netsh interface ip set address [Connection Name] [Source] [IP] [Netmask] [Gateway] [Metric]

• [Connection Name] is the connection name which the network adapter is assigned to. You can see the name in the Control Panel Network Connections panel or by using the ipconfig /all command from the command prompt.
• [Source] is the source of IP address, whether it is static or dhcp. If you set to dhcp. You can ignore all other remaining parameter.
• [IP] is the IP address you set.
• [Netmask] is the network mask for the IP address.
• [Gateway] is the the gateway IP address.
• [Metric] is the metric for the gateway.

for example:

netsh interface ip set address "Local Area Connection" static 192.168.1.10 255.255.255.0 192.168.1.1 1

The above command will set your “Local Area Connection” network adapter IP to static IP 192.168.1.10 with netmask 255.255.255.0, gateway 192.168.1.1, and gateway metric 1.

To set DNS server for the network connection use the following command:

netsh interface ip set dns "Local Area Connection" static 202.134.1.10

To add a second DNS server, use the following command:

netsh interface ip add dns "Local Area Connection" 202.134.0.155 index=2

OK, have a good try.

Here’s a step by step guide to make things work:

1. Start the Cellular Emulator by Clicking Start | All Programs | Windows Mobile 6 SDK | Tools | Cellular Emulator.
2. Notice at the bottom left corner status bar of the Cellular Emulator window, that is the COM port which is being used by the Cellular Emulator. Mine is COM3, but yours may be different port.
   
3. Start the Windows Mobile 6 Professional Emulator from within Microsoft Visual Studio 2005. You can start the by debugging (pressing F5) your currently developed mobile application. Or Clicking Tools | Device Emulator Manager… . Then select Windows Mobile 6 Professional Emulator from the Device Emulator Manager dialog box. Right click on it and then choose Connect. It will launch the WIndows Mobile 6 Professional Emulator.
   
4. In the Windows Mobile 6 Professional Emulator click File | Configure…
5. Select Peripherals tab on Emulator Properties dialog window.
6. Under the Serial Port 0 there is a combo box which only have one (Do not map) option. Here is the tricky part: type in the COM port specified by the Cellular Emulator on the combo box, in this case: COM3 and then click OK.
   
7. The configuration process is now complete but the Windows Mobile 6 Professional Emulator is not yet connected to the Cellular Emulator. The last essential step is restarting the Windows Mobile 6 Professional Emulator by choosing File | Reset | Soft, and then click Yes.

That’s it! Now you can have your Windows Mobile 6 Professional Emulator “talk” to the Cellular Emulator. Try to make a call and/or sending SMS from the device emulator and the Cellular Emulator.

This tutorial is adapted with a little modifications from Wei Meng Lee’s blog.

It is possible to do with a method called ARP redirect or sometimes it is called ARP poisoning. This method is also often used by worms or spyware to hijack your private information gathered by those worms or spyware and sending ’silently’ through internet to it’s owner without you to be noticed. This is can be avoided by installing antivirus or anti-spyware that monitor and scan your network packet data activity on your network connections.

In computer networking, the Address Resolution Protocol (ARP) is the method for finding a host’s hardware address when only its Network Layer address is known (wikipedia). It means after your computer is finding a host’s IP address, it can resolve that host hardware address (MAC Address) using ARP.

For example, my computer connected to the internet through gateway 192.168.1.1. After pinging an IP 192.168.1.1, my computer will resolve it’s MAC address 00-19-21-67-f5-b7. In Windows the ARP table that my computer use can be shown by using the arp command in command prompt:

C:\Documents and Settings\Aryo>arp -a

Interface: 192.168.1.2 --- 0x2
  Internet Address      Physical Address      Type
  192.168.1.1           00-19-21-67-f5-b7     dynamic

From the above example, 00-19-21-67-f5-b7 is MAC Address of 192.168.1.1 host. It was dynamically generated after we ping the host. So any data send through 192.168.1.1 will be sent to host which MAC Address is 00-19-21-67-f5-b7.

