YOU ASK QUESTION
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	FAQ for ComSocks v2.6x
	FAQ for ComSocks v2.5

1. I can not view the whole page (with missing images), what can I do to fix this?
   


2. I can receive emails but I cann't send any out, what is the problem?
   


3. Why does my IE never dial a connection on the gateway after I have set Comtun to manage my dial-up?
   


4. When I install Comtun, I got an error complaining ws2_32.dll is missing. How to fix this problem?
   


5. Is Comtun/Comsocks compatible with Windows 2000 and Windows Millennium?
   


6. What is port 139 and how do I close it?
   


7. I am a little confused by the NAT function, so what do I need to do in order to enable it?
   


8. I want to use the DHCP daemon to simplify my local network setup, what do I need to do?
   


9. I'm using NAT and my ISP uses a proxy server. Can I still use the Remote Control?
   


10. How can I use Symphoy (Proxim) wireless cards with your software to share my modem by using peer to peer networking?
    


11. How can I use Comtun/Comsocks as a simple LAN firewall?
    
    
12. I try to install Comtun/Comsocks on Windows 2000, but the Linkbyte CKDriver does not appear on my protocols list. What do I do?
    
    
13. We'd like to restrict browser (HTTP?) access, but not email access to some users/PCs? how do we do that? do we use proxy instead of NAT?
    
    What's the use of the USERS tabbed folder on the Comtun/Comsocks Manager?
    
    
14. Can we run Comtun/Comsocks Proxy Server as a web server? How?
    
    
15. I want to configure all my clients to use the proxy cache module provided by Comtun/Comsocks, How can I use an automatic configuration script to automate my client host's proxy settings?
    
    
16. I want to run a web and/or ftp server on one of my internal system, how can I let users on the internet to access my server behind Comtun firewall?
    
    
17. I have a DirectPC satellite connection, but the client throughput is a bit of slow, how can i fix this problem?
    
    
18. I forget my login password, what am i going to do?
    
    
19. How do i configure the POP3 or SMTP daemon to filter my emails?
    
    
20. How do i tune a NT workstation to achieve a server-like performance?
    
    
21. How can I configure TCP/IP settings from the Command Prompt?
    
    

1. I can not view the whole page (with missing images), what can I do to fix this?
   This may happen in a ADSL connection using a PPPoE virtual adapter. It is because the MTU (Maximum Transmission Unit) value in the client host is not correct. Windows has a default value 1500 for Ethernet. However, many gateways or routers along the path from the proxy server to the destination host on the Internet may have a different MTU requirement. MTU is the maximum packet size in one TCP data frame. If this value is too large, the packet may be fragmented during the transmission or gets lost if the fragmentation is not allowed. To fix this, you can use a value 1492, 1490, 1460, or 576. When you test it, prefer to use a greater value first. Or just use 1400 as the MTU value if you don't bother.
   
   There are two ways to do the changes. The first and the easiest is to use a tool DRTCP (see Q17. only install on client hosts). Another is to edit the Windows registry manually for each windows workstation (again for clients only ). Here are the steps for the editting. I am assuming that you know how to use a registry editor "regedit.exe". You should be very cautious because a severe damage to your Windows can occur.
   
   (1) For Windows 95 clients, Add a DWORD value (Decimal) MaxMTU=1490 to the following key:
   
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\NetTrans\00yy
   (where yy ranges from 00 to 30, under those keys, you will see DriverDesc=TCP/IP)
   
   (2) For Windows 98 clients, Add a String value MaxMTU=1490 to the following key:
   
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\NetTrans\00yy
   (where yy ranges from 00 to 30, under those keys, you will see DriverDesc=TCP/IP)
   
   (3) For Windows NT clients, Add DWORD value (Decimal) MTU=1490 and RouterMTU (Decimal) =1490 to the following key:
   
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\<AdapterName>\Parameters\Tcpip
   (where AdapterName# indicates a Services subkey for a network adapter card, i.g. RTL80291)
   
   (4) For Windows 2000, Navigate down to the key: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<ID for Adapter>]
   Each ID Adapter has default keys for DNS, TCP/IP address, Default Gateway, subnet mask, etc. Find the key one that is for your network card. Create the following Entry:
   type=DWORD
   name="MTU" (Do NOT include the quotes)
   value (Decimal) =1490
   
   (5) For a Linux client, edit the "/etc/rc.d/rc.local" file and put the following at the END of the file:
   
   echo "Changing the MTU of ETH0"
   /sbin/ifconfig eth0 mtu 1490
   
   Replace "eth0" with the interface name that is the machine's upstream connection which is connected to the Internet.
   
