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Netgear VMDG280 command-line control scripts
Installation: Make sure
lynx is on the system. Unpack netgear.tgz into
/usr/local/bin or wherever, and save the router's admin password into
/etc/netgear-password (readable by any users that need to run the
netgear commands). The scripts assume a LAN IP of 192.168.0.1.
- netgear-add-port (PortNum) (IpNum)
- Add a simple port-forwarding rule to forward incoming port PortNum (1 through 65535) to IpNum (1 through 254), replacing an existing rule if necessary (see netgear-delete-port)
- netgear-block (IpNum)
- Blocks the specified IP number (2 through 254) from making any new connections to the outside Internet. Existing connections are unaffected, and connections on the internal network are still allowed. Also, the computer could change its IP address to an unblocked one (only 30 of them can be blocked), and if the computer has the router password then it can unblock itself as well. It might be better to block by MAC address, which can be scheduled to a time period by the router itself (see "MAC Filtering" in the browser, and use netgear-date to check the router's idea of the current time) and which also stops existing outgoing connections (internal connections still allowed), although some hardware allows MAC changing
- Shows the current date and time from the router. Not always accurate, and there's no obvious way to set it, although it sometimes sets itself after being power-cycled.
- netgear-delete-port (PortNum)
- Delete a port-forwarding rule whose first (or only) port is PortNum. The deletion takes effect only for new connections; existing connections to the port (e.g. open SSH sessions) are not affected.
- So for example if you run a Web server which you only occasionally SSH into, you can reduce the level of SSH probing by keeping the port closed until you need it, open it via a CGI script and close it again from your login script. If you do this via router configuration then the scripts don't need any special privileges on the server itself (apart from being able to read the router's password).
- netgear-dmz [(IpNum)]
- Sets the specified IP number (2 through 254) to receive all incoming traffic that is not handled by port forwarding; 0 turns this off (off is recommended if you might have insecure open ports!) When run without a number, reports the current setting.
- netgear-filter-add (domain)
- Adds a domain to the forbidden websites list, if it's not already listed. The router blocks outgoing HTTP connections (usually sending a "Web Site Blocked by Filter" response, but sometimes just dropping the connection) if any of these domains are mentioned in the request's "Host" header. Subdomains of the specified domains are also covered. HTTPS traffic, and non-Web traffic, is not affected (and neither is connecting to a non-VirtualHost website by IP), but it might help with some situations. Up to 16 domains can be listed.
- Lists forbidden website domains, in the order in which they were added.
- Shows the IP address of the ISP's upstream gateway. If this IP responds to ping, it could be used to test your immediate link. This command has been known to fault occasionally.
- Shows the router's current external IP address. Has been known to fault occasionally.
- netgear-password [(NewPass)]
- Changes the password, also updating /etc/netgear-password (must have write access). If new password is not specified, one is generated at random.
- Tells the router not to respond to ``ping'' requests from outside
- Tells the router to respond to ``ping'' requests from outside. This might help with diagnostics if running a server, and might also lead to a small increase in probing.
- Shows the current status (on or off) of whether the router responds to ``ping'' requests from outside
- Shows the port forwarding table in a simple textual format
- netgear-unblock (IpNum)
- The reverse of netgear-block. Assumes the rule's name has not been changed.
- Shows or sets the WiFi channel (1 to 13 or auto). Setting the channel may break existing connections. "Auto" seems to choose a channel which currently has least interference (it chooses out of the three standard non-overlapping channels 1, 6 or 11, and re-running netgear-wifi-channel auto will re-evaluate its choice), but it doesn't seem to do much accounting for varying interference over time, which is sometimes the cause of intermittent dropouts in a crowded neighbourhood. If a WiFi scanner shows SNR periodically dropping below 25, and you can't find a channel that's 22MHz (5 channel-widths) away from anything stronger than 50dB below your signal level, then you might need to use wired connections, or turn off the Netgear's WiFi and get a better router. (You could improve positioning, but some environments seem to make this router drop connections even if they are 50--60dB stronger than the background; perhaps its firmware is overly sensitive.)
- Lists the IP and MAC addresses of devices that are currently connected to WiFi
- netgear-wifi-macadd (MacAddr)
- Adds the specified MAC address to the WiFi MAC access list. Up to 32 can be added. The list takes effect when "allow any" is turned off in the browser. Note that some devices are capable of changing their MAC addresses, and of observing which MAC addresses have connected, so MAC-based restrictions are effective only against casual users.
- netgear-wifi-macdel (RegExp)
- Deletes from the WiFi MAC address list anything matching the regular expression RegExp, which can be a single MAC address or a regular expression matching multiple addresses (a single dot will match all addresses).
- Outputs the current WiFi MAC access list in a simple textual format.
- Switches off wireless Internet, leaving only wired connections active. Switching the radio off at times when it won't be used might improve security (see below) and/or save a small amount of power.
- Switches wireless Internet back on. Note that the router gives wireless clients access to all the computers on your network, including any ``internal'' services, and WiFi security has been broken before, so you might wish to restrict which services run on your network when WiFi is enabled. You can set up a ``guest network'', but (a) there is no way to run the guest network without also running a private one and (b) users of the guest network can't connect to your own servers even on your public IP address, which must be a bug
- Shows the current status of WiFi (off or on)
All material © Silas S. Brown unless otherwise stated.
Linux is the registered trademark of Linus Torvalds in the U.S. and other countries.
Netgear is a registered trademark of Netgear Inc and/or its subsidiaries in the United States and/or other countries.
Wi-Fi is a trademark of the Wi-Fi Alliance.
Any other trademarks I mentioned without realising are trademarks of their respective holders.