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CentOS 5.x notes

·2 mins
linux centos
Table of Contents

My personal notebook for CentOS 5.x installations.

Enable LDAP authentication #

If the IP of your LDAP server is 10.10.10.10 and your base dn is ou=users,dc=yourdomain,dc=com then the following command enables LDAP authentication:

authconfig --enableldap --enableldapauth \
           --ldapserver=10.10.10.10      \
           --ldapbasedn=ou=users,dc=yourdomain,dc=com \
           --enablecache --useshadow                  \
           --enablelocauthorize --enablemkhomedir --update

Enable network bonding #

You need two network interfaces. Interface eth0 configuration recides in /etc/sysconfig/network-scripts/ifcfg-eth0:

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes

The same holds for eth1 in /etc/sysconfig/network-scripts/ifcfg-eth1:

DEVICE=eth1
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes

The bonded interface is in /etc/sysconfig/network-scripts/ifcfg-bond0

DEVICE=bond0
BOOTPROTO=dhcp
ONBOOT=yes

Finally the bonding mode is set in /etc/modprobe.conf:

...
alias bond0 bonding
options bond0 mode=0 miimon=80

Permit specific incoming connections #

The following script permits incoming connections from 192.168.3.10/32 and 192.168.3.3/32:

#!/bin/bash
# flush all current rules
iptables -F
# permit ssh only from control station and sgd
iptables -A INPUT -p tcp -s 192.168.3.10/255.255.255.255 --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -s 192.168.3.3/255.255.255.255 --dport 22 -j ACCEPT
# drop any other traffic
iptables -P INPUT DROP
iptables -P FORWARD DROP
# permit all outbound traffic
iptables -P OUTPUT ACCEPT
# do not block the lo interface
iptables -A INPUT -i lo -j ACCEPT
# do not block established or related traffic
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# save our settings
/sbin/service iptables save

A minimum set of services #

The following script disables a lot of services. Only the bare minimum is left active:

#!/bin/bash
chkconfig acpid off
chkconfig anacron off
chkconfig atd off
chkconfig auditd off
chkconfig autofs off
chkconfig avahi-daemon off
chkconfig bluetooth off
chkconfig cpuspeed off
chkconfig cups off
chkconfig firstboot off
chkconfig gpm off
chkconfig haldaemon off
chkconfig hidd off
chkconfig hplip off
chkconfig ip6tables off
chkconfig isdn off
chkconfig kudzu off
chkconfig mcstrans off
chkconfig mdmonitor off
chkconfig messagebus off
chkconfig pcscd off
chkconfig rawdevices off
chkconfig readahead_early off
chkconfig restorecond off
chkconfig rpcgssd off
chkconfig rpcidmapd off
chkconfig sendmail off
chkconfig smartd off
chkconfig xfs off
chkconfig yum-updatesd off

Kill zombie GNOME processes #

VDI access left behind a lot of zombie processes. The following script kills all of them:

#!/bin/bash
for P in `ps -ef | tr -s ' ' | egrep -v " ..:.. " | egrep -v "^UID|^root|^rpc|^ntp|^nscd" | tr -s ' ' | cut -d " " -f 2`
do
        kill -9 ${P}
done
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