   BTW, if this doesn't work, you can try other MTU values, e.g. 1460,1440, 576, etc...
   Please reboot your system after you change the MTU value.
   
   
2. I can receive emails but I cann't send any out, what is the problem?
   It could also be a MTU problem. see last question.
   
   
3. Why does my IE never dial a connection on the gateway after I have set Comtun to manage my dial-up?
   Comtun will overwrite your IE's settings for the dial-up connection on the gateway and make IE never dial a connection. By doing this way, Comtun can control the remote dialing from clients. If you want to recover the old way, please do not let Comtun to manage your dialing. Then set IE to use a dial-up connection. There is a way to work around this, you can enable HTTP daemon, then set the IE's proxy settings on the gateway to point to its local ip (i.e. 192.168.0.1). BTW, you need to enable dial-on-demand in Comtun. There is a screen shot in the How to -> Legacy Proxy Configuration in the help file about how to set the browser.
   
   
4. When I install Comtun, I got an error complaining ws2_32.dll is missing. How to fix this problem?
   You need to download a WinSock 2 Library update from Microsoft web site for your Windows 95. You should not install it over other Windows than Windows 95. Be warned that the Dialup Networking 1.2 (MS DUN) updates include a Winsock2 that is entirely insufficient, and the Winsock2 update must be reinstalled after installing Windows 95 dialup networking
   
   
5. Is Comtun compatible with Windows 2000 and Windows Millennium?
   Comtun/Comsocks v3.04/3.04a and above is compatible with Windows 2000. v3.05/3.05a is compatible with Windows 2000 and Millennium with certain restrictions(see the download page). v3.06/3.06a and above is fully compatible with windows 2000 and Millennium. Do not install older versions on the Windows Me (you can do so, but NAT function won't work). If you have experienced a port conflict in W2K, you can disable the system service causing the problem in the Service configuration in the control panel. Or you can modify the daemon listening port in Comtun. The possible conflict services would be DNS server, DHCP server, IIS (web service) server, FTP and Telnet server.
   
   
6. What is port 139 and how do I close it?
   Port 139 is used by various versions of Windows for file and printer sharing across a Windows network. Ideally, this will be disabled on your gateway computer for security reasons. To do so, simply open the Network settings in your gateway's control manager. Click on the button for File and Print Sharing. Here, you will see two check boxes for allowing others access to the gateway's files and printer. Remove the x from both of these options and click Ok to exit. After these are removed Windows will no longer monitor and respond on these ports, fixing this problem.
   
   
7. I am a little confused by the NAT function, so what do I need to do in order to enable it?
   NAT is called Network Address Translator. It attempts to provide a transparent routing to the local network. In short, by using NAT, you can configure each client host like the gateway host. You do not need to specify the proxy settings in each client (unless your ISP requires you to do so). Please do the following in order to run NAT:
   
   
   1. Your gateway should have two ethernet adapters or one dial-up adapter and one ethernet adapter.
   2. NAT should be marked on the Internet adapter with the Internet IP besides it on the gateway host (it may be the PPPoE virtual adapter if you are using DSL).
   3. Specify 192.168.0.1 as the ip address of the local ethernet adapter (the second adapter). Do not specify DNS and default gateway for this adapter since they are set by your isp.
   4. Specify each client with a unique ip address (192.168.0.2, 192.168.0.3, etc...). Set DNS and the default gateway in each client host to the gateway host ip 192.168.0.1.
   5. If you don't want to specify an ip address for each client, you can use DHCP to simplify the configuration. See next question for the DHCP setup.
      
      If you experience a problem during your NAT mode setup, you can refer to the trouble shooting chapter in the software help manual. We recommend you to read the help file throuthly.


