.0.0.2
Recipient MAC: 00:1A:A0:D2:55:66

Note:
In case the remote logging client is on a separate subnet than the sender, specify the MAC address of the default gateway instead of the actual MAC address of the recipient system.

Recipient configuration:

Open firewall port. Edit /etc/sysconfig/SuSEfirewall2 and set:
FW_ALLOW_INCOMING_HIGHPORTS_UDP="6666"
Restart firewall:
rcSuSEfirewall2 restart
Configure syslog-ng. Edit/etc/syslog-ng/syslog-ng and add:
source net { udp(ip("0.0.0.0") port(6666)); };
destination netconsole { file("/var/log/$HOST-netconsole.log"); };
log { source(net); destination(netconsole); };
Restart syslog-ng:
rcsyslog restart

On the recipient system, logs are written to/var/log/$hostname-netconsole.log

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.