On 11 Jan 2025, Warpslide said the following...

 Wa> I opted for proftpd as well and use its "virtual user" functionality.

[...]

 Wa> I still need to find a way to create a semaphore file when someone logs
 Wa> out of proftd.  There is an "ExecOnExit" but these are limited to the
 Wa> user's chrooted path.

In case someone else finds this useful, I asked ChatCPT to help me with a script
to run some commands when specified users log out of the proftpd server. It
seems to work well enough but hasn't been battle tested as of yet:


[-- begin monitor_ftp_log.sh --]
#!/bin/bash

# Path to the log file
LOG_FILE="/var/log/proftpd/proftpd.log"

# Declare an associative array to store user login info (PID -> User)
declare -A user_sessions

# List of specific users to monitor
MONITORED_USERS=("node23" "node99"

# Action to be performed when the session is closed
perform_action() {
  local user="$1"
  case "$user" in
    "node23" inbox="/home/ubuntu/fido/filebox/micronet_z618n400n23p1/in" ;;
    "node99" inbox="/home/ubuntu/fido/filebox/micronet_z618n400n99/in" ;;
  esac
  [ ! -z "$(ls "${inbox}"" ] && mv -n ${inbox}/*.* /home/ubuntu/fido/inbound &&
/home/ubuntu/fido/mailin.sh
}

# Function to check if a user is in the monitored list
is_monitored_user() {
  local user="$1"
  for monitored_user in "${MONITORED_USERS[@]}"; do
    if [[ "$user" == "$monitored_user" ]]; then
      return 0  # User is in the list
    fi
  done
  return 1  # User is not in the list
}

# Monitor the log file
tail -F "$LOG_FILE" | while read -r line; do

  # Check for successful login lines (USER <username>: Login successful)
  if [[ "$line" =~ USER\ ([a-zA-Z0-9]+):\ Login\ successful\. ]]; then
    user="${BASH_REMATCH[1]}"  # Extract the username

    # Extract PID from the first set of square brackets []
    pid=$(echo "$line" | awk -F'[][]' '{print $2}'

    # Only monitor specific users
    if is_monitored_user "$user"; then
      # Store the user and PID in the associative array
      user_sessions["$pid"]="$user"
    fi
  fi

  # Check for FTP session closed (FTP session closed with PID in the first set
of [])
  if [[ "$line" =~ \[([0-9]+)\].*FTP\ session\ closed\. ]]; then
    pid="${BASH_REMATCH[1]}"  # Extract the process ID (PID)

    # Check if this PID exists in the user_sessions array
    if [[ -n "${user_sessions[$pid]}" ]]; then
      user="${user_sessions[$pid]}"

      # Only perform action for monitored users
      if is_monitored_user "$user"; then
        perform_action "$user"  # Perform action for the associated user
      fi
      unset user_sessions["$pid"]  # Remove the entry after the action
    fi
  fi
done
[-- end monitor_ftp_log.sh --]


You can also find a copy at:
https://nrbbs.net/monitor_ftp_log.sh.txt


Jay

... What if soy milk is just regular milk introducing itself in spanish?

--- Mystic BBS v1.12 A49 2024/05/29 (Linux/64)
 * Origin: Northern Realms (618:400/23)