It is really a good idea to have one central logging host for security and performance reason. For example monitoring log files will help you to detect:
* Security risks (you can see failed login attempt, port scan etc) analysis
* Troubleshoot user login problem
* Save disk space
* If hard disk crashed on other hosts old logs will be available from centralized loghost
Linux (and other UNIX like systems) use sysklogd (or syslogd) utility. It is system logging facility. It support of both internet and unix domain sockets enables this utility package to support both local and remote logging from DSL/ADSL router or other hosts in your network.
Prepare syslogd to accept remote logging message
Open file /etc/init.d/sysklogd under Debian Linux to configure syslogd to accept remote message.
# vi /etc/init.d/sysklogd
Locate line SYSLOGD and edit it as follows:
SYSLOGD="-r"
The option (-r) will enable the facility to receive message from the network using an internet domain socket with the syslog service. The default is to not receive any messages from the network.
Save file and exit to shell prompt. Restart the sysklogd:
# /etc/init.d/sysklogd restart
A note about RHEL / CentOS / Fedora Linux User
If you are using Red Hat or Fedora Linux, edit file /etc/sysconfig/syslog:
# vi /etc/sysconfig/syslog
Make changes:
SYSLOGD="-r"
Restart syslogd:
# service syslog restart
Open UDP port 514
If you are, using iptables based firewall, insert following rule to your iptables script to accept connection from your network:
MYNET=192.168.1.0/24 SLSERVER=192.168.1.100 iptables -A INPUT -p udp -s $MYNET --sport 1024:65535 -d $SLSERVER --dport 514 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -p udp -s $SLSERVER --sport 514 -d $MYNET --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
192.168.1.100 is IP address of syslogd server. You need to restrict access to syslogd within your network (192.168.1.0/24) only.
Configure the Router to logging message to a centralized loghost
You can open web configuration interface and type IP address of centralized loghost (192.168.1.100) and port 514. Save configuration and reboot router.
Configure Linux or Unix host to logging message to a centralized loghost
You need to open syslog configuration file /etc/syslog.conf:
# vi /etc/syslog.conf
Setup syslogd to send all important message related to auth to loghost IP 192.168.1.100 (or use FQDN if configured)
*.*;auth,authpriv.none @192.168.1.100
OR
*.*;auth,authpriv.none @loghost.mydomain.com.
Restart sysklogd (Debian Linux):
# /etc/init.d/sysklogd restart
OR
Restart syslogd under Red Hat/Fedora / CentOS Linux
# service syslog restart
If required open outgoing UDP 514 port from other hosts:
# SYSLOG outgoing client request iptables -A OUTPUT -p udp -s 192.168.1.100 --sport 1024:65535 -d 192.168.1.5 --dport 514 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -p udp -s 192.168.1.5 --sport 514 -d 192.168.1.100 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
Windows NT/2000/XP/Vista Desktop system
You can force your Windows NT/2000/XP desktop to log all messages to a centralized loghost. However, Windows do not have in build system to log message to remote Unix syslogd server. You can use NTsyslog program, which runs as a service under Windows NT based operating systems. It formats all System, Security, and Application events into a single line and sends them to a syslogd host.