I can't actually see this module:
$ ls -l /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_* -rw-r--r-- 1 root root 203014 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack.ko -rw-r--r-- 1 root root 10518 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_amanda.ko -rw-r--r-- 1 root root 5070 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_broadcast.ko -rw-r--r-- 1 root root 26230 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_ftp.ko -rw-r--r-- 1 root root 100054 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_h323.ko -rw-r--r-- 1 root root 15934 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_irc.ko -rw-r--r-- 1 root root 6694 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_netbios_ns.ko -rw-r--r-- 1 root root 56158 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_netlink.ko -rw-r--r-- 1 root root 26334 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_pptp.ko -rw-r--r-- 1 root root 17062 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_proto_gre.ko -rw-r--r-- 1 root root 13446 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_sane.ko -rw-r--r-- 1 root root 41318 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_sip.ko -rw-r--r-- 1 root root 7238 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_snmp.ko -rw-r--r-- 1 root root 13726 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_conntrack_tftp.ko -rw-r--r-- 1 root root 5294 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_dup_netdev.ko -rw-r--r-- 1 root root 10214 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_log_common.ko -rw-r--r-- 1 root root 6670 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_log_netdev.ko -rw-r--r-- 1 root root 34838 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat.ko -rw-r--r-- 1 root root 7054 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_amanda.ko -rw-r--r-- 1 root root 9390 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_ftp.ko -rw-r--r-- 1 root root 8734 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_irc.ko -rw-r--r-- 1 root root 6102 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_redirect.ko -rw-r--r-- 1 root root 17438 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_sip.ko -rw-r--r-- 1 root root 6022 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_nat_tftp.ko -rw-r--r-- 1 root root 13662 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_synproxy_core.ko -rw-r--r-- 1 root root 125414 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_tables.ko -rw-r--r-- 1 root root 7854 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_tables_inet.ko -rw-r--r-- 1 root root 9862 May 6 16:59 /lib/modules/4.15.0-50-generic/kernel/net/netfilter/nf_tables_netdev.ko
I can't actually see this module:
$ ls -l /lib/modules/ 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_* 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ amanda. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ broadcast. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ ftp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ h323.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ irc.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ netbios_ ns.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ netlink. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ pptp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ proto_gre. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ sane.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ sip.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ snmp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_conntrack_ tftp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_dup_ netdev. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_log_ common. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_log_ netdev. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ amanda. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ ftp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ irc.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ redirect. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ sip.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_nat_ tftp.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_synproxy_ core.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_tables. ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_tables_ inet.ko 4.15.0- 50-generic/ kernel/ net/netfilter/ nf_tables_ netdev. ko
-rw-r--r-- 1 root root 203014 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 10518 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 5070 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 26230 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 100054 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 15934 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 6694 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 56158 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 26334 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 17062 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 13446 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 41318 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 7238 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 13726 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 5294 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 10214 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 6670 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 34838 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 7054 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 9390 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 8734 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 6102 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 17438 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 6022 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 13662 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 125414 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 7854 May 6 16:59 /lib/modules/
-rw-r--r-- 1 root root 9862 May 6 16:59 /lib/modules/