diff --git a/docker-rsync/hosts-add b/docker-rsync/hosts-add
new file mode 100755
index 0000000..bd2c1df
--- /dev/null
+++ b/docker-rsync/hosts-add
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -euo pipefail
+
+echo "$@" >> ~/.ssh/known_hosts