diff --git a/pkg/compute/models/guestnetworks.go b/pkg/compute/models/guestnetworks.go
index cc8892fca4..c18c0ee961 100644
--- a/pkg/compute/models/guestnetworks.go
+++ b/pkg/compute/models/guestnetworks.go
@@ -42,6 +42,9 @@ import (
 
 const (
 	MAX_IFNAME_SIZE = 13
+	MAX_HINT_LEN    = MAX_IFNAME_SIZE - 4          // 9
+	HINT_BASE_LEN   = 6                            // 6
+	HINT_RAND_LEN   = MAX_HINT_LEN - HINT_BASE_LEN // 3
 
 	MAX_GUESTNIC_TO_SAME_NETWORK = 2
 )
@@ -254,6 +257,23 @@ func (man *SGuestnetworkManager) ifnameUsed(ifname string) bool {
 	if ifname == "" {
 		return true
 	}
+	if len(ifname) > MAX_IFNAME_SIZE {
+		return true
+	}
+	isa := func(c byte) bool {
+		return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
+	}
+	if !isa(ifname[0]) {
+		return true
+	}
+	for i := range ifname[1:] {
+		c := ifname[i]
+		if isa(c) || c >= '0' || c <= '9' || c == '_' || c == '-' {
+			continue
+		}
+		return true
+	}
+
 	count, err := GuestnetworkManager.Query().Equals("ifname", ifname).CountWithError()
 	if err != nil {
 		panic(errors.Wrap(err, "query if ifname is used"))
diff --git a/pkg/compute/models/networks.go b/pkg/compute/models/networks.go
index 341154820b..d3b0a51339 100644
--- a/pkg/compute/models/networks.go
+++ b/pkg/compute/models/networks.go
@@ -1172,19 +1172,22 @@ func (manager *SNetworkManager) newIfnameHint(hint string) (string, error) {
 	}
 	sani := func(r string) string {
 		if r != "" && !isa(r[0]) {
-			return "a" + r
+			r = "a" + r
+		}
+		if len(r) > MAX_HINT_LEN {
+			r = r[:MAX_HINT_LEN]
 		}
 		return r
 	}
-	newHint := func(base string) (string, error) {
-		if len(base) > 8 {
-			base = base[:8]
+	rand := func(base string) (string, error) {
+		if len(base) > HINT_BASE_LEN {
+			base = base[:HINT_BASE_LEN]
 		}
 		for i := 0; i < 3; i++ {
-			r := base + rand.String(7)
+			r := sani(base + rand.String(HINT_RAND_LEN))
 			cnt, err := manager.Query().Equals("ifname_hint", r).CountWithError()
 			if err == nil && cnt == 0 {
-				return sani(r), nil
+				return r, nil
 			}
 		}
 		return "", fmt.Errorf("failed finding ifname hint after 3 tries")
@@ -1200,13 +1203,12 @@ func (manager *SNetworkManager) newIfnameHint(hint string) (string, error) {
 	r = sani(r)
 
 	if len(r) < 3 {
-		return newHint(r)
+		return rand(r)
 	}
 	if cnt, err := manager.Query().Equals("ifname_hint", r).CountWithError(); err != nil {
 		return "", err
 	} else if cnt > 0 {
-		r, err := newHint(r)
-		return r, err
+		return rand(r)
 	}
 	return r, nil
 }