Hi Jow,
Thank you so much for your kindly help.
1. without fw3 restart,
/tmp# opkg install kmod-ipt-raw
Installing kmod-ipt-raw (4.14.63-1) to root...
Downloading https://downloads.openwrt.org/releases/18.06.1/targets/brcm47xx/legacy/packages/kmod-ipt-raw_4.14.63-1_mipsel_mips32.ipk
Configuring kmod-ipt-raw.
root@tplink:/tmp#
====then restart pptp client built-in the openwrt 18.06.1=======
/tmp# logread |grep ppp
Fri Sep 21 22:53:36 2018 daemon.info pppd[7330]: Plugin pptp.so loaded.
Fri Sep 21 22:53:36 2018 daemon.info pppd[7330]: PPTP plugin version 1.00
Fri Sep 21 22:53:36 2018 daemon.notice pppd[7330]: pppd 2.4.7 started by root, uid 0
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7331]: pptp: call manager for xx.xx.xx.xx
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7331]: window size: 50
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7331]: call id: 3
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7331]: control connection
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7331]: unix_sock
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7332]: Sent control packet type is 1 'Start-Control-Connection-Request'
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7332]: Received Start Control Connection Reply
Fri Sep 21 22:53:36 2018 daemon.debug pppd[7332]: Client connection established.
Fri Sep 21 22:53:37 2018 daemon.debug pppd[7332]: Sent control packet type is 7 'Outgoing-Call-Request'
Fri Sep 21 22:53:37 2018 daemon.debug pppd[7332]: Received Outgoing Call Reply.
Fri Sep 21 22:53:37 2018 daemon.debug pppd[7330]: using channel 3
Fri Sep 21 22:53:37 2018 daemon.debug pppd[7332]: Outgoing call established (call ID 3, peer's call ID 52439).
Fri Sep 21 22:53:37 2018 daemon.info pppd[7330]: Using interface pptp1
Fri Sep 21 22:53:37 2018 kern.info kernel: [351466.656057] pptp1: renamed from ppp0
Fri Sep 21 22:53:37 2018 daemon.notice pppd[7330]: Connect: pptp1 <--> pptp (xx.xx.xx.xx)
Fri Sep 21 22:54:36 2018 daemon.debug pppd[7332]: Echo Request received.
Fri Sep 21 22:54:36 2018 daemon.debug pppd[7332]: Sent control packet type is 6 'Echo-Reply'
Fri Sep 21 22:55:36 2018 daemon.debug pppd[7332]: Echo Request received.
Fri Sep 21 22:55:36 2018 daemon.debug pppd[7332]: Sent control packet type is 6 'Echo-Reply'
Fri Sep 21 22:55:36 2018 daemon.debug pppd[7332]: Echo Reply received.
Fri Sep 21 22:55:38 2018 daemon.debug pppd[7332]: Received Call Clear Request.
Fri Sep 21 22:56:09 2018 daemon.warn pppd[7332]: read returned zero, peer has closed
Fri Sep 21 22:56:09 2018 daemon.debug pppd[7332]: Closing connection (shutdown)
Fri Sep 21 22:56:09 2018 daemon.debug pppd[7332]: Sent control packet type is 12 'Call-Clear-Request'
Fri Sep 21 22:56:09 2018 daemon.warn pppd[7332]: read returned zero, peer has closed
Fri Sep 21 22:56:09 2018 daemon.debug pppd[7332]: Closing connection (call state)
/tmp#
2. After fw3 restart,
I get the 2 records about pptp in iptables -t raw -nvL, but the pptp client is always " Interface is reconnecting...", and no output from the "logread |grep ppp".
Chain zone_lan_helper (1 references)
pkts bytes target prot opt in out source destination
0 0 CT tcp -- * * 0.0.0.0/0 0.0.0.0/0 /* !fw3: PPTP VPN connection tracking */ tcp dpt:1723 CT helper pptp
Chain zone_root_helper (0 references)
pkts bytes target prot opt in out source destination
0 0 CT tcp -- * * 0.0.0.0/0 0.0.0.0/0 /* !fw3: PPTP VPN connection tracking */ tcp dpt:1723 CT helper pptp
3. after reboot the OpenWRT, then restart the pptp client, the error is the same.
/# logread |grep ppp
Fri Sep 21 23:27:29 2018 daemon.info pppd[1296]: Exit.
Fri Sep 21 23:27:31 2018 daemon.info pppd[1816]: Plugin pptp.so loaded.
Fri Sep 21 23:27:31 2018 daemon.info pppd[1816]: PPTP plugin version 1.00
Fri Sep 21 23:27:31 2018 daemon.notice pppd[1816]: pppd 2.4.7 started by root, uid 0
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1819]: pptp: call manager for xx.xx.xx.xx
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1819]: window size: 50
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1819]: call id: 2
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1819]: control connection
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1819]: unix_sock
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1820]: Sent control packet type is 1 'Start-Control-Connection-Request'
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1820]: Received Start Control Connection Reply
Fri Sep 21 23:27:31 2018 daemon.debug pppd[1820]: Client connection established.
Fri Sep 21 23:27:32 2018 daemon.debug pppd[1820]: Sent control packet type is 7 'Outgoing-Call-Request'
Fri Sep 21 23:27:32 2018 daemon.debug pppd[1820]: Received Outgoing Call Reply.
Fri Sep 21 23:27:32 2018 daemon.debug pppd[1820]: Outgoing call established (call ID 2, peer's call ID 30370).
Fri Sep 21 23:27:32 2018 daemon.debug pppd[1816]: using channel 2
Fri Sep 21 23:27:32 2018 kern.info kernel: [ 358.189112] pptp1: renamed from ppp0
Fri Sep 21 23:27:32 2018 daemon.info pppd[1816]: Using interface pptp1
Fri Sep 21 23:27:32 2018 daemon.notice pppd[1816]: Connect: pptp1 <--> pptp (xx.xx.xx.xx)
Fri Sep 21 23:28:31 2018 daemon.debug pppd[1820]: Echo Request received.
Fri Sep 21 23:28:31 2018 daemon.debug pppd[1820]: Sent control packet type is 6 'Echo-Reply'
Fri Sep 21 23:29:31 2018 daemon.debug pppd[1820]: Echo Request received.
Fri Sep 21 23:29:31 2018 daemon.debug pppd[1820]: Sent control packet type is 6 'Echo-Reply'
Fri Sep 21 23:29:31 2018 daemon.debug pppd[1820]: Echo Reply received.
Fri Sep 21 23:29:32 2018 daemon.debug pppd[1820]: Received Call Clear Request.
Fri Sep 21 23:30:03 2018 daemon.warn pppd[1820]: read returned zero, peer has closed
Fri Sep 21 23:30:03 2018 daemon.debug pppd[1820]: Closing connection (shutdown)
Fri Sep 21 23:30:03 2018 daemon.debug pppd[1820]: Sent control packet type is 12 'Call-Clear-Request'
Fri Sep 21 23:30:03 2018 daemon.warn pppd[1820]: read returned zero, peer has closed
Fri Sep 21 23:30:03 2018 daemon.debug pppd[1820]: Closing connection (call state)