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Ubuntu – Internet Sharing

Posted on the January 25th, 2009 under linux by Irpus

Berikut cara sederhana apabila kita ingin sharing internet dari Ubuntu. Karena base linux, semua step dijalan kan dari CLI (command line interface) dan pada level root.

1. Pertama kali, pastikan sudah terinstall dengan benar interface tambahan di PC Ubuntu.
2. Tambahkan IP Address sesuai dengan keinginan kita, misal 192.168.0.1 netmask 255.255.255.0
3. Setting NAT (Network Address Transtalation) dari command line :

#iptables -t nat -A POSTROUTING -o ethX -j MASQUERADE

1. ethX, X adalah nomor interface ethernet yang akan kita gunakan untuk sharing.
2. Install dnsmasq dan ipmasq dengan apt-get :

# apt-get install dnsmasq ipmasq

1. Restart dnsmasq

# /etc/init.d/dnsmasq restart

1. onfigurasi ulang ipmasq

# dpkg-reconfigure ipmasq

1. Ulangi step 3
2. Reboot, apabila diperlukan.

Step ini sudah ditest dan dijalankan tepat beberapa menit sebelum ditulis. Berikut capture dari proses konfigurasi di PC Ubuntu saya :

root@irpus-nuX:/home/irpus# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0e:a6:45:aa:c7  (ni eth yang saya gunakan untuk sharing)
inet addr:192.168.0.1  Bcast:192.168.0.255  Mask:255.255.255.0
inet6 addr: fe80::20e:a6ff:fe45:aac7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1060 (1.0 KB)  TX bytes:1818 (1.7 KB)
Interrupt:16 Base address:0×8800

eth1      Link encap:Ethernet  HWaddr 00:60:97:a1:dd:b1
inet addr:192.168.6.4  Bcast:192.168.6.255  Mask:255.255.255.0
inet6 addr: fe80::260:97ff:fea1:ddb1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:5001 errors:0 dropped:0 overruns:0 frame:0
TX packets:3275 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3521422 (3.3 MB)  TX bytes:473335 (462.2 KB)
Interrupt:17 Base address:0×8400

lo        Link encap:Local Loopback
inet addr:127.0.0.1  Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING  MTU:16436  Metric:1
RX packets:2966 errors:0 dropped:0 overruns:0 frame:0
TX packets:2966 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:148300 (144.8 KB)  TX bytes:148300 (144.8 KB)

root@irpus-nuX:/home/irpus# ping 192.168.0.4 (test ping ke laptop)
PING 192.168.0.4 (192.168.0.4) 56(84) bytes of data.
64 bytes from 192.168.0.4: icmp_seq=1 ttl=128 time=2.34 ms
64 bytes from 192.168.0.4: icmp_seq=2 ttl=128 time=0.178 ms

— 192.168.0.4 ping statistics —
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.178/1.263/2.349/1.086 ms

root@irpus-nuX:/home/irpus# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
root@irpus-nuX:/home/irpus# apt-get install dnsmasq ipmasq
Reading package lists… Done
Building dependency tree
Reading state information… Done
The following extra packages will be installed:
dnsmasq-base
Suggested packages:
resolvconf midentd oidentd mc bridge-utils
The following NEW packages will be installed:
dnsmasq dnsmasq-base ipmasq
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 327kB of archives.
After this operation, 1360kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://kambing.ui.edu hardy/universe ipmasq 4.0.8-4ubuntu1 [81.1kB]
Get:2 http://kambing.ui.edu hardy/main dnsmasq-base 2.41-2ubuntu1 [233kB]
Get:3 http://kambing.ui.edu hardy/universe dnsmasq 2.41-2ubuntu1 [12.0kB]
Fetched 327kB in 31s (10.3kB/s)
Preconfiguring packages …
Selecting previously deselected package ipmasq.
(Reading database … 114649 files and directories currently installed.)
Unpacking ipmasq (from …/ipmasq_4.0.8-4ubuntu1_all.deb) …
Selecting previously deselected package dnsmasq-base.
Unpacking dnsmasq-base (from …/dnsmasq-base_2.41-2ubuntu1_i386.deb) …
Selecting previously deselected package dnsmasq.
Unpacking dnsmasq (from …/dnsmasq_2.41-2ubuntu1_all.deb) …
Setting up ipmasq (4.0.8-4ubuntu1) …

Setting up dnsmasq-base (2.41-2ubuntu1) …
Setting up dnsmasq (2.41-2ubuntu1) …
* Starting DNS forwarder and DHCP server dnsmasq                        [ OK ]

root@irpus-nuX:/home/irpus# /etc/init.d/dnsmasq restart
* Restarting DNS forwarder and DHCP server dnsmasq                      [ OK ]
root@irpus-nuX:/home/irpus# dpkg-reconfigure ipmasq
root@irpus-nuX:/home/irpus#