rotuer: use firewallgen to make packet filter rules
This commit is contained in:
Daniel Barlow
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d79a1e15bb
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b002a94e07
2 changed files with 133 additions and 1 deletions
124
examples/rotuer-firewall.nix
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124
examples/rotuer-firewall.nix
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let
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drop = expr : "${expr} drop";
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accept = expr : "${expr} accept";
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mcast-scope = 8;
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allow-incoming = false;
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bogons-ip6 = {
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type = "filter";
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family = "ip6";
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rules = [
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(drop "ip6 saddr ff00::/8") # multicast saddr is illegal
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(drop "ip6 saddr ::/128") # unspecified address
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(drop "ip6 daddr ::/128")
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(drop "ip6 saddr 2001:db8::/32") # documentation addresses
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(drop "ip6 daddr 2001:db8::/32")
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# I think this means "check FIB for (saddr, iif) to see if we
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# could route a packet to that address using that interface",
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# and if we can't then it was an inapproppriate source address
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# for packets received _from_ said interface
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(drop "fib saddr . iif oif eq 0")
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(drop "icmpv6 type router-renumbering")
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(drop "icmpv6 type 139") # Node Information Query
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(drop "icmpv6 type 140") # Node Information Response
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(drop "icmpv6 type 100")
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(drop "icmpv6 type 101")
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(drop "icmpv6 type 200")
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(drop "icmpv6 type 201")
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(drop "icmpv6 type 127")
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(drop "icmpv6 type 255")
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(drop "icmpv6 type destination-unreachable ct state invalid,untracked")
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];
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};
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forward-ip6 = {
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type = "filter";
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family = "ip6";
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policy = "drop";
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hook = "forward";
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rules = [
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"jump bogons-ip6"
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(drop "ip6 saddr ::1/128") # loopback address [RFC4291]
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(drop "ip6 daddr ::1/128")
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(drop "ip6 saddr ::FFFF:0:0/96")# IPv4-mapped addresses
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(drop "ip6 daddr ::FFFF:0:0/96")
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(drop "ip6 saddr fe80::/10") # link-local unicast
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(drop "ip6 daddr fe80::/10")
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(drop "ip6 saddr fc00::/7") # unique-local addresses
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(drop "ip6 daddr fc00::/7")
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(drop "ip6 saddr 2001:10::/28") # ORCHID [RFC4843].
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(drop "ip6 daddr 2001:10::/28")
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(drop "ip6 saddr fc00::/7") # unique local source
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(drop "ip6 daddr fc00::/7") # and/or dst addresses [RFC4193]
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# multicast with wrong scopes
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(drop
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# dest addr first byte 0xff, low nibble of second byte <= scope
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# https://www.mankier.com/8/nft#Payload_Expressions-Raw_Payload_Expression
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"@nh,192,8 eq 0xff @nh,204,4 le ${toString mcast-scope}")
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(accept "oifname \"int\" iifname \"ppp0\" meta l4proto udp ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" meta l4proto udp")
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(accept "meta l4proto icmpv6")
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(accept "meta l4proto ah")
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(accept "meta l4proto esp")
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# does this ever get used or does the preceding general udp accept
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# already grab anything that might get here?
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(accept "oifname \"ppp0\" udp dport 500") # IKE Protocol [RFC5996]. haha zyxel
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(accept "ip6 nexthdr hip")
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## FIXME no support yet for recs 27-30 Mobility Header
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(accept "oifname \"int\" iifname \"ppp0\" meta l4proto tcp ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" meta l4proto tcp")
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(accept "oifname \"int\" iifname \"ppp0\" meta l4proto sctp ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" meta l4proto sctp")
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(accept "oifname \"int\" iifname \"ppp0\" meta l4proto dccp ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" meta l4proto dccp")
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# we can allow all reasonable inbound, or we can use an explicit
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# allowlist to enumerate the endpoints that are allowed to
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# accept inbound from the WAN
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(if allow-incoming
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then accept "oifname \"int\" iifname \"ppp0\""
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else "oifname \"int\" iifname \"ppp0\" jump incoming-allowed-ip6"
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)
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# allow all outbound and any inbound that's part of a
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# recognised (outbound-initiated) flow
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(accept "oifname \"int\" iifname \"ppp0\" ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" ")
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];
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};
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input-ip6 = {
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type = "filter";
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family = "ip6";
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policy = "drop";
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hook = "input";
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rules = [
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"jump bogons-ip6"
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(accept "meta l4proto icmpv6")
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(if allow-incoming
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then accept "oifname \"int\" iifname \"ppp0\""
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else "oifname \"int\" iifname \"ppp0\" jump incoming-allowed-ip6"
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)
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(accept "oifname \"int\" iifname \"ppp0\" ct state established,related")
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(accept "iifname \"int\" oifname \"ppp0\" ")
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];
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};
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incoming-allowed-ip6 = {
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type = "filter";
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family = "ip6";
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rules = [
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"oifname \"int\" ip6 daddr 2001:8b0:de3a:40de::e9d tcp dport 22"
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];
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};
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in {
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inherit input-ip6 forward-ip6 bogons-ip6 incoming-allowed-ip6;
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}
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@ -226,15 +226,23 @@ in rec {
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dependencies = [ services.wan ];
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};
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services.firewall =
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let config = pkgs.firewallgen "firewall.nft" (import ./rotuer-firewall.nix);
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in oneshot {
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name = "firewall";
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up = config;
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down = "${pkgs.nftables}/bin/nft flush ruleset";
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};
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services.packet_forwarding =
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let filename = "/proc/sys/net/ipv4/conf/all/forwarding";
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in oneshot {
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name = "let-the-ip-flow";
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up = ''
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${pkgs.nftables}/bin/nft -f ${../nat.nft}
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echo 1 > ${filename}
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'';
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down = "echo 0 > ${filename}";
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dependencies = [ services.firewall ];
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};
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services.dhcp6 =
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