3. Connecting your RedHat Linux System to the World using PPP

Contents of this section

You need the following information about the ``far end'' of your connection (ie from your Internet Service Provider - ISP) :

The telephone number to dial to reach their modems.
Your user name on your ISP's system.
Your password on your ISP's system.
The IP number for your system (most likely this is NOT needed as your ISP's system will dynamically give you an IP number each time you dial in).
The IP number(s) of your ISP's Domain Name Servers.
How your ISP starts PPP on his system when you dial in - specifically, does PPP start automatically when you connect or are you required to type in a command to start it.

You also need to know how your ISP's system prompts you for your username and password. The simplest way to find this out is to dial in using Minicom, capture the entire log in process to a file and print this out.

(This is also useful as it checks the modem configuration and serial port set up - make sure that your modem's ``stored'' configuration works fine for connecting to your ISP).

Make sure you have installed the PPP daemon (all RedHat precompiled kernels support PPP). To check this, login as root and type


        rpm -qa | grep ppp

Your RedHat system should respond with something like


        ppp-2.1.2d-2  (for a Linux 1.2.13 kernel)
        ppp-2.2....   (for a Linux 1.3.x kernel)

If you do NOT have the PPP daemon installed, do this now.

Make sure you are logged in as root.

The file /usr/sbin/ppp-on is a script for you to edit. When you have finished editing it, running this script will connecct your machine to your ISP.

Copy this file (so you still have the original version if you mess up your editing).
```
        cp /usr/sbin/ppp-on /usr/sbin/ppp-<your ISP name>
```
where <your ISP name> is something you remember and easy to type!
Using your favourite editor, edit /usr/sbin/ppp-<your ISP name>
- Find the line that says
```
                LOCKDIR=/var/spool/lock
```
  and change it to
```
                LOCKDIR=/var/lock
```
- Find the line that says
```
                DEVICE=com1
```
  and change it to read cua0 (DOS com1:), cua1 (DOS com2:) etc - the serial port on which you have your modem. If your modem is on DOS com2:, the line should read.
```
                DEVICE=cua1
```
- Find the lines that read
```
                PHONE=4511234
                USER=Pkarl
                PASSWORD=password
                OUR_IP_ADDR=137.175.6.3
```
  and change them so that they are the phone number, user name, password and IP number you must use to dial and log into your ISP. Remember - most ISP's are using Unix based machines (such as Linux), so you MUST get the upper/lower case RIGHT! If your ISP is giving you a "temporary" (dynamic) IP number each time you dial in, use the "dummy" IP number of 0.0.0.0
- Find the line
```
                stty 19200 -tostop
```
  and change it to
```
                stty 38400 -tostop
```
- Now we edit the "chat" script. Find the line that reads
```
                if chat -l LCK..$DEVICE ABORT "NO CARRIER" ABORT BUSY "" \
                  ATZ OK ATs50=255s111=0DT$PHONE CONNECT "" \
                  ogin: $USER ssword: \\q$PASSWORD
```
  (NB This is ALL ONE LINE - but broken here with '\' for readability. It MUST be all one line in your script - and the spaces before the '\' are important!) Change this line to read
```
                if chat -l LCK..$DEVICE ABORT "NO CARRIER" ABORT BUSY "" \
                  ATZ OK ATDT$PHONE CONNECT "" \
                  ogin: $USER ssword: \\q$PASSWORD
```
  Now - if your ISP's system uses prompts other than ``...ogin:'' to ask for your user name and ``...assword:'' to ask for your password, you must change these two elements to reflect the prompts your system sees.
- Find the line
```
                pppd asyncmap 0 -detach modem crtscts mru 1500 $OUR_IP_ADDR: \
                  /dev/$DEVICE
```
  (Again, this must all be on one line - but for readability it is broken at '\'). Change this by adding the defaultroute option.
```
                pppd asyncmap 0 -detach modem crtscts defaultroute mru 1500 \
                  $OUR_IP_ADDR: /dev/$DEVICE
```
If your ISP requires you to type in something else to start PPP on his system when you dial in, or if he is using PAP/CHAP, consult the PPP Client HOWTO and/or the man pages on chat and pppd.
Save this file.
Again as root, edit the file /etc/resolv.conf and add the IP number(s) of your IPS's name servers. Your /etc/resolv.conf should look like
domain <your ISP's domain name> nameserver XX.XX.XX.XX
Where <your ISP's domain name> is something like
redhat.com
and the XX.XX.XX.XX is the IP number for the domain name server you obtained from your ISP. (If your ISP gave you more than one IP number, that's fine, out them all in, each one on a separate line, preceded by the key word nameserver).
Save this file.
Now dial in and enjoy!

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