Certificate

Security Certificate

1. Abstract: Create Certificate

   Generate key

   Generate signing request

   Sign the key

   Create server certificate

   Set permission

   Set owner

   Copy into place

   Restart services

   Implementation

   1. Self-Signed Certificate

      # openssl genrsa -out x.key 2048

      # openssl req -new -key x.key -out x.csr

      # openssl x509 -req -days 3650 -in x.csr -signkey x.key -out x.crt

      # cat x.crt x.key > servercert.pem

      # chmod 644 servercert.pem

      # chown root:qmail servercert.pem

      # cp -p servercert.pem /var/qmail/control

   2. Let's Encrypt (Assumes working web server)

      # yum install python-certbot-apache

      # certbot -apache -d mydomain.com -d mail.mydomain.com

      Apache

      SSLCertificateFile /etc/letsencrypt/live/mydomain.com/cert.pem

      SSLCertificateKeyFile /etc/letsencrypt/live/mydomain.com/privkey.pem

      SSLCertificateChainFile /etc/letsencrypt/live/mydomain.com/fullchain.pem

      Dovecot

      ssl_cert = </etc/letsencrypt/live/mydomain.com/fullchain.pem

      ssl_key = </etc/letsencrypt/live/mydomain.com/privkey.pem

      Qmail

      # cp -p /var/qmail/control/servercert.pem /var/qmail/control/servercert.pem.bak

      EL 7/8

      # cat /etc/letsencrypt/live/mydomain.com/privkey.pem /etc/letsencrypt/live/mydomain.com/fullchain.pem > /var/qmail/control/servercert.pem

      EL 9

      # cat /etc/letsencrypt/live/mydomain.com/fullchain.pem /etc/letsencrypt/live/mydomain.com/privkey.pem > /var/qmail/control/servercert.pem

      Cron auto renew (script below)

      0 0 * * * /opt/certbot/certbot renew

   3. Application: Godaddy Signed Certificate

      # openssl genrsa -out x.key 2048

      # openssl req -new -key x.key -out x.csr

      Submit signing request (x.csr) to Godaddy; Later download signed key (crt and crt bundle)

      # cat x.key 7531fdb8504afe19.crt gd_bundle-g2-g1.crt > servercert.pem

      # chmod 644 servercert.pem

      # chown root:qmail servercert.pem

      # cp -p servercert.pem /var/qmail/control

2. Restart Qmail and Dovecot

   # qmailctl stop && sleep 2 && qmailctl start

   # systemctl restart dovecot

   # systemctl restart httpd

#!/bin/bash

LOG=/usr/command/certs/certs.log
days=3

today=`date`
today=`date --date="$today" --utc +%s`
CD=/etc/letsencrypt/live
FC=fullchain.pem
PK=privkey.pem

mailcert () {
   if [[ "`cat /etc/os-release | grep VERSION_ID | sed 's/VERSION_ID=//' | sed 's/"//g'`" == *"9"* ]]
   then
      cat $CD/$1/$FC $CD/$1/$PK > ./servercert.pem
   else
      cat $CD/$1/$PK $CD/$1/$FC > ./servercert.pem
   fi
   cp -p /var/qmail/control/servercert.pem /var/qmail/control/servercert.pem.bak
   cp ./servercert.pem  /var/qmail/control/servercert.pem
   systemctl reload dovecot  
   qmailctl stop && sleep 2 && qmailctl start
}

for CDOM in `ls $CD`
do
   [ "$CDOM" = "README" ] && continue
   exp=`openssl x509 -dates -noout < $CD/$CDOM/$FC | grep notAfter | sed 's/notAfter=//'`
   off=`date --date="$exp" --utc +%s`
   diff=$(( (off - today)/86400 ))
   echo "Certificate Domain: $CDOM, Days to expire: $diff"
   echo ""
   if [ $diff -le $days ]
   then
      certbot renew --cert-name $CDOM
      systemctl reload httpd
      mailcert $CDOM
   fi
done

exit 0

Implementation (qmail run scripts)

Submission

#!/bin/sh
QMAILDUID=`id -u vpopmail`
NOFILESGID=`id -g vpopmail`
MAXSMTPD=`cat /var/qmail/control/concurrencyincoming`
SMTPD="/var/qmail/bin/qmail-smtpd"
TCP_CDB="/etc/tcprules.d/tcp.smtp.cdb"
HOSTNAME=`hostname`
VCHKPW="/home/vpopmail/bin/vchkpw"
export SMTPAUTH="!"

exec /usr/bin/softlimit -m 128000000 \
    /usr/bin/tcpserver -v -R -H -l $HOSTNAME -x $TCP_CDB -c "$MAXSMTPD" \
    -u "$QMAILDUID" -g "$NOFILESGID" 0 587 \
    $SMTPD $VCHKPW /bin/true 2>&1

SMTPS

#!/bin/sh
QMAILDUID=`id -u vpopmail`
NOFILESGID=`id -g vpopmail`
MAXSMTPD=`cat /var/qmail/control/concurrencyincoming`
SMTPD="/var/qmail/bin/qmail-smtpd"
TCP_CDB="/etc/tcprules.d/tcp.smtp.cdb"
HOSTNAME=`hostname`
VCHKPW="/home/vpopmail/bin/vchkpw"
export SMTPS=1
export FORCETLS=0
export SMTPAUTH="!+cram"

exec /usr/bin/softlimit -m 128000000 \
    /usr/bin/tcpserver -v -R -H -l $HOSTNAME -x $TCP_CDB -c "$MAXSMTPD" \
    -u "$QMAILDUID" -g "$NOFILESGID" 0 465 \
    $SMTPD $VCHKPW /bin/true 2>&1