If someone or something or your network is sniffing or ARP poisoning your packet data, it will inject an ARP data to your computer ARP table. For example, after my computer is ‘poisoned’ by 192.168.1.9 host (the sniffer), my computer ARP table will become like this:

C:\Documents and Settings\Aryo>arp -a

Interface: 192.168.1.2 --- 0x2
  Internet Address      Physical Address      Type
  192.168.1.1           00-14-38-13-2a-f0     dynamic
  192.168.1.9           00-14-38-13-2a-f0     dynamic

From the above example, all of my packet data sent to IP address 192.168.1.1 will (also) be sent to 192.168.1.9 because in my ARP table, the host of IP 192.168.1.1 has hardware address 00-14-38-13-2a-f0 which is the hardware address of IP 192.168.1.9.

It means, if I send data to 192.168.1.1 the real sending is to 192.168.1.9 host. If the 192.168.1.9 host is also forwarding my sent data to and from the real gateway 192.168.1.1, I may not realize that my network connection is being redirected to 192.168.1.9 without seeing my ARP table.

Connection before poisoning:

My computer    <------------------>   Gateway
IP       192.168.1.2                  IP       192.168.1.1
Netmask  255.255.255.0                Netmask  255.255.255.0
MAC      00-19-D2-5C-C7-6A            MAC      00-19-21-67-f5-b7

If it is only my computer is poisoned and not the gateway, it become:

My computer    ---------->   Sniffer   --------------->   Gateway
     <--------------------------------------------------------
IP       192.168.1.2         IP       192.168.1.2         IP       192.168.1.1
Netmask  255.255.255.0       Netmask  255.255.255.0       Netmask  255.255.255.0
MAC      00-19-D2-5C-C7-6A   MAC      00-14-38-13-2a-f0   MAC      00-19-21-67-f5-b7

It is called half-routing ARP poisoning. The sniffer only can read data sent from my computer to gateway and not the reverse way. If the gateway is also ARP poisoned, it become:

My computer    <--------->   Sniffer   <-------------->   Gateway
IP       192.168.1.2         IP       192.168.1.2         IP       192.168.1.1
Netmask  255.255.255.0       Netmask  255.255.255.0       Netmask  255.255.255.0
MAC      00-19-D2-5C-C7-6A   MAC      00-14-38-13-2a-f0   MAC      00-19-21-67-f5-b7

It is called full-routing ARP poisoning. The sniffer can also read the data sent from gateway to my computer and vice versa. What if the data sent to gateway is your private and unencrypted data? That’s could be a disaster!

If you suspect this or if you see duplicated MAC Address with different IP in ARP table, you can set a static ARP table for the gateway by using arp command. The following is an example to create a static ARP table on your computer. First, clear all ARP data entry by using the command:

C:\Documents and Settings\Aryo>arp -d

And then create a static ARP entry to the gateway by using the following command:

C:\Documents and Settings\Aryo>arp -s 192.168.1.1 00-19-21-67-f5-b7

Now the ARP entry for the gateway will become a static entry.

C:\Documents and Settings\Aryo>arp -a

Interface: 192.168.1.2 --- 0x2
  Internet Address      Physical Address      Type
  192.168.1.1           00-19-21-67-f5-b7     static
  192.168.1.111         00-11-22-33-44-55     dynamic

Well, hope this article helps. Any comments or corrections are welcome.

You can test a port whether it is live or not by telneting the port using the telnet command. The telnet command is a utility to connect over TCP and defaults to port 25 23 (make a TCP connection to port 25 23 on remote computer/server). But if you specify a different port than 25 23, then what the telnet command do is opening a TCP connection on the specified port to the remote computer/server.

For example (in Windows):

C:\> telnet 192.168.1.1 80

In above example, the telnet command is trying to open HTTP connection (port 80) to the 192.168.1.1 host computer rather than opening the default telnet port (port 25 23).

If the above connection is unsuccessful, then you will get this message:

C:\>telnet 192.168.1.1 80
Connecting To 192.168.1.1...Could not open connection to the host, on port 80: Connect failed

Otherwise, you will prompted to enter another input/arguments for a service of the specified port.

If you dealing with firewall, typically it blocks TCP/UDP connection in a direction or both direction on specified port. So firewall didn’t deal with “telnet protocol” rather than TCP/UDP connections on specified ports.

For example, a firewall on destination host is blocking TCP connection on port 25 23 (the default telnet protocol port) and not for the other ports. You are telnetting on port 80, your telnet command will be successful, and you will also knew that TCP port 80 on destination host is open.

