TINI as a PPP server using the slush command ppp

11 May

TINI as a PPP server using the slush command ppp
We’re now going to assume that you’ve succeeded in making the changes to slush described in the previous section, and that you’ve succeeded at getting the PPPServer program to work on a TINI. So we know we’ve got a cable that works with your modem, and dialing strings that work, etc. Connect a modem (such as the cell phone) to TINI serial0, Telnet into the TINI via Ethernet as root, and do the following commands. Then, from a PC connected to a second modem, call the modem connected to the TINI. Enter a username and password valid for the TINI you are using.

TINI /> ppp -s -x 0 -a -r

PPP connection established

TINI /> ipconfig -x Interface 0 is active. Name       : eth0

Type          : Ethernet

IP Address   :

Subnet Mask   :

Gateway       :

Interface 1 is active. Name      : lo

Type          : Local Loopback

IP Address   :

Subnet Mask  :

Gateway       :

Interface 2 is active.

Name          : ppp0 (default)

Type          : Point-to-Point Protocol

IP Address    :

Subnet Mask   :

Gateway       :

Interface 3 is not active.

We now have a PPP connection between the TINI and the PC. You can Telnet and FTP over either the Ethernet interface and/or PPP interface. Applications running under Slush can use either also. You don’t have to use the IP addresses shown, just make sure the Ethernet addresses and the PPP addresses are on different networks.


This chapter has examined TINI IP networking, with an emphasis on PPP. We looked at the ipconfig command in detail, and examined how TINI does PPP. Ways of making TINI behave as a PPP client to the Internet or a PPP server to a PC were presented. Examples included standalone applications, as well as implementing the optional ppp command in slush. The ppp command is a convenient, more sophisticated way of achieving PPP connectivity than some of the simpler examples shown. But the process of getting the cable, modem, and PPP software to work together can be difficult, and it pays to take an incremental approach:

1. Learn how to use AT commands with your modem by connecting it to a PC (via a straight-through cable) and talking to it with a terminal emulator.

2. Learn how to get a TINI to properly talk to a modem by using the proven AT commands and a specially made crossover cable. Be mindful that DTR resets the TINI, but may be needed by the modem (as well as RTS).

3. Try dialing out to an ISP, with TINI acting as a PPP client. Remember, the ISP must support PAP (Password Authentication Protocol).

4. Try dialing into TINI from a PC, with TINI acting as a PPP server. This requires two modems and two phone lines. We used a cell phone, with a

special accessory cable that allows it to be used as an RS232 modem. Remem- ber, cell phones and modem may have varied requirements with respect to answering calls.

5. Implement the optional command ppp, by making the modifications described in this chapter, and then following the instructions in Chapter 7 on modifying Slush.

Common problems include the cable (not crossover, not providing DTR and RTS to the modem), failure to shut down the serial server before starting PPP, failure to get rid of old processes/connections before starting up new ones, mixing up java files

during compilation (keep everybody separate), and having an incorrect modem setup. If you run across something that defies explanation, specifically, the case when you receive the UP event but the ppp0 interface never shows up after an ipconfig: clear

the heap, goto JavaKit and fill the flash full of 0’s, and reload the firmware. Last but not least, always be watching the TINI message archives. If you’re having trouble, someone else has probably had the same problem and fixed it.


1. Modem AT commands fall under TIA/EIA/IS707-A.3. Wireless enhance- ments to the command set are covered by ITU-T

recommendation V.250. For more AT command information, visit www.modem.com. For information about cell phones as modems, visit http:// www.shorecom.com/wirelessly.html

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