add get_public_ip method to sliver object
diff --git a/xos/core/models/sliver.py b/xos/core/models/sliver.py
index 1a421b0..0e74b1d 100644
--- a/xos/core/models/sliver.py
+++ b/xos/core/models/sliver.py
@@ -138,6 +138,12 @@
         return ", ".join(result)
     all_ips_string.short_description = "addresses"
 
+    def get_public_ip(self, sliver):
+        for ns in self.networkslivers.all():
+            if (ns.ip) and (ns.network.template.visibility=="public") and (ns.network.template.translation=="none"):
+                return ns.ip
+        return None
+
     @staticmethod
     def select_by_user(user):
         if user.is_admin: