My garage

Pertama yang harus di lakukan adalah mensetting mgw(main gateway) supaya bisa connect ke internet
Sebelum Mensetting :

1.IP public lengkap dengan netmask,broadcast dan dns nya misalnya :

RANGE : 202.159.121.0/29
IP : 202.159.121.2
GATEWAY : 202.159.121.1
Nemast : 255.255.255.248
broadcast : 202.159.121.7

DNS1 : 202.159.0.10
DNS2 : 202.159.0.20

berarti kita mendapatkan ip 5 buah dari 202.159.121.2 - 202.159.121.6

2.Menentukan IP local yang akan kita gunakan buat client Setting IP MGW :
#.[demank@sm-bireuen]# vi /etc/sysconfig/network

lalu isi dengan :
NETWORKING =yes
HOSTNAME =mgw.domain.com
GATEWAY =202.159.121.1

lalu saya simpan dengan menekan :wq

2.Menconfigurasi IP eth0(default)
[demank@sm-bireuen]# vi /etc/sysconfig/network-scripts/ifcfg-eth0

lalu isi dengan :
DEVICE =eth0
BOOTPROTO =static
IPADDR =202.159.121.2
BROADCAST =202.159.121.7
NETMASK =255.255.255.249
ONBOOT =yes
USERCTL =no

lalu simpan dengan menekan :wq

3.Setting dns resolve
[demank@sm-bireuen]# vi /etc/resolv.conf

lalu isi dengan nameserver dari isp kita tadi :

nameserver 202.159.0.10
nameserver 202.159.0.20

lalu simpan dengan menekan :wq

4.Setting ip_forwarding
[demank@sm-bireuen]# vi /etc/sysctl.conf

rubah net.ipv4.ip_forward = 0 menjadi net.ipv4.ip_forward = 1
atau kalau gak ada net.ipv4.ip_forward = 0 tambahin net.ipv4.ip_forward = 1

simpen dengan menekan :wq

5.restart network
[demank@sm-bireuen]#/etc/init.d/network restart

Shutting down interface eth0: [ OK ]
Shutting down loopback interface: [ OK ]
Disabling IPv4 packet forwarding: [ OK ]
Setting network parameters: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: [ OK ]

[demank@sm-bireuen]#chkconfig –level 2345 network on
[demank@sm-bireuen]#

6.testing dengan ping ke default gateway 202.159.121.1
[demank@sm-bireuen]#ping 202.159.121.1

PING 202.159.121.1 (202.159.121.1) 56(84) bytes of data.

64 bytes from 202.159.121.1: icmp_seq=1 ttl=63 time=0.356 ms
64 bytes from 202.159.121.1: icmp_seq=2 ttl=63 time=0.269 ms
64 bytes from 202.159.121.1: icmp_seq=3 ttl=63 time=0.267 ms
64 bytes from 202.159.121.1: icmp_seq=4 ttl=63 time=0.268 ms

— 202.159.121.1 ping statistics —

4 packets transmitted, 4 received, 0% packet loss, time 2997ms

rtt min/avg/max/mdev = 0.267/0.290/0.356/0.038 ms

7.test ping google.com untuk ngecek dns nya kalau muncul :
PING google.com (216.239.39.99) 56(84) bytes of data.berarti dns kita untuk mgw dah bekerja, tapi kalau muncul :ping: unknown host google.com berarti dns yang kita isikan di /etc/resolve.conf masih salah,silahkan cek lagi ke ISP nya nah bereskan sudah setting IP untuk mgw nya supaya mgw ini bisa sekaligus di gunakan sebagai ns server oleh client maka harus di install daemon bind atau
daemon nameserver yang lain atau kalau sudah ada tinggal hidupkan Bind nya

[demank@sm-bireuen]#etc/init.d/named restart

Stopping named: [ OK ]
Starting named: [ OK ]

