xl2tpd - Layer 2 Tunneling Protocol Daemon.

       Forked from l2tpd by Xelerance: https://github.com/xelerance/xl2tpd

       Michael Richardson <mcr@xelerance.com>
       Paul Wouters <paul@xelerance.com>
       Samir Hussain <shussain@xelerance.com>

       Previous development was hosted at sourceforge (http://www.sourceforge.net/projects/l2tpd) by:

       Scott Balmos <sbalmos@iglou.com>
       David Stipp <dstipp@one.net>
       Jeff McAdams <jeffm@iglou.com>

       Based off of l2tpd version 0.61.  Many thanks to Jacco de Leeuw <jacco2@dds.nl> for maintaining l2tpd.
       Copyright (C)1998 Adtran, Inc.
       Mark Spencer <markster@marko.net>

                                                    Jan 2022                                           xl2tpd(8)

       Please use the github project page https://github.com/xelerance/xl2tpd to send bugreports, issues and any
       other feedback.

       Alexander Dorokhov <alex.dorokhov@gmail.com>
       Alexander Naumov <alexander_naumov@opensuse.org>

       This  program  is  free  software;  you  can  redistribute it and/or modify it under the terms of the GNU
       General Public License as published by the Free Software Foundation; either version 2 of the License,  or
       (at your option) any later version.

       This  program  is  distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General  Public
       License for more details.

       You  should  have received a copy of the GNU General Public License along with this program (see the file
       LICENSE); if not, see https://www.gnu.org/licenses/,  or  contact  Free  Software  Foundation,  Inc.,  51
       Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

       xl2tpd is an implementation of the Layer 2 Tunneling Protocol (RFC 2661).  L2TP allows to tunnel PPP over
       UDP.  Some ISPs use L2TP to tunnel user sessions from dial-in servers (modem banks, ADSL DSLAMs) to back-
       end PPP servers.  Another important application  is  Virtual  Private  Networks  (VPN)  where  the  IPsec
       protocol is used to secure the L2TP connection (L2TP/IPsec, RFC 3193).

       xl2tpd  works  by  opening a pseudo-tty for communicating with pppd.  It runs completely in userspace but
       supports kernel mode L2TP.

       xl2tpd supports IPsec SA Reference tracking to enable  overlapping  internak  NAT'ed  IP's  by  different
       clients  (eg  all  clients  connecting  from their linksys internal IP 192.168.1.101) as well as multiple
       clients behind the same NAT router.

       This implementation is based on L2TPd 0.61 from http://www.marko.net/l2tp and patches collected by  Jacco
       de Leeuw at http://www.jacco2.dds.nl/networking/openswan-l2tp.html.

       /etc/xl2tpd/xl2tpd.conf
              Configuration file of xl2tpd, used by default.

       /etc/xl2tpd/l2tp-secrets
              Secrets file, used by default.

       /var/run/xl2tpd/l2tp-control
              Control file, used by default.

       xl2tpd - Layer 2 Tunneling Protocol Daemon.

-D     This option prevents xl2tpd from detaching from the terminal and daemonizing.

       -l     This option tells xl2tpd to use syslog for logging even when -D was specified.

       -c<config_file>
              Set an alternate config file.  Fallback configuration file is /etc/l2tpd/l2tpd.conf.

       -s<secret_file>
              Tells xl2tpd to use an alternate "secrets" file.

       -p<pid_file>
              Set an alternate pid file.  Default is /var/run/xl2tpd/xl2tpd.pid.

       -C<control_file>
              Set an alternate control file.

xl2tpd.conf(5), xl2tpd-control(8), pppd(8)