Setup on CentOS 4
# cat /etc/ppp/ip-up.local
lynx -mime_header -auth=username:password “http://www.3322.org/dyndns/update?system=dyndns&hostname=name.3322.org”
# chmod +x /etc/ppp/ip-up.local

Setup on Debian Sarge
#cat /etc/ppp/ip-up.d/02-dyndns
lynx -mime_header -auth=username:password “http://www.3322.org/dyndns/update?system=dyndns&hostname=name.3322.org”
#chmod +x /etc/ppp/ip-up.d/02-dyndns