8. I want to use the DHCP daemon to simplify my local network setup, what do I need to do?
   DHCP is a protocol to define how clients can obtain their IP addresses and other network parameters from a central location (a DHCP server). Our software will turn the gateway host to be a DHCP server if you configure the DHCP daemon from the Manager window. For the details, you need to read the help file under Networking->Using a DHCP server chapter. Here I just outline some basic information:
   
   
   1. set your gateway host's local ip to 192.168.0.1 (or other private ip address)
   2. configure DHCP daemon in the Daemon Tab. Click Advanced button to display a window:
      
      
      
      specify a range of IP addresses to be assigned to the clients (must be in the same network with the gateway's ip). click OK and Apply to save your changes. Don't forget to enable DHCP daemon.
   3. in each client pc, do not specify an IP address. Set them to obtain an IP address automatically. This is the default situation after you install a network card.
      
      It is ready to access the Internet.



9. I'm using NAT and my ISP uses a proxy server. Can I still use the Remote Control?
   Assuming that NAT function is working and you have set your browser's proxy settings to your ISP's proxy server. To use the Remote Control in this case, you will need to make several changes under Internet Explorer. First, select Internet Options from the Tools menu. Select the Connections tab, and then click the LAN Settings button. In the window that appears, please check the selection for Bypass proxy server for local addresses. Then, click the Advanced button. Under Exceptions, please enter comsocks.go. Now you should be able to use the Remote Control feature as normal.



10. How can I use Symphoy (Proxim) wireless cards with your software to share my modem by using peer to peer networking?
    You can save a Symphoy Ethernet Bridge (or Conductor Ethernet Sharing Software) or a Symphoy Cordless Modem by using Comtun proxy server software in the gateway host. Our software can enable Multi-user Internet Sharing for Symphoy peer to peer wireless network. Of course, you still need two or more Symphoy PC/ISA/PCI Cards to bring two or more computers together.
    
    The following are the normal installation steps:
    
    1. Install and Configure Symphony Cards in both computers per Symphony Installation Guid (Speicify Security Codes, Creating Profile, etc...)
    2. Install Client for Microsoft Network, File and Printer Sharing for Microsoft Networks in the Network Neighborhood Configuration.
    3. Test Symphony Cards, make sure that you can share files between two computers
    4. Configure network properties in the gateway host (connecting to the Internet directly). Highlighting TCP/IP -> Symphony HRF PC Card, specifying IP 192.168.0.1 with subnet 255.255.255.0. NO DNS and Default Gateway settings.
    5. Configure network properties in the client host. Highlighting TCP/IP -> Symphony HRF PC Card, specifying IP 192.168.0.2 with subnet 255.255.255.0, set DNS and the Default Gateway to 192.168.0.1.
    6. Install Comtun in the gateway host (192.168.0.1) only and specify 192.168.0.1 as its proxy ip.
    
    Steps 1,2,3 are normal Symphony Card installation steps under peer to peer networking to share files. If you do not know how to configure network properties, please see the on-line manual here.



11. How can I use Comtun/Comsocks as a firewall?
    Current Comtun 4.0 or later release has a built-in firewall. You can adjust the security level under the firewall tab. We strongly recommend you to upgrade to the latest version in order to completely secure your gateway host and the local network. The previous Comtun/Comsocks version is a basic network firewall through NAT or proxy function (not configurable), it can protect your LAN if the gateway itself is secure and Comsocks has no inbound port mappings. In order to protect your gateway better under the previous Comsocks (v3.08(a) and below) a special care must be taken to protect the gateway. Please follow some general rules to maximize the gateway's security:
    1. Always DISABLE file and printer sharing. Please see the q4.
    2. Always select strong admin and user passwords for Windows NT/2000. Change them regularly.
    3. Set a "RestrictAnonymous" REG_DWORD value to 1 in "HKLM\CurrentControlSet\Control\lsa" registry in Windows NT to disallow anonymous access.
    4. Do NOT run any unnecessary server software (eg. IIS) other than Comsocks.
    5. Only install and run minimal applications and services in the gateway host. Disable unnecessary services.
    6. In Windows NT, enable TCP/IP security and filtering under Microsoft TCP/IP Properties (Control Panel->Network->Protocol->TCP/IP->Advanced->Enable Security). Only allow those ports and protocols necessary to the function of the gateway. You can block TCP/UDP ports 135-139 for NETBIOS access(file sharing).
    7. In Windows NT, disable Guest account.
    8. In Windows NT, remove Everyone from the Access This Computer From The Network User Right under "Policies->User Rights" in User Manager.
    9. Apply the most recent Service Packs and security fixes.
    10. Enable Auditing in Windows NT.
    11. Upgrade to the Comtun latest version to maximize the protection. Or you can install a third-party firewall software to protect the gateway (e.g. Tiny Personal Firewall, ZoneAlarm Firewall, BLACKICE Defender, Nortan Internet Securty, etc...).
    12. Install third-party anti-virus software.
    13. Using third-party port scan or security detection software to test your security holes (eg. Steve Gibson's web site has a ShieldsUp).
    14. Restrict physical access to the host. Leave the server alone.
    15. Do NOT use the gateway host as your regular workstation.
        
