Adjusting the configuration in the registry
As soon as you have completed the configuration, click "OK" and restart the device. You should always use the graphic interface just mentioned. If you wish to additionally adjust the configuration of the RAS Server, there are various ways open to you via the Windows registry on your CE device.
- Open the "Start menu " and click "Run"
- Enter "regedit" and confirm with "OK". The Registry Editor opens.
- Navigate to the key "HKEY_LOCAL_MACHINE\Comm\ppp\Server\Parms". You can set further parameters for the RAS Server here. Please note that the "ppp" key only exists after the RAS Server has been activated!
The table below shows you the different parameters in this key:
Attributes | Type | Default value | Explanation |
|---|---|---|---|
Enable | DWORD | 0x00000000 | Deactivates (0) or activates (1) the RAS Server |
StartupDelaySeconds | DWORD | 0x00000000 | Specifies the time delay after booting before the RAS Server is started. |
UseDHCPAddresses | DWORD | 0x00000000 | Deactivates (0) or activates (1) the use of DHCP addresses by clients. Can be used if the CE device contains an internal DHCP Server. |
UseAutoIpAddresses | DWORD | 0x00000000 | See explanation above |
AutoIpSubnet | DWORD | 0xC0A80000 | Subnet IP for AutoIP configuration. The calculation of the hexadecimal value to be entered here is explained further below. |
AutoIpSubnetMask | DWORD | 0xFFFF0000 | Subnet mask for AutoIP configuration. The calculation of the hexadecimal value to be entered here is explained further below. |
StaticIpAddrStart | DWORD | 0xC0A8FE01 | First IP address for static configuration. The calculation of the hexadecimal value to be entered here is explained further below. |
StaticIpAddrCount | DWORD | 0x000000FE | Number of IP addresses to be issued for static configuration. |
AuthenticationMethods | DWORD | 0x00400000 | Explained in detail further below. |
Flags | DWORD | 0x00000000 | Explained in detail further below. |
The value of each IP parameter is easy to determine through the binary and hexadecimal representation of an IP address. An IP address consists of 4 values, where each value corresponds to one byte (or 8 bits). The hexadecimal representation of an IP address can therefore be derived directly from the binary representation by directly converting every 4 bits into a hex number, for example:
IP address: | 192.168.0.1 |
Binary: | 11000000.10101000.00000000.00000001 |
Hexadecimal: | C0.A8.00.010xC0A80001 |
The following table shows some examples of subnet IPs, such as can be specified, for example, in the "AutoIpSubnet" parameter:
Subnet IP | Subnet Mask | Value IP (Hex) | Value Mask (Hex) |
|---|---|---|---|
192.168.0.0 | 255.255.255.0 | 0xC0A80000 | 0xFFFFFF00 |
192.168.1.0 | 255.255.255.0 | 0xC0A80100 | 0xFFFFFF00 |
192.168.2.0 | 255.255.255.0 | 0xC0A80200 | 0xFFFFFF00 |
172.16.0.0 | 255.255.0.0 | 0xAC100000 | 0xFFFF0000 |
The "AuthenticationMethods" parameter configures the RAS Server for the use of various protocols for client authentication. Please note that the protocols configured here are those that are rejected by the server! This means that, if a client attempts to establish a connection to the RAS Server via a rejected protocol, the connection attempt will be rejected by the server.
Protocol | Value (Hex) | Information |
|---|---|---|
PAP | 0x00040000 | The password is transmitted in plain text for authentication. Insecure! |
CHAP | 0x00080000 | Uses a random value together with the password to generate a one-way hash that is transmitted for the authentication. |
MS-CHAP | 0x00100000 | Microsoft's implementation of CHAP. Features some improvements over standard CHAP. |
MS-CHAP v2 | 0x00200000 | Version 2 of MS-CHAP. Supports mutual authentication of the communication devices for the first time. |
EAP | 0x00400000 | Developed from IETF. Supports various authentication mechanisms, such as RADIUS, certificates, etc. . However, this also means that additional software is required on the CE device, depending on the Authentication method. |
In order to block more than one protocol on the server side, the values made available in the above table must be interpreted as a bit mask in which the values are added together bit-wise. Example:
Protocols to be rejected: | PAP, CHAP, MS-CHAP |
Binary representation of PAP value: | 0000 0000 0000 0100 0000 0000 0000 0000 |
Binary representation of CHAP value: | 0000 0000 0000 1000 0000 0000 0000 0000 |
Binary representation of MS-CHAP value: | 0000 0000 0001 0000 0000 0000 0000 0000 |
Added together: | 0000 0000 0001 1100 0000 0000 0000 0000 |
Hex value to be configured: | 0x001C0000 |
The "Flags" parameter specifies the use of various further RAS features, which are listed in the following table. These features can be combined with one another by means of the above bit-wise addition.
Feature | Value (Hex) | Information |
|---|---|---|
Data Encryption | 0x01 | Requires data encryption, if set |
Unauthenticated Access | 0x02 | Allows unauthenticated access, if set |
Use of VJ header compression | 0x04 | Prevents the use, if set |
Use data compression | 0x08 | Prevents the use, if set |