Nf_conntrack_helper is missing from kernel 6.0.5

I need to connect to a pptp VPN, but the connection fails.

Before upgrading kernel to version 6.0.5, I solved the issue following these steps.

But now, after running sudo sysctl net.netfilter.nf_conntrack_helper=1 I get:

sysctl: cannot stat /proc/sys/net/netfilter/nf_conntrack_helper: No such file or directory

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Ok. Go to the software store, find and install “firewall” - application with brick wall and computer behind. Open that application, and chose configuration from “runtime” to “permanent”
image

In the list bellow find and check “gre” parameter

Reboot and try to turn on vpn again.

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I have limit on attachements, so there is screnshot with “gre” parameter, you should turn on it

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Ok, that worked. Thank you very much!!!

Hello, similar problem on

Linux fedora 6.0.11-200.fc36.x86_64

the above solutions do not help

Have you tried the solution from here?

Hello Egor, Yes I tried to do it. Enabled the gre option in the firewall.

sudo sysctl net.netfilter.nf_conntrack_helper=1
sysctl: cannot stat /proc/sys/net/netfilter/nf_conntrack_helper: No such file or directory
journalctl -xef -u NetworkManager
Dec 09 12:32:48 fedora NetworkManager[1234]: <info>  [1670578368.4478] vpn[0x5639d9cb4710,70514b23-8b86-4599-86c4-536cdda1b37f,"pptp-vpn"]: starting pptp
Dec 09 12:32:48 fedora NetworkManager[1234]: <info>  [1670578368.4482] audit: op="connection-activate" uuid="70514b23-8b86-4599-86c4-536cdda1b37f" name="pptp-vpn" pid=9101 uid=1000 result="success"
Dec 09 12:32:48 fedora pppd[153518]: Plugin /usr/lib64/pppd/2.4.9/nm-pptp-pppd-plugin.so loaded.
Dec 09 12:32:48 fedora NetworkManager[153518]: Plugin /usr/lib64/pppd/2.4.9/nm-pptp-pppd-plugin.so loaded.
Dec 09 12:32:48 fedora pppd[153518]: pppd 2.4.9 started by root, uid 0
Dec 09 12:32:48 fedora pppd[153518]: Using interface ppp0
Dec 09 12:32:48 fedora NetworkManager[153518]: Using interface ppp0
Dec 09 12:32:48 fedora NetworkManager[153518]: Connect: ppp0 <--> /dev/pts/2
Dec 09 12:32:48 fedora pppd[153518]: Connect: ppp0 <--> /dev/pts/2
Dec 09 12:32:48 fedora NetworkManager[1234]: <info>  [1670578368.7245] manager: (ppp0): new Ppp device (/org/freedesktop/NetworkManager/Devices/20)
Dec 09 12:32:48 fedora pptp[153521]: nm-pptp-service-153511 log[main:pptp.c:353]: The synchronous pptp option is NOT activated
Dec 09 12:32:48 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_rep:pptp_ctrl.c:258]: Sent control packet type is 1 'Start-Control-Connection-Request'
Dec 09 12:32:48 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:781]: Received Start Control Connection Reply
Dec 09 12:32:48 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:815]: Client connection established.
Dec 09 12:32:49 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_rep:pptp_ctrl.c:258]: Sent control packet type is 7 'Outgoing-Call-Request'
Dec 09 12:32:49 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:900]: Received Outgoing Call Reply.
Dec 09 12:32:49 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:938]: Outgoing call established (call ID 5467, peer's call ID 19717).
Dec 09 12:33:09 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:976]: Call disconnect notification received (call id 19717)
Dec 09 12:33:09 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_error:pptp_ctrl.c:205]: Result code is 2 'General Error'. Error code is 0, Cause code is 224
Dec 09 12:33:10 fedora NetworkManager[153518]: Modem hangup
Dec 09 12:33:10 fedora NetworkManager[153518]: Connection terminated.
Dec 09 12:33:09 fedora pptp[153531]: nm-pptp-service-153511 log[call_callback:pptp_callmgr.c:84]: Closing connection (call state)
Dec 09 12:33:09 fedora pppd[153518]: Modem hangup
Dec 09 12:33:10 fedora pppd[153518]: Connection terminated.
Dec 09 12:33:10 fedora NetworkManager[1234]: <warn>  [1670578390.0005] vpn[0x5639d9cb4710,70514b23-8b86-4599-86c4-536cdda1b37f,"pptp-vpn"]: dbus: failure: connect-failed (1)
Dec 09 12:33:10 fedora pppd[153518]: Exit.

My Windows laptop connects successfully.

Was it working fine before? Maybe something with the server

Dec 09 12:33:09 fedora pptp[153531]: nm-pptp-service-153511 log[ctrlp_disp:pptp_ctrl.c:976]: Call disconnect notification received (call id 19717)

Previously did not work, this is the first attempt to configure.
I can’t find the nf_conntrack_helper kernel module, I guess that’s the problem.