        
12. I try to install Comtun/ComSocks on Windows 2000, but the Linkbyte CKDriver does not appear on my protocols list. What do I do?
    

    Login your Windows as a System Administrator. Other logins won't have the permission to install new drivers.If you are using Comtun 4.00/4.00a, you can run a reinstall wizard under the File menu of the Comtun Manager. For a previous version, please open a DOS command prompt and enter:
    
    INSTALL_PATH\ckinst2k.exe -i "INSTALL_PATH", where "INSTALL_PATH" is the installation directory of Comtun/ComSocks.
    
    

13. We'd like to restrict browser (HTTP?) access, but not email access to some users/PCs? how do we do that? do we use proxy instead of NAT?
    What's the use of the USERS tabbed folder on the Comtun Manager?
    

    If you want to restrict HTTP access but not the email access,
    
    (1) you need to create Users/Groups or Workstations under the Users tab. You will need those information in the HTTP Access Tab under the advanced configuration properties of HTTP cache daemon. Then your clients can enter their username/password to access HTTP connection.
    
    (2) you need to enable HTTP cache module (you need to add valid users in the HTTP cache daemon -> advanced -> access tab). You also want to use the firewall to block NAT for direct HTTP connection. The easiest way is to change the security level to HIGH then enable Allow Outgoing Email firewall rule in the firewall rule customized window for email NAT function. Of course, the NAT function should be enabled under the Adapters tab.
    
    (3) you need to configure the client host's Internet Explorer to use the Proxy Server. Normally, the proxy server ip address is 192.168.0.1 (unless you have set a different proxy ip in the gateway host) and port 80.
    
    (4) You need to configure your email software in the client hosts to use your ISP's email server. You should use the same configuration as you configure it in the gateway host.

14. Can we run Comtun Proxy Server as a web server? How?
    

    If you are using Comtun v4.00.06a (build 6) or a later version with an unlimited license, you can run the web server together. Comtun v4.00.06a has the Apache Web Server v1.3.23 included. You need to create a directory htdocs under the Comtun installation directory and copy all your files (HTML) into this directory. If you want to customize the web server, you need to edit the httpd.sam file. This file will be used to create the HTTPD configuration file httpd.conf dynamically under the conf directory. Please add the following line to the end of the httpd.sam file:
    
    Listen IP:80
    
    where IP is the Internet IP address of your web server. By default, the web server only listen to the local ip address of the Comtun proxy server. Then you need to enable HTTP cache daemon in Comtun proxy server. Apply the changes and restart the proxy engine. If you want to know about the web server configuration file, please refer to the Apache Web Server's documents at www.apache.org.

15. I want to configure all my clients to use the proxy cache module provided by Comtun, How can I use an automatic configuration script to automate my client host's proxy settings?
    

    You must use Comtun v4.00.06a (build 6) or a later version. Please edit a file proxy.pac under the Comtun installation directory and set your proxy ip address correctly. Then copy this file into the directory htdocs(please create the directory as needed). Enable the HTTP cache daemon in Comtun and restart the proxy engine. In each of your client host, please configure Internet Explorer to use this script by edit Internet Options->Connections->LAN Settings, add the following line:
    
    http://192.168.0.1/proxy.pac
    
    into the Address text box besides the check box Use automatic configuration script. Check mark this box.
    
    where 192.168.0.1 is your proxy server's local ip address.

16. I want to run a web and/or ftp server on one of my internal system, how can I let users on the internet to access my server behind Comtun firewall?
    

    First thing, you need to enable Allow Web Server and Allow FTP server in the firewall customized rule window in the Firewall Setup Tab in the manager. Case 1, you can run a web server or a ftp server coexisting with Comtun proxy server. You may need to configure HTTP daemon and define a different proxy port other than 80 (e.g. 8080) if you don't use NAT mode. Case 2, if you run the web server or ftp server on a different host, you need to add a port mapping for each of them. The gateway IP address should be fixed and not be dynamically assigned otherwise it may change at the next time (you need a DNS server to map your ip address. We provide this service at $20/year). You also need to uncheck the option "Use this proxy IP for all daemons and port mappings" in the General Tab.
    
