initial release

.gitignore

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+.idea/
+.vscode/
+cmd/dynafire/dynafire

README.md

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+dynafire - real-time threat detection for any Linux system
+=
+
+[Turris Sentinel](https://view.sentinel.turris.cz/?period=1w) is a real-time threat detection & attack prevention system from
+the creators of the [Turris](https://www.turris.com/en/) series of open-source routers, however this service is normally only available via the router interface.
+This makes it impractical to use the real-time data provided by Turris Sentinel on a VPS for example, which you cannot easily put behind a Turris router hardware.
+
+`dynafire` is a lightweight Linux daemon that lets any Linux system running the industry standard `firewalld` firewall update its firewall rules in real-time based on Sentinel data.
+
+Installation via package managers
+-
+TODO
+
+Manual installation
+-
+Because `dynafire` ships as a single binary, it is easy to install it manually on practically any `systemd`-based distro.
+
+Before proceeding please ensure that both `NetworkManager` and `firewalld` are installed and running:
+
+```shell
+$ sudo systemctl check NetworkManager                                   
+active
+
+$ sudo systemctl check firewalld                                   
+active
+```
+
+Download the binary:
+
+TODO
+
+Ensure the binary is executable:
+
+`$ chmod +x dynafire`
+
+Copy the binary to your `$PATH`:
+
+`$ sudo cp dynafire /usr/bin/`
+
+
+Next, download the `systemd` service definition file:
+
+TODO 
+
+Building from source
+-
+
+TODO
+
+Configuration
+-
+
+The `dynafire` configuration file is created upon first launch under `/etc/dynafire/config.json`.
+By default, it has the following values:
+
+```json
+{
+  "log_level": "INFO",
+  "zone_target_policy": "ACCEPT"
+}
+```
+
+The `log_level` can be set to `DEBUG` (most verbose), `INFO` and `ERROR` (least verbose).
+
+By default, the `dynafire` firewalld zone is set to `ACCEPT` every packet that is NOT on the Turris Sentinel blacklist, so as not to accidentally block legitimate traffic. 
+However, you can make this stricter by changing the `zone_target_policy` to i.e. `REJECT` or `DROP`, see [firewalld zone options](https://firewalld.org/documentation/zone/options.html) for details.  
+
+Contributing
+-
+Bug reports and pull requests are welcome. Do not hesitate to open a PR / file an issue or a feature request.

cmd/dynafire/main.go

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+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"sync"
+
+	"github.com/MatejLach/dynafire/firewall/firewalld"
+	"github.com/MatejLach/dynafire/provider/turris"
+)
+
+func main() {
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, nil)))
+
+	fwc, err := firewalld.New()
+	if err != nil {
+		slog.Error("Initialization failed; host system pre-requisites not met", "details", err)
+		os.Exit(1)
+	}
+
+	tc, err := turris.NewClient(turris.Url, turris.Port)
+	if err != nil {
+		slog.Error("Unable to initialize Turris dynafire client", "details", err)
+		os.Exit(1)
+	}
+
+	err = tc.Connect()
+	if err != nil {
+		slog.Error("Unable to connect to Turris firewall update server", "details", err)
+		os.Exit(1)
+	}
+
+	wg := sync.WaitGroup{}
+	sem := make(chan struct{}, 1)
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		tc.RequestMessages(context.Background())
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for listMsg := range tc.ListChan {
+			slog.Info(fmt.Sprintf("adding %d IPs to the blacklist", len(listMsg.Blacklist)))
+			sem <- struct{}{}
+
+			err = fwc.ResetFirewallRules()
+			if err != nil {
+				slog.Error("unable to clear old IP blacklist", "details", err)
+				os.Exit(1)
+			}
+
+			err = fwc.BlockIPList(listMsg.Blacklist)
+			if err != nil {
+				slog.Error("unable to initialize IP blacklist", "details", err)
+				os.Exit(1)
+			}
+			slog.Info("Starting to process delta updates...")
+			<-sem
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		for deltaMsg := range tc.DeltaChan {
+			sem <- struct{}{}
+
+			// 'positive' operation adds an IP to the blacklist
+			// 'negative' removes an existing IP from the blacklist
+			switch deltaMsg.Operation {
+			case "positive":
+				err = fwc.BlockIP(deltaMsg.IP)
+				if err != nil {
+					slog.Error("unable to blacklist IP", "details", err)
+					os.Exit(1)
+				}
+
+				slog.Debug("blacklisting", "IP", deltaMsg.IP.String())
+			case "negative":
+				err = fwc.UnblockIP(deltaMsg.IP)
+				if err != nil {
+					slog.Error("unable to whitelist IP", "details", err)
+					os.Exit(1)
+				}
+
+				slog.Debug("whitelisting", "IP", deltaMsg.IP.String())
+			}
+			<-sem
+		}
+	}()
+
+	wg.Wait()
+}

dist/systemd/dynafire.service

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+[Unit]
+Description=dynafire - real-time threat detection for any Linux system
+After=network.target
+
+[Install]
+WantedBy=multi-user.target
+
+[Service]
+User=root
+Type=simple
+ExecStart="/usr/bin/dynafire"
+TimeoutStopSec=20
+KillMode=process
+Restart=on-failure

firewall/blocker.go

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+package firewall
+
+import "net"
+
+type Blocker interface {
+	BlockIP(address net.IP) error
+	BlockIPList(blacklist []net.IP) error
+	UnblockIP(address net.IP) error
+	ResetFirewallRules() error
+}

firewall/firewalld/config.go

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+package firewalld
+
+import (
+	"encoding/json"
+	"log/slog"
+	"os"
+	"strings"
+)
+
+type Config struct {
+	LogLevel         string `json:"log_level"`
+	ZoneTargetPolicy string `json:"zone_target_policy"`
+}
+
+func initConfig() {
+	slog.Info("No config.json found, creating new config...")
+	config := Config{
+		LogLevel:         "INFO",
+		ZoneTargetPolicy: "ACCEPT",
+	}
+
+	jsonBytes, err := json.MarshalIndent(config, "", "    ")
+	if err != nil {
+		slog.Error("unable to parse config file", "details", err)
+		os.Exit(1)
+	}
+
+	err = os.MkdirAll("/etc/dynafire", 0775)
+	if err != nil {
+		slog.Error("unable to make config directory", "details", err)
+		os.Exit(1)
+	}
+
+	err = os.WriteFile("/etc/dynafire/config.json", jsonBytes, 0775)
+	if err != nil {
+		slog.Error("unable to save default config file", "details", err)
+		os.Exit(1)
+	}
+
+	slog.Info("New config.json created, feel free to modify the defaults, then restart for your changes to take effect.")
+}
+
+func parseConfig() (Config, error) {
+	var config Config
+	cfgData, err := os.ReadFile("/etc/dynafire/config.json")
+	if err != nil {
+		return Config{}, err
+	}
+
+	err = json.Unmarshal(cfgData, &config)
+	if err != nil {
+		return Config{}, err
+	}
+
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: parseLogLevel(config.LogLevel)})))
+
+	return config, nil
+}
+
+func configExists() bool {
+	if _, err := os.Stat("/etc/dynafire/config.json"); os.IsNotExist(err) {
+		return false
+	}
+
+	return true
+}
+
+func parseLogLevel(level string) slog.Level {
+	switch strings.ToUpper(level) {
+	case "DEBUG":
+		return slog.LevelDebug
+	case "INFO":
+		return slog.LevelInfo
+	case "ERROR":
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}