apenas deixe o xl2tpd rodar no userspace, ele será mais lento, mas funciona para mim
FYI - não me sinto lento.
source: my daemon.log
Oct 4 18:29:39 tk xl2tpd[22238]: Enabling IPsec SAref processing for L2TP transport mode SAs
Oct 4 18:29:39 tk xl2tpd[22238]: IPsec SAref does not work with L2TP kernel mode yet, enabling forceuserspace=yes
Oct 4 18:29:39 tk xl2tpd[22238]: setsockopt recvref[30]: Protocol not available
Oct 4 18:29:39 tk xl2tpd[22238]: This binary does not support kernel L2TP.
Oct 4 18:29:39 tk xl2tpd[22239]: xl2tpd version xl2tpd-1.3.1 started on tk PID:22239
Oct 4 18:29:39 tk xl2tpd[22239]: Written by Mark Spencer, Copyright (C) 1998, Adtran, Inc.
Oct 4 18:29:39 tk xl2tpd[22239]: Forked by Scott Balmos and David Stipp, (C) 2001
Oct 4 18:29:39 tk xl2tpd[22239]: Inherited by Jeff McAdams, (C) 2002
Oct 4 18:29:39 tk xl2tpd[22239]: Forked again by Xelerance (www.xelerance.com) (C) 2006
Oct 4 18:29:39 tk xl2tpd[22239]: Listening on IP address 0.0.0.0, port 1701