Role LB - OCSP stapling

Recently, more use has been made of so-called OCSP stapling instead of CRL (Certificate Revocation Lists).

If OCSP stapling should be activated in haproxy, the following procedure is used.

See also this website: https://icicimov.github.io/blog/server/HAProxy-OCSP-stapling/ for a very good manual and explanation on which our manual here is based.

check haproxy.cfg

Check that the stats socket is activated. If a different socket is specified, the script must be adjusted below (two lines before exit 0 - in the socat command).

haproxy.cfg

global
        stats socket  /var/lib/haproxy/stats
        stats timeout 30s

install socat

Install socat

yum -y install socat

Create script for OCSP stapling and make it executable

Skript für OCSP stapling

cat <<EOFF > /usr/local/bin/haproxy_ocsp_update.sh
#!/bin/bash

# Certificates path and names
DIR="/etc/haproxy"
CERT="haproxy.pem"

# Get the issuer URI, download it's certificate and convert into PEM format
ISSUER_URI=\$(openssl x509 -in \${DIR}/\${CERT} -text -noout | grep 'CA Issuers' | cut -d: -f2,3)
ISSUER_NAME=\$(echo \${ISSUER_URI##*/} | while read -r fname; do echo \${fname%.*}; done)
wget -q -O- \$ISSUER_URI | openssl x509 -inform DER -outform PEM -out \${DIR}/\${ISSUER_NAME}.pem

# Get the OCSP URL from the certificate
ocsp_url=\$(openssl x509 -noout -ocsp_uri -in \${DIR}/\${CERT})

# Extract the hostname from the OCSP URL
ocsp_host=\$(echo \$ocsp_url | cut -d/ -f3)

# Create/update the ocsp response file and update HAProxy
openssl ocsp -noverify -no_nonce -issuer \${DIR}/\${ISSUER_NAME}.pem -cert \${DIR}/\${CERT} -url \$ocsp_url -header Host \$ocsp_host -respout \${DIR}/\${CERT}.ocsp
[[ \$? -eq 0 ]] && [[ \$(pidof haproxy) ]] && [[ -s \${DIR}/\${CERT}.ocsp ]] && echo "set ssl ocsp-response \$(/usr/bin/base64 -w 10000 \${DIR}/\${CERT}.ocsp)" | socat stdio unix-connect:/var/lib/haproxy/stats

exit 0
EOFF

chmod +x /usr/local/bin/haproxy_ocsp_update.sh

Test the script

Run the script with: /usr/local/bin/haproxy_ocsp_update.sh

Example return:

/etc/haproxy/haproxy.pem: good
This Update: Mar 25 15:33:54 2019 GMT
Next Update: Mar 28 15:33:54 2019 GMT

Activate CRON job for script

This will execute the script every day.