Create opendkim configuration under Debian.

setup-opendkim.sh

#!/bin/bash
#
# to use with Postfix.
# Exim users, get out of here! Write your own scripts.
#
set -e

serviceIP="127.0.0.2"
servicePort=1051

keybits=1024    # godaddy has limited TXT record size

opendkim_conf=/etc/opendkim.conf
postfix_conf=/etc/postfix/main.cf


#
apt install -y opendkim opendkim-tools

#
domainname=$(domainname)
[ -f /etc/mailname ] && mailname=$(cat /etc/mailname)
echo -n "Enter your domain name or leave empty for '$domainname': "; read input
[ -n "$input" ] && domainname=$input
#
nodename=$(hostname)
echo -n "Enter your node name or leave empty for '$nodename': "; read input
[ -n "$input" ] && nodename=$input

#
#grep -q "^Socket" $opendkim_conf || \
grep -q "inet:$servicePort@$serviceIP" $opendkim_conf || \
echo "AutoRestart             Yes
AutoRestartRate         10/1h
UMask                   002
Syslog                  yes
SyslogSuccess           Yes
LogWhy                  Yes

Canonicalization        relaxed/simple

ExternalIgnoreList      refile:/etc/opendkim/TrustedHosts
InternalHosts           refile:/etc/opendkim/TrustedHosts
KeyTable                refile:/etc/opendkim/KeyTable
SigningTable            refile:/etc/opendkim/SigningTable

Mode                    sv
PidFile                 /var/run/opendkim/opendkim.pid
SignatureAlgorithm      rsa-sha256

UserID                  opendkim:opendkim

Socket                  inet:$servicePort@$serviceIP
" >> $opendkim_conf

#
for key in smtpd_milters non_smtpd_milters;do
        value="inet:$serviceIP:$servicePort"
        grep -q "^$key" $postfix_conf  && echo "add $value to $key in $postfix_conf!" || echo "$key = $value" >>$postfix_conf
done



#
[ -d /etc/opendkim/keys ] || mkdir -p /etc/opendkim/keys
cd /etc/opendkim

[ -f TrustedHosts ] || echo "127.0.0.1
localhost
#192.168.0.1/24
#*.example.net
#*.example.org
" >TrustedHosts


#
keydir=/etc/opendkim/keys/$domainname
[ -f KeyTable ] || echo "$nodename._domainkey.$domainname $domainname:$nodename:$keydir/$nodename.private" >KeyTable

[ -f SigningTable ] || echo "*@$domainname $nodename._domainkey.$domainname" >SigningTable

[ -d $keydir ] || mkdir -p $keydir

opendkim-genkey -b $keybits -s $nodename -d $domainname
chown opendkim:opendkim $nodename.private

service opendkim restart
service postfix restart

echo "add this to DNS:"
cat $nodename.txt