From 6d4a85a5ca8ed9ba47d55a06d75808bf508cd51e Mon Sep 17 00:00:00 2001
From: Boris Gallet <boris.gallet@gmail.com>
Date: Tue, 16 Apr 2024 16:55:49 +0200
Subject: [PATCH] [ADD] elab-monitor : init script handling disk and memory
 questions for restricted ssh connection

---
 README.md       |  22 +++++++++-
 elab-monitor.sh | 106 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 elab-monitor.sh

diff --git a/README.md b/README.md
index bdcb217..b5cfb0f 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,21 @@
-# this repo is a simple script to handle simple monitoring question on debian servers
+# Handle simple monitoring questions on debian servers via SSH
+
+## How to install 
+
+1. Clone the repo on the server 
+2. Force a system user to only used the elab-monitor.sh script 
+3. then you can `ssh $system_user@yourserver question`
+
+## Questions available 
+
+- disk_size
+- disk_available
+- disk_used
+- disk_used_percent
+- disk_available_percent
+
+- memory_size
+- memory_available
+- memory_used
+- memory_used_percent
+- memory_available_percent
\ No newline at end of file
diff --git a/elab-monitor.sh b/elab-monitor.sh
new file mode 100644
index 0000000..03caa4a
--- /dev/null
+++ b/elab-monitor.sh
@@ -0,0 +1,106 @@
+#!/bin/bash
+
+mkdir -p /var/log/monitoring
+
+LOG="/var/log/monitoring/elab-monitor.log"
+
+ssh_connection=(${SSH_CONNECTION})
+SSH_SOURCE_IP="${ssh_connection[0]}:${ssh_connection[1]}"
+
+log() {
+    printf "%s [%s] %s - %s\n" \
+           "$(date --rfc-3339=seconds)" "$$" "$SSH_SOURCE_IP" "$*" \
+           >> "$LOG"
+}
+
+log "NEW MONITORING CONNECTION"
+
+ident="$1"
+log "IDENTIFIED AS $ident"
+
+reject() {
+    log "REJECTED: $SSH_ORIGINAL_COMMAND"
+    # echo "ORIG: $SSH_ORIGINAL_COMMAND" >&2
+    echo "Your command has been rejected and reported to sys admin." >&2
+    exit 1
+}
+
+## TODO:  check how it’s made in the original script
+# sudo /usr/local/sbin/ssh-update-keys
+
+if [[ "$SSH_ORIGINAL_COMMAND" =~ [\&\(\{\;\<\>\`\$\}] ]]; then
+    log "BAD CHARS DETECTED"
+    # echo "Bad chars: $SSH_ORIGINAL_COMMAND" >&2
+    reject
+fi
+
+disk_size() {
+    val=$(df -h | awk '/\/$/ {print $2}')  # Retrieves the total disk size of the root filesystem
+    echo "$val"
+}
+
+disk_available() {
+    val=$(df -h | awk '/\/$/ {print $4}')  # Retrieves the available disk space of the root filesystem
+    echo "$val"
+}
+
+disk_used() {
+    val=$(df -h | awk '/\/$/ {print $3}')  # Retrieves the used disk space of the root filesystem
+    echo "$val"
+}
+
+disk_used_percent() {
+    val=$(df -h | awk '/\/$/ {print $5}')  # Retrieves the percentage of used disk space of the root filesystem
+    echo "$val"
+}
+
+disk_available_percent() {
+    val=$(df -h | awk '/\/$/ {print $4}')  # Retrieves the percentage of available disk space of the root filesystem
+    echo "$val"
+}
+
+memory_size() {
+    val=$(free -h | awk '/Mem:/ {print $2}')  # Retrieves the total memory size
+    echo "$val"
+}
+
+memory_available() {
+    val=$(free -h | awk '/Mem:/ {print $7}')  # Retrieves the available memory
+    echo "$val"
+}
+
+memory_used() {
+    val=$(free -h | awk '/Mem:/ {print $3}')  # Retrieves the used memory
+    echo "$val"
+}
+
+memory_used_percent() {
+    val=$(free | awk '/Mem:/ {printf "%.2f\n", (($2 - $7) / $2) * 100}')  # Calculates the percentage of used memory
+    echo "$val"
+}
+
+memory_available_percent() {
+    val=$(free | awk '/Mem:/ {printf "%.2f\n", ($7 / $2) * 100}')  # Calculates the percentage of available memory
+    echo "$val"
+}
+
+## ---- MAIN ----
+
+if [[ $SSH_ORIGINAL_COMMAND =~ ^[a-zA-Z0-9_]+$ ]]; then
+    log "ACCEPTED monitoring COMMAND : $SSH_ORIGINAL_COMMAND"
+    case "$SSH_ORIGINAL_COMMAND" in
+        disk_size) disk_size ;;
+        disk_available) disk_available ;;
+        disk_used) disk_used ;;
+        disk_used_percent) disk_used_percent ;;
+        disk_available_percent) disk_available_percent ;;
+        memory_size) memory_size ;;
+        memory_available) memory_available ;;
+        memory_used) memory_used ;;
+        memory_used_percent) memory_used_percent ;;
+        memory_available_percent) memory_available_percent ;;
+        *) reject ;;
+    esac
+else
+    reject
+fi
\ No newline at end of file