diff --git a/src/bind.c b/src/bind.c
index c40ef0f..0bf6c41 100644
--- a/src/bind.c
+++ b/src/bind.c
@@ -310,7 +310,7 @@ gt_bind(int argc, char **argv)
             if (r <= 0) {
                 if (r == -1 && errno != EAGAIN)
                     perror("tun_read");
-            } else if ((!ip_get_common(&ic, buf, r)) && (ic.size == r) &&
+            } else if ((!ip_get_common(&ic, buf, r)) &&
                        (mud_send(mud, buf, r, ic.tc) == -1)) {
                 if (errno == EMSGSIZE) {
                     mtu = gt_setup_mtu(mud, tun_name);
@@ -327,7 +327,7 @@ gt_bind(int argc, char **argv)
             if (r <= 0) {
                 if (r == -1 && errno != EAGAIN)
                     perror("mud_recv");
-            } else if ((!ip_get_common(&ic, buf, r) && (ic.size == r)) &&
+            } else if ((!ip_get_common(&ic, buf, r)) &&
                        (tun_write(tun_fd, buf, r) == -1)) {
                 if (errno != EAGAIN)
                     perror("tun_write");
diff --git a/src/ip.h b/src/ip.h
index 28095a8..6d5273d 100644
--- a/src/ip.h
+++ b/src/ip.h
@@ -3,32 +3,10 @@
 #include <stdint.h>
 
 struct ip_common {
-    uint8_t version;
     uint8_t tc;
     uint8_t proto;
-    uint8_t hdr_size;
-    uint16_t size;
 };
 
-_pure_ static inline uint8_t
-ip_get_version(const uint8_t *data, size_t size)
-{
-    if (size < 20)
-        return 0;
-
-    return data[0] >> 4;
-}
-
-static inline uint32_t
-ip_read32(const uint8_t *src)
-{
-    uint32_t ret = src[3];
-    ret |= ((uint32_t)src[2]) << 8;
-    ret |= ((uint32_t)src[1]) << 16;
-    ret |= ((uint32_t)src[0]) << 24;
-    return ret;
-}
-
 static inline uint16_t
 ip_read16(const uint8_t *src)
 {
@@ -37,45 +15,22 @@ ip_read16(const uint8_t *src)
     return ret;
 }
 
-static inline size_t
-ip_get_mtu(struct ip_common *ic, const uint8_t *data, size_t size)
-{
-    if (ic->hdr_size <= 0 || ic->hdr_size + 8 > size)
-        return 0;
-
-    const uint8_t *p = &data[ic->hdr_size];
-
-    if (ic->version == 4 && ic->proto == 1 && p[0] == 3)
-        return ip_read16(&p[6]);
-
-    // not tested..
-    // if (ic->version == 6 && ic->proto == 58 && p[0] == 2)
-    //    return ip_read32(&p[4]);
-
-    return 0;
-}
-
 static inline int
 ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size)
 {
-    ic->version = ip_get_version(data, size);
+    if (size < 20)
+        return 1;
 
-    switch (ic->version) {
+    switch (data[0] >> 4) {
     case 4:
         ic->tc = data[1];
         ic->proto = data[9];
-        ic->hdr_size = (data[0] & 0xF) << 2;
-        ic->size = ip_read16(&data[2]);
-        if (ic->size >= 20)
-            return 0;
-        break;
+        return size != ip_read16(&data[2]);
     case 6:
         ic->tc = ((data[0] & 0xF) << 4) | (data[1] >> 4);
         ic->proto = data[6];
-        ic->hdr_size = 40;
-        ic->size = ip_read16(&data[4]) + 40;
-        return 0;
+        return size != ip_read16(&data[4]) + 40;
     }
 
-    return -1;
+    return 1;
 }