Initial Linux Setup

Create a local user account

Log in to the system as the root user, create a local user account, and assign a password to this local account.

useradd erodriguez -c "Enrique Rodriguez"
passwd erodriguez

Configure sudo

The sudo ("superuser do") utility allows an unprivileged (i.e. non-root) normal user to execute commands with root privileges. It is good practice to only run commands as the root user when absolutely necessary. By running root commands with the sudo utility, we are less likely to commit errors that could cripple the system than if we had a full root session.

In this example, my local user account is erodriguez. Substitute your local user account accordingly.

To configure sudo, run /usr/sbin/visudo and add the following at the bottom of the /etc/sudoers file:

erodriguez   ALL = NOPASSWD: ALL

Finding what RPM provides a tool

You must determine the full path to the tool, on a machine that already has the tool installed.

$ which dig
/usr/bin/dig

If you have the RPM installed, you can use:

$ rpm -qf /usr/bin/dig
bind-utils-9.3.3-0.1.rc3.fc6

If the RPM is not installed, you can use your repository tool, such as 'yum':

$ yum provides /usr/bin/dig 
...
bind-utils.i386                          30:9.3.2-41.fc6        core            
Matched from:
/usr/bin/dig

Now you can install the tool.

$ yum install bind-utils

Install the CentOS RPM signing key

It is not installed as part of the base system install for security reasons. This provides you the opportunity to validate the key before installing it on your system.

RPM has the capacity to retrieve the key from a Centos Mirror:

rpm --import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-4

YUM: Setup and Usage http://sial.org/howto/yum/ http://sial.org/howto/yum/yum-vhost.conf

Create a Local Yum Repository http://tqmcube.com/repo.php

How to run your own yum repository http://servers.linux.com/article.pl?sid=04/07/22/1718242

Allowing daily yum updates

# vi /etc/updatedb.conf
# To enable the updatedb in cron, set DAILY_UPDATE to yes
DAILY_UPDATE=no

yum install openldap-servers
openldap-servers, openldap, openldap-clients

yum grouplist
yum groupinstall

Disabling Linux Services

apmd

avahi-daemon
avahi-dns

bluetooth
hcid
hidd
sdpd

nfs
nfslock
portmap
rpcgssd
rpcidmapd
rpcsvcgssd

sendmail

Additional Resources

Services in Fedora Core 6 http://www.mjmwired.net/resources/mjm-services-fc6.html

Server Hardening

Dynamically Creating User Home Directories

If user home directories are going to be created locally then PAM will need to dynamically create a user home directory. The following configures PAM to create user home directories if they do not exist during the login process.

1. Open the /etc/pam.d/system-auth file and add the following line above the first session line:
session required /lib/security/pam_mkhomedir.so skel=/etc/skel umask=0022

#%PAM-1.0

# This is required for console ownership access
session optional /lib/security/pam_console.so
session required /lib/security/pam_mkhomedir.so skel=/etc/skel umask=0022
...