Koneksi internet dibagi dengan sebuah hub, yang memiliki keterbatasan jumlah port yang digunakan oleh beberapa PC (baca: laptop) dengan sistem operasi (yang pada umumnya adalah) Microsoft Windows. Lalu bagaimana caranya membagi kembali koneksi internet tersebut agar dapat digunakan oleh lebih banyak PC lagi tanpa membeli sebuah hub atau router tambahan?

Salah satu caranya adalah dengan menjadikan salah satu PC yang terhubung dengan hub tersebut menjadi sebuah gateway (router) untuk PC tambahan lainnya. Syaratnya PC tersebut memiliki 2 buah network interface (a.k.a LAN card) yang umumnya biasa ditemukan di laptop-laptop modern saat ini. Yaitu Ethernet Card dan WiFi card.

Microsoft Windows bisa jadi router? Perlu install software apa?

Bisa, untuk routing statik biasa, bahkan tanpa perlu meng-install software tambahan apapun. Bagaimana bisa? OS Microsoft Windows memiliki sebuah command route, untuk memanipulasi routing. command inilah yang dimanfaatkan untuk membuat sebuah Windows Router.

Dari contoh kasus ini, PC yang dijadikan router memiliki konfigurasi IP

• Ethernet: 192.168.1.220/24
• WiFi: 192.168.0.1/24

Dari sini bisa dilihat bahwa network ID untuk Ethernet dan WiFi berbeda. Network ID WiFi inilah yang digunakan oleh PC tambahan untuk mengakses network ID Ethernet. Agar Network ID 192.168.0.x dapat mengakses Network ID 192.168.1.x, PC router perlu menambahkan route entry di routing table-nya.

Routing table bisa dilihat dengan menggunakan command route print, contohnya:

C:\Users\VISTA>route print
===========================================================================
Interface List
9 ...00 16 d4 8f 6a a5 ...... Realtek RTL8101E Family PCI-E Fast Ethernet
8 ...00 19 d2 5c c7 6a ...... Intel(R) PRO/Wireless 3945ABG Network Conne
1 ........................... Software Loopback Interface 1
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination  Netmask          Gateway         Interface      Metric
0.0.0.0              0.0.0.0          192.168.1.1     192.168.1.220  21
127.0.0.0            255.0.0.0        On-link         127.0.0.1      306
127.0.0.1            255.255.255.255  On-link         127.0.0.1      306
127.255.255.255      255.255.255.255  On-link         127.0.0.1      306
169.254.0.0          255.255.0.0      On-link         192.168.1.220  30
169.254.255.255      255.255.255.255  On-link         192.168.1.220  276
192.168.0.0          255.255.255.0    On-link         192.168.0.1    281
192.168.0.1          255.255.255.255  On-link         192.168.0.1    281
192.168.0.255        255.255.255.255  On-link         192.168.0.1    281
192.168.1.0          255.255.255.0    On-link         192.168.1.220  276
192.168.1.220        255.255.255.255  On-link         192.168.1.220  276
192.168.1.255        255.255.255.255  On-link         192.168.1.220  276
224.0.0.0            240.0.0.0        On-link         127.0.0.1      306
224.0.0.0            240.0.0.0        On-link         192.168.1.220  276
224.0.0.0            240.0.0.0        On-link         192.168.0.1    281
255.255.255.255      255.255.255.255  On-link         127.0.0.1      306
255.255.255.255      255.255.255.255  On-link         192.168.1.220  276
255.255.255.255      255.255.255.255  On-link         192.168.0.1    281
===========================================================================
Persistent Routes:
Network Address      Netmask          Gateway         Address        Metric
0.0.0.0              0.0.0.0          192.168.1.1     Default
===========================================================================

Dari sini dapat dilihat bahwa Ethernet card memiliki ID 9 di daftar Interface List-nya dan WiFi card memiliki Interface ID 8. Dari sini perlu menambahkan 2 route: dari Network ID 192.168.0.x/24 ke Network ID 192.168.1.x/24 dan sebaliknya.

