record_ssh.sh

#!/bin/bash

if [[ -z $SSH_ORIGINAL_COMMAND ]]; then

  # The format of log files is /var/log/bastion/YYYY-MM-DD_HH-MM-SS_user
  LOG_FILE=$(date --date="today" "+%Y-%m-%d_%H-%M-%S"_$(whoami))
  LOG_DIR="/var/log/bastion/"

  # Print a welcome message
  echo ""
  echo "NOTE: This SSH session will be recorded"
  echo "AUDIT KEY: $LOG_FILE"
  echo ""

  # I suffix the log file name with a random string. I explain why 
  # later on.
  SUFFIX=$(mktemp -u _XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX)

  # Wrap an interactive shell into "script" to record the SSH session
  script -qf --timing=$LOG_DIR$LOG_FILE$SUFFIX.time $LOG_DIR$LOG_FILE$SUFFIX.data --command=/etc/profile.d/userlist.sh

else

  # The "script" program could be circumvented with some commands 
  # (e.g. bash, nc). Therefore, I intentionally prevent users 
  # from supplying commands.

  echo "This bastion supports interactive sessions only. Do not supply a command"
  exit 1

fi