nf_nat_proto_gre module missing in kernel 4.18.0-240.22.1.el8_3.x86_64

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I can't make PPTP work over RHEL 8.3 with kernel 4.18.0-240.22.1.el8_3.x86_64 .
Apparently modules for GRE protocol are missing from kernel? nf_nat_proto_gre, nf_conntrack_proto_gre.
How can I add missing modules or connect PPTP client over NAT?
Any suggestions are greatly appreciated.


After many hours I found answer to my question. 1. grep CONFIG_NF_CT_PROTO_GRE /boot/config-$(uname -r) CONFIG_NF_CT_PROTO_GRE=y meaning the support is compiled to my kernel already, hence I have no module to load. 2. I could not find kernel config switch for CONFIG_NF_NAT_PROTO_GRE at all - it is apparently no longer present in this kernel version. 3. NAT support for GRE is available, but it starts to work only after sysctl net.netfilter.nf_conntrack_helper=1 Thanks to this post, where can also be found a suggestion how to make it survive reboot: