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CentOS Linux

"The CentOS Project is a community-driven free software effort focused on delivering a robust open source ecosystem." - https://www.centos.org/

CentOS 7

  • Released 2014-07-07

New things in CentOS 7

  • firewalld manages the firewall
  • hostnamectl changes the hostname and applies the setting immediately
  • journalctl shows log files of services launched by systemd
  • systemctl manages systemd services

Initial setup

Set up some base parameters on a fresh instance

yum install -y bash-completion bc curl git lsof mlocate mutt net-snmp ntpd smartmontools strace sysstat vim wget
ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime
ntpdate {0..3}.pool.ntp.org
systemctl start ntpd

CentOS 6

  • Released 2011-07-10

CentOS 6 Initial Setup

yum install -y ntp
chkconfig --levels 345 ntpd on && ntpdate time.apple.com && service ntpd start
yum upgrade -y
yum install -y arping avahi avahi-tools bc bind-utils curl elinks fping lsof net-snmp man mlocate mutt openssh openssh-clients openssh-server perl-Crypt-SSLeay perl-libwww-perl rsync strace vim wget yum-cron
ln -sf /usr/share/zoneinfo/America/Los_Angeles /etc/localtime
chkconfig --levels 345 yum-cron on && service yum-cron start
yum install -y dcfldd nfs-utils smartmontools dmidecode lshw dstat htop iotop
chkconfig --levels 345 smartd on && service smartd start

Tweaks and Tricks

Get past protected lib problems

yum update --setopt=protected_multilib=false --skip-broken

Enable DHCP Hostname for DNS resolution

add "DHCP_HOSTNAME=whatever" to /etc/sysconfig/network-scripts/ifcfg-eth0

Install OS from USB

Show installed repository keys

rpm -q gpg-pubkey --qf '%{name}-%{version}-%{release} --> %{summary}\n'

DHCP with DDNS hostname

Model your /etc/sysconfig/network-scripts/ifcfg-eth0 like this:

TYPE=Ethernet
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
## Without the following line, dhclient will not update /etc/resolv.conf and may not get an IP address at all
DHCP_HOSTNAME=some_hostname
  • To configure your hostname, edit /etc/sysconfig/network and add HOSTNAME=
  • You also may need to delete these files:
rm -f /etc/dhclient-eth?.conf /var/lib/dhclient/dhclient-eth?.leases /etc/udev/rules.d/70-persistent-net.rules /etc/sysconfig/network-scripts/ifcfg-eth1

Bond Configs

$ cat /etc/modprobe.d/bond0.conf
alias bond0 bonding
options bond0 max_bonds=1 fail_over_mac=2 mode=1 num_grat_arp=2 primary=em1 primary_reselect=1 arp_validate=1 arp_interval=100 arp_ip_target=10.1.5.15,10.1.1.1

See Also