    To configure a port mapping for:
    HTTP Web Server^*:
    
    Port Mapping’s Name: Web Server Port Mapping
    Proxy IP Address: Proxy Port: fixed_Internet_ip : 80
    Destination Name or IP: local web server’s host or IP, e.g. 192.168.0.2
    Destination Port: 80 (your web server’s port)
    Messages come from sender's Port: 0
    Proxy server uses this Port to send messages: 0
    Transport: tcp
    Rule: General
    Bi-directional UDP mapping: [blank]
    
    
    FTP Server^*:
    
    Port Mapping's Name: FTP Server Port Mapping
    Proxy IP Address:Proxy Port: fixed_Internet_ip : 21
    Destination Name or IP: local ftp server's host or IP, e.g. 192.168.0.2
    Destination Port: 21 (your ftp server's port)
    Messages come from sender's Port: 0
    Proxy server uses this Port to send messages: 0
    Transport: tcp
    Rule: FTP
    Bi-directional UDP mapping: [blank]
    
    ^*You need an unlimited client license to implement this feature (because you have many clients).

17. I have a DirectPC satellite connection, but the client throughput is a bit of slow, how can i fix this problem?
    
    Client speed can be the same as the sever with a little tweaking- goto www.copperhead.cc/tips.html for tips. You can download the software DRTCP v2.1 zip file here. Please install DrTCP on every computer. Copy down every thing on the Host PC (Satellite PC)under the USB Satellite Adatper and apply the same settings to all other PCs on their respective Ethernet Adapter (NIC). You may need to reboot each system after the changes. this change is necessary to cope with the high latency of a satellite connection and we want to take advantage of the optimized settings in the host pc.
    
    
    The next step is to improve the IE browser's performance. you need to increase the maximum tcp connections per server to 21 from the windows default value 2 or 4 for each client pc. windows normally downloads a page when it finishes the previous download. by increasing the maximum tcp connections, windows can open simultaneous downloads instantly and overcome the latency delay between connections.
    
    Here are the registry keys you need to add in order to increase your HTTP connections. As these are all DWORD values, when you put a value in them it will default to Hexadecimal representation unless you select Decimal (ie. Hex 15 = Decimal 21). I recommend that you DO NOT set the value greater than HEX 15 or Decimal 21 as you may get FAP'd for doing so and at 21, you are already past the point of diminishing returns. Create these keys in regedit as DWORD values and set the value to HEX 15 or Decimal 21.
    
    Win2k: All DWORD Values
    
    HKEY_USERS/.DEFAULT/Software/Microsoft/Windows/CurrentVersion/Internet Settings
    
    MaxConnectionsPerServer
    MaxConnectionsPer1_0Server
    
    HKEY_CURRENT_USER/Software/Microsoft/Windows/CurrentVersion/Internet Settings
    
    
    MaxConnectionsPerServer
    MaxConnectionsPer1_0Server
    
    WINME / 98 All DWORD Values
    
    HKEY_CURRENT_USER/Software/Microsoft/Windows/CurrentVersion/Internet Settings
    MaxConnectionsPer1_0Server
    MaxConnectionsPerServer
    
    
    What? you want a way to test those tweakings?
    ok. I have found that the web site dslreports.com has an online tweaking testing tool. please click Tweaktester.



18. I forget my login password, what am i going to do?
    
    You need to reset or delete the following key value from the windows registry:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\LinkByte\Comsocks\CurrentVersion\Users\userlist\Administrator\Pwd
    
    You can use the windows registry editor regedit.exe.



19. How do i configure the POP3 or SMTP daemon to filter my emails?
    
    The following statement is for the version v4.6a or a later release.
    
