75 lines
2.4 KiB
Nix
75 lines
2.4 KiB
Nix
# security tweaks borrowed from @hlissner
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{
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boot.kernel.sysctl = {
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# The Magic SysRq key is a key combo that allows users connected to the
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# system console of a Linux kernel to perform some low-level commands.
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# Disable it, since we don't need it, and is a potential security concern.
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"kernel.sysrq" = 0;
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## TCP hardening
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# Prevent bogus ICMP errors from filling up logs.
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"net.ipv4.icmp_ignore_bogus_error_responses" = 1;
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# Reverse path filtering causes the kernel to do source validation of
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# packets received from all interfaces. This can mitigate IP spoofing.
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"net.ipv4.conf.default.rp_filter" = 1;
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"net.ipv4.conf.all.rp_filter" = 1;
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# Do not accept IP source route packets (we're not a router)
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"net.ipv4.conf.all.accept_source_route" = 0;
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"net.ipv6.conf.all.accept_source_route" = 0;
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# Don't send ICMP redirects (again, we're on a router)
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"net.ipv4.conf.all.send_redirects" = 0;
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"net.ipv4.conf.default.send_redirects" = 0;
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# Refuse ICMP redirects (MITM mitigations)
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"net.ipv4.conf.all.accept_redirects" = 0;
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"net.ipv4.conf.default.accept_redirects" = 0;
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"net.ipv4.conf.all.secure_redirects" = 0;
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"net.ipv4.conf.default.secure_redirects" = 0;
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"net.ipv6.conf.all.accept_redirects" = 0;
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"net.ipv6.conf.default.accept_redirects" = 0;
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# Protects against SYN flood attacks
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"net.ipv4.tcp_syncookies" = 1;
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# Incomplete protection again TIME-WAIT assassination
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"net.ipv4.tcp_rfc1337" = 1;
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## TCP optimization
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# TCP Fast Open is a TCP extension that reduces network latency by packing
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# data in the sender’s initial TCP SYN. Setting 3 = enable TCP Fast Open for
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# both incoming and outgoing connections:
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"net.ipv4.tcp_fastopen" = 3;
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# Bufferbloat mitigations + slight improvement in throughput & latency
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"net.ipv4.tcp_congestion_control" = "bbr";
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"net.core.default_qdisc" = "cake";
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};
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boot.kernelModules = ["tcp_bbr"];
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services.openssh.settings.LogLevel = "VERBOSE";
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security.acme = {
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acceptTerms = true;
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defaults.email = "github@notohh.dev";
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};
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services.fail2ban = {
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enable = true;
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bantime = "1h";
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maxretry = 1;
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ignoreIP = [
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"192.168.0.0/16"
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"172.16.0.0/12"
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"10.0.0.0/8"
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"5.161.102.107/32"
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"100.71.49.65/10"
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"100.82.146.40/10"
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];
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jails = {
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DEFAULT = {
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settings = {
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findtime = 100000;
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mode = "aggressive";
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};
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};
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};
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};
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}
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