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Add Connector
1 parent eb81b40 commit eb67752

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‎README.md‎

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@@ -63,4 +63,11 @@ type = tcp
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local_ip = 127.0.0.1
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local_port = 22
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remote_port = 2200
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```
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Connector:
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```
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sudo ./connector
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-s http[s]://[<user>:<pass>@]<server host>:<server port> # Server API
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[-i <interval>] # Update Interval, default 300s
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```

‎cmd/connector/main.go‎

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package main
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import (
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"encoding/json"
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"fmt"
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"io"
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"log"
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"net"
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"net/http"
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"net/url"
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"os"
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"os/signal"
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"syscall"
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"time"
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"github.com/Max-Sum/fcbreak"
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"github.com/akamensky/argparse"
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"github.com/coreos/go-iptables/iptables"
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)
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var (
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TempChainName = "FCBREAK-CONNECTOR-TEMP"
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ChainName = "FCBREAK-CONNECTOR"
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)
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func main() {
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parser := argparse.NewParser("fcbreak-connector", "Retrive address and write to iptables, Linux only currently")
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// Create string flag
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server := parser.String("s", "server", &argparse.Options{Required: true, Help: "Server Address, including protocol and user/pass"})
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interval := parser.Int("i", "interval", &argparse.Options{Default: 300, Help: "Interval between updates in seconds"})
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// Parse input
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err := parser.Parse(os.Args)
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if err != nil {
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// In case of error print error and print usage
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// This can also be done by passing -h or --help flags
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fmt.Print(parser.Usage(err))
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os.Exit(1)
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}
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serverUrl, err := url.Parse(*server)
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if err != nil {
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log.Printf("Failed to parse server URL: %v\n", err)
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}
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serverHostname := serverUrl.Hostname()
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// Gracefully Stop
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sigc := make(chan os.Signal, 1)
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signal.Notify(sigc,
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syscall.SIGHUP,
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syscall.SIGINT,
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syscall.SIGTERM,
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syscall.SIGQUIT)
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for {
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svcs, err := RefreshServices(*server)
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if err != nil {
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return
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}
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err = UpdateIPTables(svcs, serverHostname)
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if err != nil {
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log.Printf("Update iptables error: %v\n", err)
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}
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select {
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case <-time.After(time.Duration(*interval) * time.Second):
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svcs, err = RefreshServices(*server)
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if err != nil {
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return
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}
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err = UpdateIPTables(svcs, serverHostname)
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if err != nil {
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log.Printf("Update iptables error: %v\n", err)
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}
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case <-sigc:
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ClearIPTables()
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return
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}
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}
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}
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func RefreshServices(server string) (map[string]*fcbreak.ServiceInfo, error) {
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svcs := make(map[string]*fcbreak.ServiceInfo)
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addr := fmt.Sprintf("%s/services", server)
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req, err := http.NewRequest("GET", addr, nil)
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if err != nil {
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log.Printf("HTTP new request error: %v\n", err)
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return svcs, err
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}
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// Update svcs
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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log.Printf("HTTP Get error: %v\n", err)
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return svcs, err
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}
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by, err := io.ReadAll(resp.Body)
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if err != nil {
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log.Printf("HTTP Body error: %v\n", err)
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return svcs, err
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}
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resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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log.Printf("HTTP error: %s\n", string(by))
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return svcs, err
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}
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if err := json.Unmarshal(by, &svcs); err != nil {
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log.Printf("JSON parsing: %v\n", err)
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return svcs, err
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}
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log.Println("Successfully retrieve services.")
