diff --git a/check_iperf3.sh b/check_iperf3.sh
new file mode 100755
index 0000000..e96df58
--- /dev/null
+++ b/check_iperf3.sh
@@ -0,0 +1,96 @@
+#!/bin/bash
+
+function print_help {
+  echo "Usage: $0 --server SERVER --warning WARNING --critical CRITICAL --rsa-key RSA_KEY --username USERNAME --password PASSWORD"
+  echo ""
+  echo "Arguments:"
+  echo "  --server   The iperf3 server to test against"
+  echo "  --warning  Warning level for the speed test in Mbits/s"
+  echo "  --critical Critical level for the speed test in Mbits/s"
+  echo "  --rsa-key  Path to the RSA public key for authentication"
+  echo "  --username Username for authentication"
+  echo "  --password Password for authentication"
+  echo ""
+  exit 3
+}
+
+if ! command -v iperf3 &>/dev/null; then
+  echo "UNKNOWN - iperf3 is not installed"
+  exit 3
+fi
+
+if [[ $# -eq 0 ]]; then
+  print_help
+fi
+
+while [[ $# -gt 0 ]]; do
+  key="$1"
+
+  case $key in
+  --server)
+    SERVER="$2"
+    shift
+    shift
+    ;;
+  --warning)
+    WARNING="$2"
+    shift
+    shift
+    ;;
+  --critical)
+    CRITICAL="$2"
+    shift
+    shift
+    ;;
+  --rsa-key)
+    RSA_KEY="$2"
+    shift
+    shift
+    ;;
+  --username)
+    USERNAME="$2"
+    shift
+    shift
+    ;;
+  --password)
+    PASSWORD="$2"
+    shift
+    shift
+    ;;
+  *)
+    print_help
+    ;;
+  esac
+done
+
+if [[ -z "$SERVER" ]] || [[ -z "$WARNING" ]] || [[ -z "$CRITICAL" ]] || [[ -z "$RSA_KEY" ]] || [[ -z "$USERNAME" ]] || [[ -z "$PASSWORD" ]]; then
+  echo "UNKNOWN - All arguments are required"
+  print_help
+fi
+
+export IPERF3_PASSWORD="$PASSWORD"
+
+RESULT=$(iperf3 -c $SERVER -u -b 0 -J -t 10 --rsa-public-key-path $RSA_KEY --username $USERNAME 2>&1)
+if [[ $? -ne 0 ]]; then
+  echo "UNKNOWN - iperf3 command failed: $RESULT"
+  exit 3
+fi
+
+if ! echo "$RESULT" | jq -e '.end.sum.bits_per_second' >/dev/null; then
+  echo "UNKNOWN - Invalid JSON output from iperf3: $RESULT"
+  exit 3
+fi
+
+SPEED_RAW=$(echo "$RESULT" | jq '.end.sum.bits_per_second / 1000000')
+SPEED=$(printf "%.0f" "$SPEED_RAW")
+
+if (($(echo "$SPEED < $CRITICAL" | bc -l))); then
+  echo "CRITICAL - Speed: ${SPEED} Mbits/s"
+  exit 2
+elif (($(echo "$SPEED < $WARNING" | bc -l))); then
+  echo "WARNING - Speed: ${SPEED} Mbits/s"
+  exit 1
+else
+  echo "OK - Speed: ${SPEED} Mbits/s"
+  exit 0
+fi