Hi Alexander, Thank for replying me! I tried follow your ideas. My if-down script was not working. However i find out this issue regrading xl2tpd. In/Makefile/ of xl2tpd source code v 1.3.6 : "/-DTRUST_PPPD_TO_DIE // // ...// // # The cost of not trusting pppd to die (and shoot it down hard), is that your// // # pppd's //*ip-down scripts*//will not have a chance to run/." So i just enable /-DTRUST_PPPD_TO_DIE /and rebuild xl2tpd. The problem solved. My if-down script 's working well now! Greetings ! Nam.