[demank@sm-bireuen]#chkconfig –level 2345 named on
[demank@sm-bireuen]#

misalnya ip ke client adalah :
192.168.0.1/24
IP : 192.168.0.1
netmask : 255.255.255.0
broadcast : 192.168.0.255
RANGE IP CLIENT : 192.168.0.2-192.168.0.254

Setting ip untuk eth1 (yang ke client)

1.memberi IP 192.168.0.1 di eth1
[demank@sm-bireuen]# vi /etc/sysconfig/network-scripts/ifcfg-eth1

lalu isi dengan :
DEVICE=eth1
BOOTPROTO=static
IPADDR=192.168.0.1
NETMASK=255.255.255.0
BROADCAST=192.168.0.255
ONBOOT=yes
USERCTL=no

lalu simpan dengan menekan :wq

2.Restart networknya
[demank@sm-bireuen]#/etc/init.d/network restart

Shutting down interface eth0: [ OK ]
Shutting down interface eth1: [ OK ]
Shutting down loopback interface: [ OK ]
Disabling IPv4 packet forwarding: [ OK ]
Setting network parameters: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: [ OK ]
Bringing up interface eth1: [ OK ]

3.Test dengan cara ping ip eth1
[demank@sm-bireuen]# ping 192.168.0.1

PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.

64 bytes from 192.168.0.1: icmp_seq=1 ttl=63 time=0.356 ms
64 bytes from 192.168.0.1: icmp_seq=2 ttl=63 time=0.269 ms
64 bytes from 192.168.0.1: icmp_seq=3 ttl=63 time=0.267 ms
64 bytes from 192.168.0.1: icmp_seq=4 ttl=63 time=0.268 ms

— 192.168.0.1 ping statistics —

4 packets transmitted, 4 received, 0% packet loss, time 2997ms

rtt min/avg/max/mdev = 0.267/0.290/0.356/0.038 ms

Tinggal Setting IP computer client dengan ketentuan di bawah ini :

IP : 192.168.0.2 - 192.168.0.254
GATEWAY : 192.168.0.1
NETMASK : 255.255.255.0
BROADCAST : 192.168.0.255
NAMESERVER : 192.168.0.1

misal :
Client01
===============================

IP : 192.168.0.2
GATEWAY : 192.168.0.1
NETMASK : 255.255.255.0
BROADCAST : 192.168.0.255
NAMESERVER : 192.168.0.1

Client02
===============================

IP : 192.168.0.3
GATEWAY : 192.168.0.1
NETMASK : 255.255.255.0
BROADCAST : 192.168.0.255
NAMESERVER : 192.168.0.1

dan seterusnya sesuai banyaknya client,yang berubah hanya IP untuk client windows maka setting IP di bagian Start Menu/Setting/Control Panel/Network setelah di setting ip client, maka coba ping ke 192.168.0.1 dari client,kalau berhasil berarti client dan MGW nya sudah tersambung.Setting MGW supaya client bisa internat dengan menggunakan NAT

1.Matikan iptablesnya
[demank@sm-bireuen]#/etc/init.d/iptables stop

Flushing all chains: [ OK ]
Removing user defined chains: [ OK ]
Resetting built-in chains to the default ACCEPT policy: [ OK ]

[demank@sm-bireuen]#

2.Tambahkan iptables untuk Source NAt sesuai dengan ip di eth0
[demank@sm-bireuen]# /sbin/iptables -t nat -A POSTROUTING

-o eth0 -s 192.168.0.0/24 -j SNAT –to-source 202.159.121.2

[demank@sm-bireuen]#/sbin/iptables-save > /etc/sysconfig/iptables
[demank@sm-bireuen]# /etc/init.d/iptables restart

Flushing all current rules and user defined chains: [ OK ]
Clearing all current rules and user defined chains: [ OK ]
Applying iptables firewall rules: [ OK ]

[demank@sm-bireuen]# iptables-save

SNAT sudah,SNAT disini standar sekali dan gak ada proteksi untuk mengetest nya kita browser di client lalau buka google.com,kalau jalan berati kita sudah berhasil

ip r del default; ip route add default via 172.20.6.2
ini untuk merubah default gateway