1.login as root
2.type: rm /usr/bin/kppp
3.type: chmod u+s /usr/sbin/kppp
4.type: ln -s /usr/sbin/kppp /usr/bin/kppp
That's what I did to get it working for all users on RH 7.3.I think if you configure your modem and network stuff during install and it asks for ISP info,RH is setting up kinternet for you and it should be accessible to all users.So you can try the above or try kinternet.