One of the network functions of Android is VPN.VPN is an abbreviation of "Virtual Private Network". Simply put, use the Internet to create a route that is not eavesdropped by others, such as a "dedicated line".By using this, it is possible to connect directly to the network of the company or home even when connected to the Internet.
However, since this function is used in pair with the "VPN server", the VPN server must be operated on the network of the connection.VPNs have several methods, and there are differences in the available methods and encryption methods depending on the VPN server, and the settings on the android side must be adjusted to this.For home use, if you set up a server yourself, it is OK, but at the company, etc., you will need to connect to a existing VPN server.At this time, the VPN method of the company's VPN server and the settings on the Android side must be the same.
In addition, because it is generally used in a broadband router at home, packets are not transferred from the Internet side to the VPN server.For this purpose, it is necessary to transfer packets to VPN servers (running machines) using a function called "Port Mapping" or "Port Forward" in the router.
In the case of Android, some apps are required to use VPN and use networks such as home or company.If you only use the HTTP server (so -called web server) installed at home or company, you can use a web browser such as Chrome, but prepare some apps to access Windows networks and FTP servers.In Windows, etc., it is equipped with network clients as standard, so you can easily access your home or company file server, but please note that Android is not.
Another usage of VPN is that you connect to your home or company via VPN and use the Internet from there.For example, if you use the Internet in a country where overseas Internet services are restricted (at least in Japan is different) or in the region, connect to a home or company that will be a overseas site via VPN.You can also access the Internet from there.With Android, you can use such VPNs.
This allows you to access the restricted Internet sites, but depending on the country or region, it may be illegal or illegal, and if the connection destination is a home or company, you can see it.You need to be careful because it is an act with a "risk" because you can understand it.
VPN server method
This is a slightly complicated VPN connection, but this time, I will first explain from the basics.That said, this is not an Android, so it's easy.
Assume that your home machine is Windows.If you use Linux, it is not difficult to move the VPN server, and you probably have that kind of technology, so I will omit the explanation this time.
The following method is available for Android VPN.Conversely, in other VPN methods, Android VPN cannot be set.
There are similar words.Each has the following meaning.
| PPTP | マイクロソフトのトンネリングプロトコル(複数の暗号化方式あり) |
|---|---|
| L2TP | シスコ社のL2FとPPTPを組み合わせたトンネリングプロトコル(暗号化なし) |
| IPsec | 暗号化IP通信(L2TPと組み合わせて利用) |
| PSK | Pre Share Key(事前共有鍵) |
| RSA | RAS電子証明書を使う公開鍵暗号方式 |
| Xauth | IPsecと組み合わせるユーザー認証方式 |
| Hybrid | IPsecと組み合わせる認証方式 |
Tunneling protocol is a method of putting a packet in a packet of another protocol and transferring it.In other words, put the packet in the packet, transfer it to a specific address, solve it on the destination address side and take out the original packet.By doing this, you can transfer packets sent by applications that are operating on the transfer source.It is a well -known mechanism with VPN, but in general, when it is called "tunneling protocol", it is not an encryption or the like, and it is assumed that it is combined with other encryption protocols.In the case of L2TP, it assumes a combination with IPsec.The PPTP has a Microsoft's unique encryption method (can be set without encryption).
Xauth and Hybrid are "authentication" methods combined with IPsec.IPsec can encrypt packets, but do not have functions such as user authentication at the connection destination as a protocol.Therefore, it is necessary to combine it with other authentication protocols.They are XAuth and Hybrid.
PSK and RSA are used for authentication, PSK sets the same key (string) between the transfer source and the destination, and RSA is a method that uses Ras certificates.
In the RAS method, it is generally for companies because the issuance of a certificate is costly.Use PSK when using it individually.
VPN registers the profile with "Settings" ⇒ "Wireless and Network" ⇒ "Others" ⇒ "VPN" and connect.In the profile, parameters such as VPN connection destinations are stored and multiple can be created. | These six types of VPN connection methods supported by Android 4.4.2.If the VPN server does not support any one of these, VPN connection cannot be made from an Android. |
If you need a router settings
In order to access your home or company network from the Internet, you need to set a port -forward (also called port mapping) or set a packet filter with a router connected to the Internet. In other words, in the router settings, the VPN server allows the connection to the ports waiting. This function is called "portfooding" or "port mapping", and the name and setting method are different depending on the manufacturer and model of the router, but the principle is the same type of packet that came to a specific port number. Is a function to transfer to a specific IP address in the local network. For this reason, in general, "destination IP address", "protocol (number)", and "port number" are set. Depending on the model, there are differences, such as setting the same IP address to multiple continuous ports, and even the same destination needs to be set one by one for each port number, but the above three information. Set at least. If you don't know this, you have to call the manufacturer's support if you don't know. In some cases, it may be necessary to switch to the setting method such as expert mode and detailed setting instead of simple settings.
To select a VPN server, you must select one that corresponds to one of the Android VPN methods.For companies, there are products, and there are routers and dedicated hardware with these functions.You can also build a VPN server by using Microsoft server products such as Windows Server.
In the case of individuals, it is high to buy Windows Server, so you have to use a free VPN server.That's why next time, we plan to explain the free VPN server that can be easily installed on the Windows client machine.
