diff --git a/service/src/main/java/com/github/kr328/clash/service/TunService.kt b/service/src/main/java/com/github/kr328/clash/service/TunService.kt
index f027190..453d830 100644
--- a/service/src/main/java/com/github/kr328/clash/service/TunService.kt
+++ b/service/src/main/java/com/github/kr328/clash/service/TunService.kt
@@ -13,9 +13,13 @@ import kotlinx.coroutines.launch
 
 class TunService : VpnService(), CoroutineScope by MainScope() {
     companion object {
-        private const val TUN_MTU = 9000
-        private const val TUN_DNS = "198.18.0.1"
-        private const val IPV4_ANY = "0.0.0.0/0"
+        // from https://github.com/shadowsocks/shadowsocks-android/blob/master/core/src/main/java/com/github/shadowsocks/bg/VpnService.kt
+        private const val VPN_MTU = 9000
+        private const val PRIVATE_VLAN4_SUBNET = 30
+        private const val PRIVATE_VLAN4_CLIENT = "172.31.255.253"
+        private const val PRIVATE_VLAN4_MIRROR = "172.31.255.254"
+        private const val PRIVATE_VLAN_DNS = "198.18.0.1"
+        private const val VLAN_ANY = "0.0.0.0/0"
     }
 
     private val service = this
@@ -104,27 +108,23 @@ class TunService : VpnService(), CoroutineScope by MainScope() {
     }
 
     private inner class TunConfigure(private val settings: ServiceSettings) : TunModule.Configure {
-        private val network = generateTunNetwork()
-
         override val builder: Builder
             get() = Builder()
         override val mtu: Int
-            get() = TUN_MTU
-        override val gateway: String = network.copyOf().apply {
-                this[3] = (this[3] + 1).toByte()
-            }.asAddressString("/30")
-        override val mirror: String = network.copyOf().apply {
-                this[3] = (this[3] + 2).toByte()
-            }.asAddressString()
+            get() = VPN_MTU
+        override val gateway: String
+            get() = "$PRIVATE_VLAN4_CLIENT/$PRIVATE_VLAN4_SUBNET"
+        override val mirror: String
+            get() = PRIVATE_VLAN4_MIRROR
         override val route: List<String>
             get() {
                 return if (settings.get(ServiceSettings.BYPASS_PRIVATE_NETWORK))
                     resources.getStringArray(R.array.bypass_private_route).toList()
                 else
-                    listOf(IPV4_ANY)
+                    listOf(VLAN_ANY)
             }
         override val dnsAddress: String
-            get() = TUN_DNS
+            get() = PRIVATE_VLAN_DNS
         override val dnsHijacking: Boolean
             get() = settings.get(ServiceSettings.DNS_HIJACKING)
         override val allowApplications: Collection<String>
@@ -143,29 +143,6 @@ class TunService : VpnService(), CoroutineScope by MainScope() {
         override fun onCreateTunFailure() {
             stopSelfForReason("Establish VPN rejected by system")
         }
-
-        private fun generateTunNetwork(): ByteArray {
-            val result = ByteArray(4)
-
-            // 18 bit namespace
-            val offset = UserUtils.currentUserId % 0x40000
-            val network = (0x3FFFF - offset) shl 2
-
-            result[0] = (172 or (network shr 24) and 0xFF).toByte()
-            result[1] = (16 or (network shr 16) and 0xFF).toByte()
-            result[2] = (0 or (network shr 8) and 0xFF).toByte()
-            result[3] = (0 or (network shr 0) and 0xFF).toByte()
-
-            return result
-        }
-
-        private fun ByteArray.asAddressString(suffix: String = ""): String {
-            return "${this[0].toUnsignedString()}.${this[1].toUnsignedString()}.${this[2].toUnsignedString()}.${this[3].toUnsignedString()}$suffix"
-        }
-
-        private fun Byte.toUnsignedString(): String {
-            return (this.toInt() and 0xFF).toString()
-        }
     }
 
     private fun stopSelfForReason(reason: String?) {
diff --git a/service/src/main/java/com/github/kr328/clash/service/util/UserUtils.kt b/service/src/main/java/com/github/kr328/clash/service/util/UserUtils.kt
deleted file mode 100644
index 8d2a0e9..0000000
--- a/service/src/main/java/com/github/kr328/clash/service/util/UserUtils.kt
+++ /dev/null
@@ -1,10 +0,0 @@
-package com.github.kr328.clash.service.util
-
-import android.os.Process
-
-object UserUtils {
-    private const val PER_USER_RANGE: Int = 100000
-
-    val currentUserId: Int
-        get() = Process.myUid() / PER_USER_RANGE
-}
\ No newline at end of file