Command-nya:

> route add 0.0.0.0 mask 0.0.0.0 192.168.1.220 if 8
> route add 192.168.0.0 mask 255.255.255.0 192.168.0.1 if 9

Sehingga jika dilihat pada routing table-nya akan menjadi:

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination  Netmask          Gateway         Interface      Metric
0.0.0.0              0.0.0.0          192.168.1.1     192.168.1.220  21
0.0.0.0              0.0.0.0          192.168.1.220   192.168.0.1    26
127.0.0.0            255.0.0.0        On-link         127.0.0.1      306
127.0.0.1            255.255.255.255  On-link         127.0.0.1      306
127.255.255.255      255.255.255.255  On-link         127.0.0.1      306
169.254.0.0          255.255.0.0      On-link         192.168.1.220  30
169.254.255.255      255.255.255.255  On-link         192.168.1.220  276
192.168.0.0          255.255.255.0    192.168.0.1     192.168.1.220  21
192.168.0.0          255.255.255.0    On-link         192.168.0.1    281
192.168.0.1          255.255.255.255  On-link         192.168.0.1    281
192.168.0.255        255.255.255.255  On-link         192.168.0.1    281
192.168.1.0          255.255.255.0    On-link         192.168.1.220  276
192.168.1.220        255.255.255.255  On-link         192.168.1.220  276
192.168.1.255        255.255.255.255  On-link         192.168.1.220  276
224.0.0.0            240.0.0.0        On-link         127.0.0.1      306
224.0.0.0            240.0.0.0        On-link         192.168.1.220  276
224.0.0.0            240.0.0.0        On-link         192.168.0.1    281
255.255.255.255      255.255.255.255  On-link         127.0.0.1      306
255.255.255.255      255.255.255.255  On-link         192.168.1.220  276
255.255.255.255      255.255.255.255  On-link         192.168.0.1    281
===========================================================================

PC tambahan yang akan mengakses internet harus menjadikan PC Router (192.168.1.220) sebagai gateway-nya dan menjadikan PC Router tersebut sebagai DNS Server-nya.

PC tambahan yang akan menggunakan internet, harus menghubungkan WiFi-nya ke PC Router dengan metode ad-hoc dan menggunakan IP Address 192.168.1.x/24, dimana x = 1-254 sesuai dengan Network ID WiFi PC Router.

Manipulates network routing tables.

ROUTE [-f] [-p] [-4|-6] command [destination] [MASK netmask] [gateway] [METRIC metric] [IF interface]

-f Clears the routing tables of all gateway entries. If this is
used in conjunction with one of the commands, the tables are
cleared prior to running the command.

-p When used with the ADD command, makes a route persistent across
boots of the system. By default, routes are not preserved
when the system is restarted. Ignored for all other commands,
which always affect the appropriate persistent routes. This
option is not supported in Windows 95.

-4 Force using IPv4.

-6 Force using IPv6.

command One of these:

PRINT Prints a route
ADD Adds a route
DELETE Deletes a route
CHANGE Modifies an existing route
destination Specifies the host.
MASK Specifies that the next parameter is the ‘netmask’ value.
netmask Specifies a subnet mask value for this route entry.
If not specified, it defaults to 255.255.255.255.
gateway Specifies gateway.
interface the interface number for the specified route.
METRIC specifies the metric, ie. cost for the destination.

All symbolic names used for destination are looked up in the network database
file NETWORKS. The symbolic names for gateway are looked up in the host name
database file HOSTS.

If the command is PRINT or DELETE. Destination or gateway can be a wildcard,
(wildcard is specified as a star ‘*’), or the gateway argument may be omitted.

If Dest contains a * or ?, it is treated as a shell pattern, and only
matching destination routes are printed. The ‘*’ matches any string,
and ‘?’ matches any one char.

Examples:

157.*.1, 157.*, 127.*, *224*.

Pattern match is only allowed in PRINT command.

Diagnostic Notes:
Invalid MASK generates an error, that is when (DEST & MASK) != DEST.

Example:

> route ADD 157.0.0.0 MASK 155.0.0.0 157.55.80.1 IF 1
  The route addition failed: The specified mask parameter is invalid.
  (Destination & Mask) != Destination.

Examples:

> route PRINT
> route PRINT -4
> route PRINT -6
> route PRINT 157* .... Only prints those matching 157*
> route ADD 157.0.0.0 MASK 255.0.0.0 157.55.80.1 METRIC 3 IF 2
  destination^             ^mask     ^gateway     metric^    ^Interface

If IF is not given, it tries to find the best interface for a given
gateway.

> route ADD 3ffe::/32 3ffe::1
> route CHANGE 157.0.0.0 MASK 255.0.0.0 157.55.80.5 METRIC 2 IF 2

CHANGE is used to modify gateway and/or metric only.

> route DELETE 157.0.0.0
> route DELETE 3ffe::/32