1. Assign CHAP secrets to all trusted callers

Create, or have the callers create, their CHAP secrets.

2. Create the chap-secrets database

Add the security credentials for all trusted callers to the /etc/ppp/chap-secrets file.

3. Modify the PPP configuration files

Add options specific to CHAP to the /etc/ppp/options and /etc/ppp/peers/peer-name files.

1. Create the CHAP database for the trusted caller's machine

Create the security credentials for the trusted caller and, if necessary, security credentials for other users who call the dial-out machine, in /etc/ppp/chap-secrets.

2. Modify the PPP configuration files

Add options specific to CHAP to the /etc/ppp/options file.