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return svcs, nil
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}
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func UpdateIPTables(svcs map[string]*fcbreak.ServiceInfo, serverHostname string) error {
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// Server IP
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ips, err := net.LookupIP(serverHostname)
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if err != nil {
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return err
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}
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// Update iptables
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ipt, err := iptables.New(iptables.IPFamily(iptables.ProtocolIPv4))
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if err != nil {
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log.Fatalf("Failed to new up an IPtables intance: %v", err)
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}
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if exists, err := ipt.ChainExists("nat", "OUTPUT"); !exists || err != nil {
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log.Fatalf("iptables nat OUTPUT chain doesn't exists, possibly a permission problem.")
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}
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if exists, err := ipt.ChainExists("nat", "PREROUTING"); !exists || err != nil {
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log.Fatalf("iptables nat PREROUTING chain doesn't exists, possibly a permission problem.")
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}
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// Write in Temp chain
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if err = ipt.NewChain("nat", TempChainName); err != nil {
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return err
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}
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defer ipt.ClearAndDeleteChain("nat", TempChainName)
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for name, svc := range svcs {
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remote_ip, remote_port, err := net.SplitHostPort(svc.RemoteAddr)
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if err != nil {
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return err
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}
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// IPv4 only now
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if remote_ip == "" || remote_ip == "0.0.0.0" || remote_ip == "[::]" {
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for _, ip := range ips {
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ipv4 := ip.To4()
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if ipv4 == nil {
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continue
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}
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err = ipt.AppendUnique("nat", TempChainName, "-p", "tcp", "-d", ipv4.String(), "--dport", remote_port, "-j", "DNAT", "--to-destination", svc.ExposedAddr)
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if err != nil {
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return err
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}
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}
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} else {
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err = ipt.AppendUnique("nat", TempChainName, "-p", "tcp", "-d", remote_ip, "--dport", remote_port, "-j", "DNAT", "--to-destination", svc.ExposedAddr)
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if err != nil {
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return err
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}
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}
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log.Printf("Successfully Update Service [%s]\n", name)
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}
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// Replace Old Chain
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exists, err := ipt.ChainExists("nat", ChainName)
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if err != nil {
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return err
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}
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if exists {
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if err = ipt.ClearAndDeleteChain("nat", ChainName); err != nil {
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return err
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}
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}
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if err = ipt.RenameChain("nat", TempChainName, ChainName); err != nil {
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return err
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}
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// Direct flow
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if err = ipt.AppendUnique("nat", "PREROUTING", "-j", ChainName); err != nil {
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return err
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}
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if err = ipt.AppendUnique("nat", "OUTPUT", "-j", ChainName); err != nil {
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return err
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}
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return nil
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}
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func ClearIPTables() {
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// Update iptables
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ipt, err := iptables.New(iptables.IPFamily(iptables.ProtocolIPv4))
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if err != nil {
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log.Fatalf("Failed to new up an IPtables intance: %v", err)
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}
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ipt.DeleteIfExists("nat", "OUTPUT", "-j", ChainName)
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ipt.DeleteIfExists("nat", "PREROUTING", "-j", ChainName)
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exists, _ := ipt.ChainExists("nat", ChainName)
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if exists {
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ipt.ClearAndDeleteChain("nat", ChainName)
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}
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exists, _ = ipt.ChainExists("nat", TempChainName)
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if exists {
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ipt.ClearAndDeleteChain("nat", TempChainName)
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}
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}

‎go.mod‎

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@@ -12,6 +12,7 @@ require (
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)
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require (
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github.com/coreos/go-iptables v0.6.0 // indirect
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github.com/gin-contrib/sse v0.1.0 // indirect
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github.com/go-playground/locales v0.14.0 // indirect
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github.com/go-playground/universal-translator v0.18.0 // indirect

‎go.sum‎

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github.com/akamensky/argparse v1.3.1 h1:kP6+OyvR0fuBH6UhbE6yh/nskrDEIQgEA1SUXDPjx4g=
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github.com/akamensky/argparse v1.3.1/go.mod h1:S5kwC7IuDcEr5VeXtGPRVZ5o/FdhcMlQz4IZQuw64xA=
3+
github.com/coreos/go-iptables v0.6.0 h1:is9qnZMPYjLd8LYqmm/qlE+wwEgJIkTYdhV3rfZo4jk=
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github.com/coreos/go-iptables v0.6.0/go.mod h1:Qe8Bv2Xik5FyTXwgIbLAnv2sWSBmvWdFETJConOQ//Q=
35
github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
46
github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
57
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

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