    (1)The POP3 daemon will provide a filtering for any incoming emails from the remote POP3 server. You need to set the remote POP3 mail server in the General tab of the POP3 daemon Settings window. You may want to log any emails by checking the Log regular emails option. Then you will enable any or all of the filtering rules in the Rules and Filters tab. In general, you can enable Block Executable Attachments, String Matching, and DNS-based Blocklist Services. If you have a Spam Assassin server running, you can enable the Spam Assassin rule (Spam Assassin client). If the email message matches the rule or filters, the message will be marked as *SPAM* or *BLOCK* in the subject. However, the POP3 daemon will still deliver the message to your email software. You should configure the email software to delete those messages. This is straight forward if you are using Outlook Express 6. You will create a mail rule under Tools->Message Rules->Mail...->Message Rules window->New... and specify that <Where the Subject line contains specifc words> with *SPAM* or *BLOCK* as the rule condition and <Delete it> or <Mark the message as watched or ignored> and <Stop processing more rules> as the rule actions.
    
    (2)The SMTP daemon will provide a filtering for emails sending to the SMTP server. The SMTP server can be a remote smart host server provided by your ISP or a local mail server^* running inside the network. If it is a remote server, you will configure the SMTP daemon to listen a local ip address (e.g. 192.168.0.1) in the Daemon configuration window. And check mark the Relay for outgoing mails option in the settings window. If it is a local mail server, the listening ip address should be the gateway's internet ip and uncheck the Relay for outgoing mails option. Other settings are similar to the POP3 cofiguration. However, you will not need to enable the DNS-based Blocklist Services rule if the smtp server is remote. If a message is matched or marked, it will be rejected by the daemon. You can change this behaviour by unchecking the Reject marked as spam or blocked emails option in the Rules and Filters tab.
    
    (3)In the email software, e.g. Outlook , Outlook Express, you must set the POP3 server and the SMTP server to the gateway's ip (e.g. 192.168.0.1). This configuration is under Outlook or Outlook Express Tools->Accounts...->Mail tab->Properties->Servers tab.
    
    
    ^*You need an unlimited license to run an email server locally.



20. How do I tune a NT workstation to achieve a server-like performance?
    
    You can run our Comtun proxy software on a workstation. However, NT Workstation and NT Server have vastly different performance characteristics due to the internal tuning that the NT operating system, which is identical on both, performs. Most tuning parameters are inaccessible, but a few are located in the Registry. If you are running Server and you double-click on the Server entry of the Services tab in the Control Panel's Network applet, you will get a dialog that lets you determine what type of application you want the machine to be tuned for. Choices let you select between "Minimize Memory Used", "Balance", "Maximize Usage for File Sharing", and "Maximize Usage for Network Applications". This dialog box is not presented on Workstation installations. The various selections actually change the values of two Registry values:
    
    HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\LargeSystemCache
    
    and
    
    HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\Size
    
    This table presents the settings you should select on a Workstation to achieve the same effect you would get using the dialog box were your system a Server.
    
    

    Tuning Target	LargeSystemCache	Size
    Minimize Memory Used	0	1
    Balance	0	2
    File Sharing	1	3
    Network Applications	0	3

    
    ^*This information is provided by SysInternals



21. How can I configure TCP/IP settings from the Command Prompt?
    
    Under Windows 2000, XP or 2003, you can use a tool "netsh.exe" in a DOS command window to configure all tcp/ip settings including the IP address, subnet mask, default gateway and dns. Here are some examples:
    
    To obtain a network interface name
    netsh int ip show config
    
    To set the IP address, subnet mask, and default gateway to 192.168.0.100, 255.255.255.0, and 192.168.0.1 respectively for the interface "Local Area Connection"
    netsh int ip set address "Local Area Connection" static 192.168.0.100 255.255.255.0 192.168.0.1 0
    
    To set the DNS to 192.168.0.1
    netsh interface ip set dns "Local Area Connection" static 192.168.0.1
    
    To use a DHCP server
    netsh int ip set address "Local Area Connection" dhcp
    netsh int ip set dns "Local Area Connection" dhcp
    
    Basically, you can use the Netsh.exe tool to perform the following tasks:
    
    
    • Configure interfaces
      
    • Configure routing protocols
      
    • Configure filters
      
    • Configure routes
      
    • Configure remote access behavior for Windows-based remote access routers that are running the Routing and Remote Access Server (RRAS) Service
      
    • Display the configuration of a currently running router on any computer
      
    • Use the scripting feature to run a collection of commands in batch mode against a specified router.
      
    
    
    Links:
    How to Use the Netsh.exe Tool and Command-Line Switches - 242468
    How to Use the NETSH Command to Change from Static IP Address to DHCP in Windows 2000 - 257748