PFX exporter for OPNsense's ACME plugin's certificates. A bash script.

The ACME client on OPNsense has a lot of useful utilities (such as installing certificates on Synology's DSM and automated push over SSH that though doable on other systems, each user admin has to come up with their own scheme. It's not perfect, as everything-else-OPNsense, it's poorly documented but it does the job nevertheless.

Certain servers require PFX certificates and will refuse other formats. PFX are bundle files, that usually include the whole chain of certificates (public keys) as well as the private key of the issued certificate. Since they have a private key, they also often have a password protecting them. You may skip this password but you will still have to press return/enter to accept it IF the recipient server tolerates it, most will not and they will refuse it outright.

The original idea for this was to add an automation per certificate so the process would focus only on that certificate, but there's no documentation about it (on OPNsense's documentation at least) so instead it works in bulk.

The ACME plugin creates a random directory under /var/etc/acme-client/certs where it puts the public keys and a matching directory on /var/etc/acme-client/keys where the private keys are stored. The randomness of this directory is in part why a targeted approach couldn't be made.

So instead the script will list the subdirectories of /var/etc/acme-client/certs to confirm there's a cert.pem and chaim.pem in it, then search for a private.key file the private keys subdirectory. If all files are found, then it will decode the common name of the certificate and use that name to name the new file with the extension .pfx which will be placed on /var/etc/acme-client/pfx which it will protect using the password stored in the file indicated in the variable pfile, by default this is: /var/etc/acme-client/pfiles/std

pfxexx

#!/usr/bin/env bash
 
printOPTIONS() {
  cat << _options
┌────────────────────────────────────────────────────────────────────────────i─┐
│ pfxexx — PFX Exporter for the ACME plugin on OPNsense                        │
│ Copyright (C) 2025  Gustavo Domínguez                                        │
│ GNU General Public License version 3                                         │
├─────────────────────────────────────────────────────────OPTIONS/REQUIREMENTS─┤
│ There are no real options*, only requirements:                               │
│ 1. The script requires bash to run. To install run: 'pkg install -y bash'.   │
│ 2. Variables must be reviewed or changed before running the script.          │
│    - Likely the most important will be the password file, the "pfile" from   │
│      which a password will be read in order to set it on PFX exports.        │
│                                                                              │
│ *: except for --unmute and --debug, neither of which affects how the script  │
│    works in terms of exporting PFXs. See more info at:                       │
│    https://ref.vitanetworks.link/en/utility-scripts/pfxexx                   │
├────────────────────────────────────────────────────────────────────────────@─┤
│ Gustavo Domínguez <deliver@senseivita.com>                                   │
│ senseivita.com | antipostal.com | vitanetworks.link                          │
└──────────────────────────────────────────────────────────────────────────────┘
_options
}
restoreOptions(){ set +e ; set +x ; set +v;}
enableDebugOptions(){ set -e ; set -x ; set -v;}
trap restoreOptions ERR EXIT
if [[ $1 =~ "debug" ]]; then enableDebugOptions; fi
 
verifiedPieces=''
cbn='/var/etc/acme-client/certs'
kbn='/var/etc/acme-client/keys'
ebn='/var/etc/acme-client/pfx'
cnlist=''
pfile='/var/etc/acme-client/pfiles/std'
 
main() {
 
  checkPfxExportDir() {
    if ! [[ -d "$ebn" ]]; then
      mkdir -p "$ebn"
    fi
  }
 
  candidates=( "$(find "$cbn" -type d -mindepth 1 -print0 | xargs -0 basename -s "$cbn")" )
  echo "${candidates[*]}"
 
  partsCheck() {
    for i in "${candidates[@]}"; do
      echo "$i"
      if [[ -f "$cbn/$i/cert.pem" ]]; then
        echo "$cbn/$i/cert.pem"
        if [[ -f "$cbn/$i/chain.pem" ]]; then
          echo "$cbn/$i/chain.pem"
          if [[ -f "$kbn/$i/private.key" ]]; then
            echo "$kbn/$i/private.key"
            verifiedPieces+=( "$i" )
          else continue; fi
        else continue; fi
      else continue; fi
    done
  }
 
  exportPFXs() {
    for iset in "${verifiedPieces[@]}"; do
      cn=$(openssl x509 -noout -subject -in "$cbn/$iset/cert.pem" | awk '{print $3}')
      cnlist+=( "$cn" )
      openssl pkcs12 -export -out "$ebn/$cn.pfx" -inkey "$kbn/$iset/private.key" -in "$cbn/$iset/cert.pem" -certfile "$cbn/$iset/chain.pem" -password file:"$pfile"
    done
  }
 
  printResuts() {
    echo Found the following certificates:
    printf '%s\n' "${cnlist[*]}"
  }
 
if checkPfxExportDir; then
  if partsCheck; then
    if exportPFXs; then
      echo "Finished successfully."
      printResuts
    else
      if [[ $1 =~ "debug" ]]; then echo "Failed exportPFXs"; fi
      exit
    fi
  else
    if [[ $1 =~ "debug" ]]; then echo "Failed partsCheck"; fi
    exit
  fi
else
  if [[ $1 =~ "debug" ]]; then echo "Failed checkPfxExportDir"; fi
  exit
fi
}
 
while [ "$1" != "" ]; do
  case "$1" in
    -h|--help|--options|help) printOPTIONS ;;
    --debug|debug) shift; main debug ;;
    --unmute) main ;;
    *) main > /dev/null 2>&1 ;;
  esac
  shift
done