diff --git a/zerotier-network-hypervisor/src/util/testutil.rs b/zerotier-network-hypervisor/src/util/testutil.rs
new file mode 100644
index 000000000..15dafffdc
--- /dev/null
+++ b/zerotier-network-hypervisor/src/util/testutil.rs
@@ -0,0 +1,4 @@
+    // from zeronsd
+    pub fn randstring(len: u8) -> String {
+        (0..len).map(|_| (rand::random::<u8>() % 26) + 'a' as u8).map(|c| if rand::random::<bool>() { (c as char).to_ascii_uppercase() } else { c as char }).map(|c| c.to_string()).collect::<Vec<String>>().join("")
+    }