Use custom sysctl

Signed-off-by: Tommy <contact@tommytran.io>

etc/sysctl.d/99-server.conf

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+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+dev.tty.ldisc_autoload = 0
+
+# https://access.redhat.com/solutions/1985633
+# Seems dangerous
+fs.binfmt_misc.status = 0
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-userspace
+# Enable fs.protected sysctls
+fs.protected_regular = 2
+fs.protected_fifos = 2
+fs.protected_symlinks = 1
+fs.protected_hardlinks = 1
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#core-dumps
+# Disable coredumps
+# For additional safety, disable coredumps using ulimit and systemd too.
+kernel.core_pattern=|/bin/false
+fs.suid_dumpable = 0
+
+# Restrict dmesg to CAP_SYS_LOG
+# https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
+kernel.dmesg_restrict = 1
+
+# https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-kernel
+# https://kernsec.org/wiki/index.php/Bug_Classes/Kernel_pointer_leak
+# Restrict access to /proc
+kernel.kptr_restrict = 2
+
+# Not needed, I don't do livepatching and reboot regularly.
+# On Ubuntu LTS just sed this to be 0 if you use livepatch.
+kernel.kexec_load_disabled = 1
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+# Basically, restrict eBPF to CAP_BPF.
+kernel.unprivileged_bpf_disabled = 1
+net.core.bpf_jit_harden = 2
+
+# Docker running as root do not require unpriv user ns, which is dangerous, so we disabe it
+kernel.unprivileged_userns_clone = 0
+
+# Needed for gVisor, which is used on almost all of my servers
+kernel.yama.ptrace_scope = 1
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+# Restrict performance events from unprivileged users as much as possible.
+# We are using 4 here, since Ubuntu supports such a level.
+# Official Linux kernel documentation only says >= so it probably will work.
+kernel.perf_event_paranoid = 4
+
+# https://github.com/containerd/containerd/issues/9048
+# Disable io_uring, a very sus feature.
+# Note that this will make using Proxmox extremely annoying though, so you might wanna comment this out
+# on a Proxmox node.
+kernel_io_uring_disable = 2
+
+# https://www.stigviewer.com/stig/red_hat_enterprise_linux_6/2020-09-03/finding/V-217911
+# Not running a router here, so no redirects
+net.ipv4.conf.*.send_redirects = 0
+net.ipv4.conf.*.accept_redirects = 0
+net.ipv6.conf.*.accept_redirects = 0
+
+# Check if the source of the IP address is reachable through the same interface it came in
+# Basic IP spoofing mitigation
+net.ipv4.conf.*.rp_filter=1
+
+# Respond to ICMP
+net.ipv4.icmp_echo_ignore_all=1
+net.ipv6.icmp.echo_ignore_all=1
+
+# Enable IP Forwarding
+# Almost all of my servers run Docker anyways, and Docker absolutely requires this.
+net.ipv4.ip_forward = 1
+net.ipv6.conf.all.forwarding = 1
+
+# https://www.stigviewer.com/stig/red_hat_enterprise_linux_6/2016-06-05/finding/V-38537
+# Ignore bogus icmp response
+net.ipv4.icmp_ignore_bogus_error_responses = 1
+
+# Protection against time-wait assasination attacks
+net.ipv4.tcp_rfc1337 = 1
+
+# Enable SYN cookies
+# Basic SYN flood mitigation
+net.ipv4.tcp_syncookies = 1 
+
+# https://access.redhat.com/sites/default/files/attachments/20150325_network_performance_tuning.pdf
+# Make sure TCP timestamp is enabled
+net.ipv4.tcp_timestamps = 1
+
+# https://access.redhat.com/sites/default/files/attachments/20150325_network_performance_tuning.pdf
+# Disable TCP SACK
+# We have good networking :)
+net.ipv4.tcp_sack = 0
+
+# No SACK, therefore no Duplicated SACK
+net.ipv4.tcp_dsack = 0
+
+# Improve ALSR effectiveness for mmap
+vm.mmap_rnd_bits = 32
+vm.mmap_rnd_compat_bits = 16
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-kernel
+# Restrict userfaultfd to CAP_SYS_PTRACE
+# https://bugs.archlinux.org/task/62780
+# Interestingly enough, Arch does not even have userfaultfd in their kernel, so it is
+# probably not used in the real world at all.
+vm.unprivileged_userfaultfd = 0

etc/sysctl.d/99-workstation.conf

@@ -0,0 +1,110 @@
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+dev.tty.ldisc_autoload = 0
+
+# https://access.redhat.com/solutions/1985633
+# Seems dangerous
+fs.binfmt_misc.status = 0
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-userspace
+# Enable fs.protected sysctls
+fs.protected_regular = 2
+fs.protected_fifos = 2
+fs.protected_symlinks = 1
+fs.protected_hardlinks = 1
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#core-dumps
+# Disable coredumps
+# For additional safety, disable coredumps using ulimit and systemd too.
+kernel.core_pattern=|/bin/false
+fs.suid_dumpable = 0
+
+# Restrict dmesg to CAP_SYS_LOG
+# https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
+kernel.dmesg_restrict = 1
+
+# https://www.kernel.org/doc/Documentation/sysctl/kernel.txt
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-kernel
+# https://kernsec.org/wiki/index.php/Bug_Classes/Kernel_pointer_leak
+# Restrict access to /proc
+kernel.kptr_restrict = 2
+
+# Not needed, I don't do livepatching and reboot regularly.
+# On a workstation, this shouldn't be used at all. Don't live patch, just reboot.
+kernel.kexec_load_disabled = 1
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+# Basically, restrict eBPF to CAP_BPF.
+kernel.unprivileged_bpf_disabled = 1
+net.core.bpf_jit_harden = 2
+
+# Needed for Flatpak and Bubblewrap
+kernel.unprivileged_userns_clone = 1
+
+# Disable ptrace. Not needed on workstations.
+kernel.yama.ptrace_scope = 3
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl
+# Restrict performance events from unprivileged users as much as possible.
+# We are using 4 here, since Ubuntu supports such a level.
+# Official Linux kernel documentation only says >= so it probably will work.
+kernel.perf_event_paranoid = 4
+
+# https://github.com/containerd/containerd/issues/9048
+# Disable io_uring, a very sus feature.
+# Note that this will make using Proxmox extremely annoying though, so you might wanna comment this out
+# on a Proxmox node.
+kernel_io_uring_disable = 2
+
+# https://www.stigviewer.com/stig/red_hat_enterprise_linux_6/2020-09-03/finding/V-217911
+# Not running a router here, so no redirects
+net.ipv4.conf.*.send_redirects = 0
+net.ipv4.conf.*.accept_redirects = 0
+net.ipv6.conf.*.accept_redirects = 0
+
+# Check if the source of the IP address is reachable through the same interface it came in
+# Basic IP spoofing mitigation
+net.ipv4.conf.*.rp_filter=1
+
+# Do not respond to ICMP
+net.ipv4.icmp_echo_ignore_all=1
+net.ipv6.icmp.echo_ignore_all=1
+
+# Enable IP Forwarding
+# Needed for VM networking and whatnot.
+net.ipv4.ip_forward = 1
+net.ipv6.conf.all.forwarding = 1
+
+# https://www.stigviewer.com/stig/red_hat_enterprise_linux_6/2016-06-05/finding/V-38537
+# Ignore bogus icmp response
+net.ipv4.icmp_ignore_bogus_error_responses = 1
+
+# Protection against time-wait assasination attacks
+net.ipv4.tcp_rfc1337 = 1
+
+# Enable SYN cookies
+# Basic SYN flood mitigation
+net.ipv4.tcp_syncookies = 1 
+
+# https://access.redhat.com/sites/default/files/attachments/20150325_network_performance_tuning.pdf
+# Make sure TCP timestamp is enabled
+net.ipv4.tcp_timestamps = 1
+
+# https://access.redhat.com/sites/default/files/attachments/20150325_network_performance_tuning.pdf
+# Disable TCP SACK
+# We have good networking :)
+net.ipv4.tcp_sack = 0
+
+# No SACK, therefore no Duplicated SACK
+net.ipv4.tcp_dsack = 0
+
+# Improve ALSR effectiveness for mmap
+vm.mmap_rnd_bits = 32
+vm.mmap_rnd_compat_bits = 16
+
+# https://madaidans-insecurities.github.io/guides/linux-hardening.html#sysctl-kernel
+# Restrict userfaultfd to CAP_SYS_PTRACE
+# https://bugs.archlinux.org/task/62780
+# Interestingly enough, Arch does not even have userfaultfd in their kernel, so it is
+# probably not used in the real world at all.
+vm.unprivileged_userfaultfd = 0

etc/systemd/coredump.conf.d/disable.conf

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+[Coredump]
+Storage=none