Revision as of 09:50, 30 October 2014

Routing & NAT

Configuring NAT (Sharing Internet)

Start Routing

For this, we do not need to install anything new. Everything is right there but is currently disabled.

First, edit sysctl.conf

nano /etc/sysctl.conf

Find this:

net.ipv4.ip_forward=1

Uncomment it by removing the #. Now forwarding is enabled in the system kernel.

Start routing without a reboot

This will enable it without a reboot. Like restart a service

echo 1 > /proc/sys/net/ipv4/ip_forward

NAT

This make a NAT rule for post-routing. It sets the eth0 as the output card (The one out to the internet) and sets source to it's own IP through MASQUERADE

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Save the iptable so it can be loaded correctly after a reboot/shutdown

iptables-save > /etc/iptables.rules

Load the iptables.rules at startup

Edit the file interfaces

sudo nano /etc/network/interfaces

Insert these lines to the eth0 interface

pre-up iptables-restore < /etc/iptables.rules
post-down iptables-restore < /etc/iptables.rules

Like this

# The extended interfaces
auto eth0
iface eth0 inet dhcp
pre-up iptables-restore < /etc/iptables.rules
post-down iptables-restore < /etc/iptables.rules

Test it out on your other client.

NIS

Enter the hosts.allow file

sudo nano /etc/hosts.allow

Add the following line

portmap ypserv ypbind: 10.0.0.0/255.255.255.0

Install NIS. You will be prompted for domain name. The domain name is not the DNS-domain name - but a unique name for the nodes and master that share the same information.

• NOTE: It is recommended you install NIS using the VMware console instead of SSH

sudo apt-get install portmap nis

Enter the nis file

sudo nano /etc/default/nis

Set the NISSERVER line to

NISSERVER=master

Enter the yp.conf file

sudo nano /etc/yp.conf

Add the line

domain dka.local server 127.0.0.1

Enter the ypserv.securenets file

nano /etc/ypserv.securenets

Replace the 0.0.0.0 line with the 255.255.255.0 10.0.0.0

0.0.0.0         0.0.0.0

255.255.255.0         10.0.0.0

Reboot the Yellowpages service so the new configuration can be loaded

service ypserv restart

Adding a user

Efter du har oprettet en ny bruger, adduser er det nødvendigt at genopbygge nis maps!

root@head:~# <input>make -C /var/yp</input>
make: Går til katalog '/var/yp'
make[1]: Går til katalog '/var/yp/c1.local'
Updating passwd.byname...
Updating passwd.byuid...
Updating netid.byname...
Updating shadow.byname...
make[1]: Forlader katalog '/var/yp/c1.local'
make: Forlader katalog '/var/yp'

Script adding user in a Cluster

The following simple script:

• Add a user on the NIS server.
• Add a ssh key to the users /home library.
  • In this cluster /home is distributed with NFS to all nodes. Logon to nodes without entering password
• Rebuilding the NIS database with the new user

#!/bin/bash
echo -e "Adding user to cluster\n"
echo -en "User login name: "
read NAME
adduser $NAME

echo -e "Creating keys"
su $NAME -c "ssh-keygen"
echo -e "Distributing keys"
su $NAME -c "cat /home/$NAME/.ssh/id_rsa.pub >> /home/$NAME/.ssh/authorized_key$
echo -e "Rebuild NIS database"
make -C /var/yp