check_iperf3: update docs

check_iperf3.sh

@@ -1,5 +1,40 @@
 #!/usr/bin/env bash
 
+#
+# This script requires an iPerf3 server.
+#
+# How to set up the server:
+# 1. `sudo apt install iperf3`
+# 2. `mkdir -p /etc/iperf3`
+# 3. Set a username and password (password does not matter, we're going to use key-based authentication): `S_USER=your_username S_PASSWD=your_password`
+# 4. Hash your password: `echo -n "{$S_USER}$S_PASSWD" | sha256sum | awk '{ print $1 }'`
+# 5. Put the output in /etc/iperf3/users.csv like this:
+# mario,bf7a49a846d44b454a5d11e7acfaf13d138bbe0b7483aa3e050879700572709b
+# 6. Generate your server key: `openssl genrsa -des3 -out /etc/iperf3/iperf3_server.private.pem 2048`
+# 7. Generate your public key: `openssl rsa -in /etc/iperf3/iperf3_server.private.pem -outform PEM -pubout -out /etc/iperf3/iperf3.public.pem`
+# 8. Generate the key for iPerf3: `openssl rsa -in /etc/iperf3/iperf3_server.private.pem -out /etc/iperf3/iperf3_client.public.pem -outform PEM`
+# 9: Create the systemd service:
+# cat > /etc/systemd/system/iperf3.service <<EOF
+# [Unit]
+# Description=iperf3 server
+# After=syslog.target network.target auditd.service
+#
+# [Service]
+# ExecStart=/usr/bin/iperf3 -s --rsa-private-key-path /etc/iperf3/server.private.pem --authorized-users-path /etc/iperf3/users.csv
+#
+# [Install]
+# WantedBy=multi-user.target
+# EOF
+#
+# 10. systemctl daemon-reload
+# 11. systemctl enable --now iperf3
+# 12. systemctl status iperf3
+# 13. Run the client
+#
+
+# Warnng and critical levels are based on your specific network speed.
+
+
 # Default values
 SERVER=""
 WARNING_LEVEL=""
@@ -49,6 +84,11 @@ while [[ $# -gt 0 ]]; do
   esac
 done
 
+if ! command -v iperf3 &>/dev/null; then
+  echo "UNKNOWN - iperf3 not found! Please install iperf3"
+  exit -1
+fi
+
 # Check if required arguments are provided
 if [[ -z "$SERVER" ]] || [[ -z "$WARNING_LEVEL" ]] || [[ -z "$CRITICAL_LEVEL" ]]; then
   echo "Usage: $0 --server SERVER --warning WARNING_LEVEL --critical CRITICAL_LEVEL [--rsa-public-key RSA_PUBLIC_KEY] [--username USERNAME] [--password PASSWORD]"
@@ -67,7 +107,7 @@ fi
 
 # Check if iperf3 command failed
 if [[ $? -ne 0 ]]; then
-  echo "UNKNOWN - iperf3 command failed: $OUTPUT"
+  echo -e "UNKNOWN - iperf3 command failed: $OUTPUT\n"
   exit -1
 fi