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11.9. Configuring netconsole
The
netconsole
kernel module enables logging of kernel messages over the network to another computer. It allows kernel debugging when disk logging fails or when using the serial console is not possible.
Configuring a Listening Machine
To enable receiving
netconsole
logging messages, install the rsyslog package:
]# yum install rsyslog
To configure
rsyslogd
to listen on the 514/UDP port and receive messages from the network, uncomment the following lines in the MODULES
section of /etc/rsyslog.conf
:
$ModLoad imudp $UDPServerRun 514
Restart the
rsyslogd
service for the changes to take effect:
]# service rsyslog restart
To verify that
rsyslogd
is listening on the 514/udp port, use the following command:
]# netstat -l | grep syslog
udp 0 0 *:syslog *:*
udp 0 0 *:syslog *:*
The
0 *:syslog
value in the netstat -l
output mean that rsyslogd
is listening on default netconsole
port, which is defined in the /etc/services
file:
]$ 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
Configuring a Sending Machine
In Red Hat Enterprise Linux 6,
netconsole
is configured using the file /etc/sysconfig/netconsole
, which is part of the initscripts package. This package is installed by default and it also provides the netconsole
service.
To configure 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:
SYSLOGADDR=192.168.0.1
Restart the
netconsole
service so the changes take effect. Then, use the chkconfig
command to ensure netconsole
service starts automatically after next reboot:
]#service netconsole restart
Initializing netconsole [ OK ] ]#chkconfig netconsole on
By default, the
rsyslogd
server writes the netconsole
messages from the client in /var/log/messages
or in the file specified in rsyslog.conf
.
Note
To set
rsyslogd
and netconsole
to use a different port, change the following line in /etc/rsyslog.conf
to the desired port number:
$UDPServerRun <PORT>
On the sending machine, uncomment and edit the following line in the
/etc/sysconfig/netconsole
file:
SYSLOGPORT=514
For more information about
netconsole
configuration and troubleshooting tips, see Netconsole Kernel Documentation.