Connecting TINI to an IP Network

11 May

Connecting TINI to an IP Network: In this chapter, we will examine various aspects of TCP/IP networking with TINI, with a special emphasis on using a modem to connect TINI to the Internet via PPP. We’ll begin with a very basic discussion on how to construct an IP network consisting of a TINI and a PC, then work our way up to using TINI with a modem. We will do examples in which a TINI dials out to an ISP, and behaves as a PPP client on the Internet, as well as examples in which we use a PC to dial into a TINI, with the TINI acting as a PPP server. Throughout this chapter, we will be assuming that the primary Java application running on TINI is slush. If you aren’t familiar with basic networking concepts, now would be a good time to review Chapter 2. Reviewing the discussion of RS232 in Chapter 9 may also be helpful.

The ipconfig Command
The first step in putting a TINI stick on an IP network is to confaddress. The IP address, and a variety of other network parameters, are set up using the slush command, ipconfig. Let’parameters.

The command is issued:
ipconfig <options> where the options are as follows.
-a XX.XX.XX.XX
Sets the IP address of your TINI stick. You must use the –a option with the –m
option, which sets the subnet mask. For example,
ipconfig –a 192.168.0.5 –m 255.255.255.0
-n domain_name
Allows you to set the domain name of the network on which this stick will reside,
for example,

ipconfig –n stick.net.
-m XX.XX.XX.XX
Sets the subnet mask. This must be used with the –a option, for example,
ipconfig –a 192.168.0.5 –m 255.255.255.0
-g XX.XX.XX.XX

Sets the IP address of the gateway on your TINI network. A gateway, in this context, is a machine with two network interfaces capable of performing IP forwarding or routing between the two interfaces. For example, one network interface on the gateway could be connected to a local network (containing several TINI sticks) and the other could be attached to the Internet. The gateway, in this case, would forward data from your local TINI network to the Internet. Data destined for an address not on the local network is sent to the gateway, which is sent out to the Internet. The gateway IP address must be on the same subnet as the TINI’s IP address. For instance, if we stick with the example above, and our TINI has an IP address of 192.168.0.5 with a subnet mask of 255.255.255.0, our gateway must be on the 192.168.0.X subnet. Thus, we could make our gateway, 192.168.0.3

ipconfig –g 192.168.0.3

This tells our stick that, on its local network, the machine at 192.168.0.3 is the device acting as gateway.
-p XX.XX.XX.XX

Sets the IP address of the primary dynamic name service (DNS) that your  TINI will use. The DNS translates textual domain names into IP addresses. For instance, if you attempt to run the command ftp dalsemi.com  on TINI, there must be a DNS query performed that will translate dalsemi.com into an IP address.

ipconfig –p 192.168.20.80

This tells our stick that the machine at 192.168.20.80 is its primary DNS server. Note that it could only get to this machine if there were a gateway on the local network that provided access to the network on which 192.168.20.80 resides.

-s XX.XX.XX.XX

Sets the IP address of the secondary dynamic name system (DNS) that your TINI will use. If  the primary DNS does not respond to a query, the secondary DNS will be queried.

ipconfig –p 192.168.20.88
-t dns_timeout

Sets the timeout, in milliseconds, for DNS queries. A value of 5000 translates into 5 seconds, and establishes that TINI will wait 5 seconds after making a DNS query before timing out, and giving up in the query. A value of 0 establishes a backoff and retry protocol, that makes a second attempt after 2 seconds, then waits 4 seconds and tries again, then waits 8 seconds and tries again, then tries after 16 more seconds, before it gives up. For example,

ipconfig –t 5000

-d
Tells TINI to use dynamic host configuration protocol (DHCP) to obtain a temporary, server assigned, IP address.
ipconfig –d
-r
Tells TINI to release the temporary, server assigned, IP address obtained via dynamic host configuration protocol, and the –d option.
ipconfig –r
-x
Shows all of the current IP settings.
ipconfig –x

-h XX.XX.XX.XX
Sets the IP address of the mail host for use with the sendmail slush command.
This must be an address on the local network, or an address that can be reached
via a gateway on the network. For example,
ipconfig –h 192.168.0.12

-C
Commits the current network settings to flash memory. The network settings are stored in the heap, which is in RAM. The RAM is nonvolatile, so your settings are still stored on power down. However, there are times when you may want to clear the heap, which can clear your network settings. Committing them to flash memory allows you clear the heap and have TINI restore your settings on reboot. If, upon reboot, you have settings in flash and on the heap that are different, the settings in flash are written over those in the heap. You can only use the –C option once, and then you have to erase bank 7 of the flash before you can use it again. That is, once you’ve written settings to the flash, they have to be erased before you can write different settings. You do this by reloading tini.tbin and slush.tbin.
ipconfig –C

-D
De-commits the settings previously committed to flash by the –C option. If you commit your settings to flash, they will be restored at boot time, overwriting whatever settings you may have previously had on the heap. If you no longer want those settings restored at boot time, you use the –D option. After using –D, your settings will stored on the heap, and the values stored in flash will be ignored. Any previously committed data in flash remains there, so you still have to erase the settings in flash if you want to use the –C option again.
ipconfig -D

-f
Don’t prompt for confirmation. Many of the ipconfig options will cause the FTP and Telnet servers to be shut down and restarted. In these cases, there will be a prompt asking you if this is OK. The –f option suppresses this prompt. You must have admin privileges to use the ipconfig command, and as noted above, it will often shut down the FTP and Telnet servers and restart them.

514-Other relevant network commands

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