[client] Add firewall rules to the debug bundle (#3089)

Adds the following to the debug bundle:
- iptables: `iptables-save`, `iptables -v -n -L`
- nftables: `nft list ruleset` or if not available formatted output from netlink (WIP)

client/server/debug_test.go

@@ -428,3 +428,116 @@ func isInCGNATRange(ip net.IP) bool {
 	}
 	return cgnat.Contains(ip)
 }
+
+func TestAnonymizeFirewallRules(t *testing.T) {
+	// TODO: Add ipv6
+
+	// Example iptables-save output
+	iptablesSave := `# Generated by iptables-save v1.8.7 on Thu Dec 19 10:00:00 2024
+*filter
+:INPUT ACCEPT [0:0]
+:FORWARD ACCEPT [0:0]
+:OUTPUT ACCEPT [0:0]
+-A INPUT -s 192.168.1.0/24 -j ACCEPT
+-A INPUT -s 44.192.140.1/32 -j DROP
+-A FORWARD -s 10.0.0.0/8 -j DROP
+-A FORWARD -s 44.192.140.0/24 -d 52.84.12.34/24 -j ACCEPT
+COMMIT
+
+*nat
+:PREROUTING ACCEPT [0:0]
+:INPUT ACCEPT [0:0]
+:OUTPUT ACCEPT [0:0]
+:POSTROUTING ACCEPT [0:0]
+-A POSTROUTING -s 192.168.100.0/24 -j MASQUERADE
+-A PREROUTING -d 44.192.140.10/32 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.1.10:80
+COMMIT`
+
+	// Example iptables -v -n -L output
+	iptablesVerbose := `Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
+    pkts bytes target     prot opt in     out     source               destination         
+       0     0 ACCEPT     all  --  *      *       192.168.1.0/24       0.0.0.0/0           
+     100  1024 DROP       all  --  *      *       44.192.140.1         0.0.0.0/0
+
+Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
+    pkts bytes target     prot opt in     out     source               destination         
+       0     0 DROP       all  --  *      *       10.0.0.0/8           0.0.0.0/0           
+      25   256 ACCEPT     all  --  *      *       44.192.140.0/24      52.84.12.34/24
+
+Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
+    pkts bytes target     prot opt in     out     source               destination`
+
+	// Example nftables output
+	nftablesRules := `table inet filter {
+        chain input {
+                type filter hook input priority filter; policy accept;
+                ip saddr 192.168.1.1 accept
+                ip saddr 44.192.140.1 drop
+        }
+        chain forward {
+                type filter hook forward priority filter; policy accept;
+                ip saddr 10.0.0.0/8 drop
+                ip saddr 44.192.140.0/24 ip daddr 52.84.12.34/24 accept
+        }
+    }`
+
+	anonymizer := anonymize.NewAnonymizer(anonymize.DefaultAddresses())
+
+	// Test iptables-save anonymization
+	anonIptablesSave := anonymizer.AnonymizeString(iptablesSave)
+
+	// Private IP addresses should remain unchanged
+	assert.Contains(t, anonIptablesSave, "192.168.1.0/24")
+	assert.Contains(t, anonIptablesSave, "10.0.0.0/8")
+	assert.Contains(t, anonIptablesSave, "192.168.100.0/24")
+	assert.Contains(t, anonIptablesSave, "192.168.1.10")
+
+	// Public IP addresses should be anonymized to the default range
+	assert.NotContains(t, anonIptablesSave, "44.192.140.1")
+	assert.NotContains(t, anonIptablesSave, "44.192.140.0/24")
+	assert.NotContains(t, anonIptablesSave, "52.84.12.34")
+	assert.Contains(t, anonIptablesSave, "198.51.100.") // Default anonymous range
+
+	// Structure should be preserved
+	assert.Contains(t, anonIptablesSave, "*filter")
+	assert.Contains(t, anonIptablesSave, ":INPUT ACCEPT [0:0]")
+	assert.Contains(t, anonIptablesSave, "COMMIT")
+	assert.Contains(t, anonIptablesSave, "-j MASQUERADE")
+	assert.Contains(t, anonIptablesSave, "--dport 80")
+
+	// Test iptables verbose output anonymization
+	anonIptablesVerbose := anonymizer.AnonymizeString(iptablesVerbose)
+
+	// Private IP addresses should remain unchanged
+	assert.Contains(t, anonIptablesVerbose, "192.168.1.0/24")
+	assert.Contains(t, anonIptablesVerbose, "10.0.0.0/8")
+
+	// Public IP addresses should be anonymized to the default range
+	assert.NotContains(t, anonIptablesVerbose, "44.192.140.1")
+	assert.NotContains(t, anonIptablesVerbose, "44.192.140.0/24")
+	assert.NotContains(t, anonIptablesVerbose, "52.84.12.34")
+	assert.Contains(t, anonIptablesVerbose, "198.51.100.") // Default anonymous range
+
+	// Structure and counters should be preserved
+	assert.Contains(t, anonIptablesVerbose, "Chain INPUT (policy ACCEPT 0 packets, 0 bytes)")
+	assert.Contains(t, anonIptablesVerbose, "100  1024 DROP")
+	assert.Contains(t, anonIptablesVerbose, "pkts bytes target")
+
+	// Test nftables anonymization
+	anonNftables := anonymizer.AnonymizeString(nftablesRules)
+
+	// Private IP addresses should remain unchanged
+	assert.Contains(t, anonNftables, "192.168.1.1")
+	assert.Contains(t, anonNftables, "10.0.0.0/8")
+
+	// Public IP addresses should be anonymized to the default range
+	assert.NotContains(t, anonNftables, "44.192.140.1")
+	assert.NotContains(t, anonNftables, "44.192.140.0/24")
+	assert.NotContains(t, anonNftables, "52.84.12.34")
+	assert.Contains(t, anonNftables, "198.51.100.") // Default anonymous range
+
+	// Structure should be preserved
+	assert.Contains(t, anonNftables, "table inet filter {")
+	assert.Contains(t, anonNftables, "chain input {")
+	assert.Contains(t, anonNftables, "type filter hook input priority filter; policy accept;")
+}