Feat linux firewall support (#805)

Update the client's engine to apply firewall rules received from the manager (results of ACL policy).

client/internal/acl/manager_create_linux.go

@@ -0,0 +1,36 @@
+package acl
+
+import (
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/firewall"
+	"github.com/netbirdio/netbird/client/firewall/iptables"
+	"github.com/netbirdio/netbird/client/firewall/nftables"
+	"github.com/netbirdio/netbird/client/firewall/uspfilter"
+)
+
+// Create creates a firewall manager instance for the Linux
+func Create(iface iFaceMapper) (manager *DefaultManager, err error) {
+	var fm firewall.Manager
+	if iface.IsUserspaceBind() {
+		// use userspace packet filtering firewall
+		if fm, err = uspfilter.Create(iface); err != nil {
+			log.Debugf("failed to create userspace filtering firewall: %s", err)
+			return nil, err
+		}
+	} else {
+		if fm, err = iptables.Create(iface.Name()); err != nil {
+			log.Debugf("failed to create iptables manager: %s", err)
+			// fallback to nftables
+			if fm, err = nftables.Create(iface.Name()); err != nil {
+				log.Errorf("failed to create nftables manager: %s", err)
+				return nil, err
+			}
+		}
+	}
+
+	return &DefaultManager{
+		manager:    fm,
+		rulesPairs: make(map[string][]firewall.Rule),
+	}, nil
+}