Oracle Linux/Quick Reference
yum
update repo cache (agt-get update equivalent)
~$ yum check-update
update all packages
~$ yum update
install software
~$ yum install lynx
search for software
~$ yum search apache
remove software
~$ yum remove lynx
search for package by command
~$ yum whatprovides dig
Add user & add to sudoers
add user
~$ useradd user
you can also add the user, define their home directory, and add them to a group in one line.
~$ useradd username -d <customer_home_dir_path> -G <group_names>
set password for user
~$ passwd user
add to sudoers
~$ visudo ... user ALL=(ALL) ALL
or use the wheel group. Uncomment it:
## Allow people in the group wheel to run all commands %wheel ALL=(ALL) ALL
Add user to the group
~$ sudo usermod -a -G [group] [user] i.e. sudo usermod -a -G sudo Joe check to verify they are part of the group ~$ getent group sudo sudo:x:27:Bob,Joe
determine packages installed & search
~$ rpm -qa | less | grep term
configure date/time
~$ sudo date -s "2 OCT 2006 18:00:00"
netstat
determine gateway
~$ netstat -nr Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 0.0.0.0 10.45.9.1 0.0.0.0 UG 0 0 0 eth0 10.45.9.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
disable selinux
~$ /etc/selinux/config change SELinux=enforcing to SELinux=disabled
check linux version
~$ rpm -qf /etc/redhat-release
release and renew ip (dhcp)
release
~$ sudo dhclient -v -r eth0
renew
~$ sudo dhclient -v eth0
update hostname
Normally you only need to update the hostname in (1) place:
~$ sudo vim /etc/hostname hostname.localhost
However, you may need to change it in these other places (or it may already be changed there)
Make sure your hostname is defined in /etc/sysconfig/network
HOSTNAME=server.fqdn.com
Also for the network config, put your FQDN in the hosts file @ /etc/hosts
127.0.0.1 server.fqdn.com ::1 server.fqdn.com OR 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 ip.address fqdn.hostname
check and change DNS servers
~$ sudo vi /etc/resolv.conf nameserver 8.8.8.8 nameserver 8.8.4.4
Install epel repo
~$ yum install epel-release
Add & configure LDAP authentication for SSH
references
https://docs.oracle.com/cd/E52668_01/E54669/html/ol7-sssd-ldap.html
https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=66854729
https://www.jethrocarr.com/2010/11/17/automatically-creating-home-directories-at-login-time/
Install SSSD
~$ sudo yum install sssd sssd-client
Configure SSSD
You can opt to manually edit the configuration file, like is seen in this link.
Or you can use authconfig to configure it for you, like so:
authconfig --enablesssd --enablesssdauth --enablelocauthorize --enableldap --enableldapauth --ldapserver=<ldap_host> --enableldaptls --ldapbasedn=dc=my-company,dc=my-org --enableshadow --enablerfc2307bis --enablemkhomedir --enablecachecreds --update
You may need to start or restart the service
~$ sudo service sssd restart
Home Directories
Make sure you use the switch --enablemkhomedir when you use authconfig if you want users to have their own home directory.
Sudo access
If you want users to have sudo access, providing you already have a group in your LDAP, you can the group to your sudoers file.
Check to see if sssd has imported the groups from your ldap:
~$ getent group
Once you see the group name with the users you want to add, just edit the sudoers file
~$ visudo
Make sure you add it like so:
## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment) #includedir /etc/sudoers.d %new_sudoer_group ALL = (ALL) ALL
Add Service to auto start on boot
list current state
~$ sudo chkconfig --list <service name; ie. mysqld>
set service to start on boot
~$ sudo chkconfig --level 345 <service name; ie. mysqld> on
Common packages to install on fresh (minimal) install
~$ sudo yum install telnet net-tools vim tcpdump bind-utils redhat-lsb-core wget-y
