I cannot confirm this with the 5.8.0-12 kernel. Eg, with the 5.4 kernel in groovy, things work fine:
$ cat /proc/version_signature Ubuntu 5.4.0-42.46-generic 5.4.44 $ sudo modprobe iptable_filter $ sudo modprobe ip6table_filter $ lsmod|grep table_filter ip6table_filter 16384 0 ip6_tables 32768 1 ip6table_filter iptable_filter 16384 0 ip_tables 32768 1 iptable_filter x_tables 40960 4 ip6table_filter,iptable_filter,ip6_tables,ip_tables and booting into the current 5.8 kernel in groovy-proposed, it still works ok: $ cat /proc/version_signature Ubuntu 5.8.0-12.13-generic 5.8.0-rc7 $ lsmod|grep table_filter $ sudo modprobe iptable_filter $ sudo modprobe ip6table_filter $ lsmod|grep table_filter ip6table_filter 16384 0 ip6_tables 32768 1 ip6table_filter iptable_filter 16384 0 ip_tables 32768 1 iptable_filter x_tables 45056 4 ip6table_filter,iptable_filter,ip6_tables,ip_tables I upgraded to this kernel by using 'sudo apt-get install linux-generic'. Did you fetch all the necessary packages? Eg, in my non-secure-boot VM: ii linux-generic 5.8.0.12.14 amd64 Complete Generic Linux kernel and headers ii linux-headers-5.8.0-12 5.8.0-12.13 all Header files related to Linux kernel version 5.8.0 ii linux-headers-5.8.0-12-generic 5.8.0-12.13 amd64 Linux kernel headers for version 5.8.0 on 64 bit x86 SMP ii linux-headers-generic 5.8.0.12.14 amd64 Generic Linux kernel headers ii linux-image-5.8.0-12-generic 5.8.0-12.13 amd64 Signed kernel image generic ii linux-image-generic 5.8.0.12.14 amd64 Generic Linux kernel image ii linux-modules-5.8.0-12-generic 5.8.0-12.13 amd64 Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP ii linux-modules-extra-5.8.0-12-generic 5.8.0-12.13 amd64 Linux kernel extra modules for version 5.8.0 on 64 bit x86 SMP ** Changed in: linux (Ubuntu) Status: Confirmed => Incomplete -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1891020 Title: iptable_filter and ip6table_filter cannot be loaded with 5.8 kernel Status in linux package in Ubuntu: Incomplete Bug description: Ubuntu groovy linux-modules-5.8.0-12-generic 5.8.0-12.13 # uname -r 5.8.0-12-generic After reboot, 1) no IPv4 iptable kernel module are loaded: # lsmod|grep iptable # 2) all IPv4 iptable kernel modules are present: # find /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter -name "iptable_*" /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_filter.ko /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_nat.ko /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_mangle.ko /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_raw.ko /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_security.ko 3) No IPv4 iptable kernel modules can be loaded: # for module in iptable_filter iptable_nat iptable_mangle; do modprobe /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/${module}.ko; done modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_filter.ko not found in directory /lib/modules/5.8.0-12-generic modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_nat.ko not found in directory /lib/modules/5.8.0-12-generic modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_mangle.ko not found in directory /lib/modules/5.8.0-12-generic 4) Same issue after re-creating the module dependency: # depmod # for module in iptable_filter iptable_nat iptable_mangle; do modprobe /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/${module}.ko; done modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_filter.ko not found in directory /lib/modules/5.8.0-12-generic modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_nat.ko not found in directory /lib/modules/5.8.0-12-generic modprobe: FATAL: Module /lib/modules/5.8.0-12-generic/kernel/net/ipv4/netfilter/iptable_mangle.ko not found in directory /lib/modules/5.8.0-12-generic No such issue with linux-modules-5.4.0-42-generic. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1891020/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp