diff --git a/nix/os/devices/CFB4ED74/system.nix b/nix/os/devices/CFB4ED74/system.nix
index 5da4f39..b2ff413 100644
--- a/nix/os/devices/CFB4ED74/system.nix
+++ b/nix/os/devices/CFB4ED74/system.nix
@@ -11,6 +11,10 @@ in {
   networking.hostName = "CFB4ED74"; # Define your hostname.
 
   networking.firewall.enable = true;
+  networking.firewall.allowedTCPPorts = [
+    # iperf3
+    5201
+  ];
   networking.interfaces.eth0 = {
     useDHCP = true;
     ipv6.addresses = [ {