func setupIPMasq(ipn ip.IP4Net) error {
ipt, err := iptables.New()
if err != nil {
return fmt.Errorf("failed to setup IP Masquerade. iptables was not found")
}
err = ipt.ClearChain("nat", "FLANNEL")
if err != nil {
return fmt.Errorf("Failed to create/clear FLANNEL chain in NAT table: %v", err)
}
rules := [][]string{
// This rule makes sure we don't NAT traffic within overlay network (e.g. coming out of docker0)
{"FLANNEL", "-d", ipn.String(), "-j", "ACCEPT"},
// NAT if it's not multicast traffic
{"FLANNEL", "!", "-d", "224.0.0.0/4", "-j", "MASQUERADE"},
// This rule will take everything coming from overlay and send it to FLANNEL chain
{"POSTROUTING", "-s", ipn.String(), "-j", "FLANNEL"},
// Masquerade anything headed towards flannel from the host
{"POSTROUTING", "!", "-s", ipn.String(), "-d", ipn.String(), "-j", "MASQUERADE"},
}
for _, rule := range rules {
log.Info("Adding iptables rule: ", strings.Join(rule, " "))
chain := rule[0]
args := rule[1:len(rule)]
err = ipt.AppendUnique("nat", chain, args...)
if err != nil {
return fmt.Errorf("Failed to insert IP masquerade rule: %v", err)
}
}
return nil
}
func teardownIPMasq(ipn ip.IP4Net) error {
ipt, err := iptables.New()
if err != nil {
return fmt.Errorf("failed to teardown IP Masquerade. iptables was not found")
}
for _, rule := range rules(ipn) {
log.Info("Deleting iptables rule: ", strings.Join(rule, " "))
err = ipt.Delete("nat", "POSTROUTING", rule...)
if err != nil {
return fmt.Errorf("failed to delete IP masquerade rule: %v", err)
}
}
return nil
}
func setupIPMasq(ipn ip.IP4Net) error {
ipt, err := iptables.New()
if err != nil {
return fmt.Errorf("failed to set up IP Masquerade. iptables was not found")
}
for _, rule := range rules(ipn) {
log.Info("Adding iptables rule: ", strings.Join(rule, " "))
err = ipt.AppendUnique("nat", "POSTROUTING", rule...)
if err != nil {
return fmt.Errorf("failed to insert IP masquerade rule: %v", err)
}
}
return nil
}