Created
June 22, 2018 22:03
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Resolve all known ip addresses from spf record and generate cidr map for postfix
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#!/usr/bin/env python | |
# | |
# get_subnets_of_spf_record_mynetwoks.py | |
# Resolve all known ip addresses from spf record and generate cidr map for postfix | |
# | |
# Version 1.0 | |
# Written by Maximilian Thoma (http://www.lanbugs.de) | |
# | |
# Checkout blog article: | |
# https://lanbugs.de/howtos/linux/subnetze-und-ip-adressen-extrahieren-aus-spf-records-z-b-office365-oder-google-apps-for-business/ | |
# | |
# The generated files can be used in postfix config with for example mynetworks = cidr:/etc/postfix/<generated_file> | |
# | |
# This program is free software; you can redistribute it and/or modify it under the terms of the | |
# GNU General Public License as published by the Free Software Foundation; | |
# either version 2 of the License, or (at your option) any later version. | |
# | |
# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; | |
# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | |
# See the GNU General Public License for more details. | |
# | |
# You should have received a copy of the GNU General Public License along with this program; | |
# if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, | |
# MA 02110, USA | |
# | |
# | |
# Requirements: | |
# dnspython module -> pip install dnspython | |
# | |
import dns.resolver | |
from dns.exception import DNSException | |
import re | |
import sys | |
# Look for DNS Record at: | |
# | |
# "jobname": { | |
# "domain": "domainname", | |
# "file": "output_file", | |
# } | |
# | |
# | |
lookup_spf = { | |
# Google Apps for Business | |
"google": { | |
"domain": "google.com", | |
"file" : "/etc/postfix/networks/google", | |
}, | |
# Office365 | |
"office365": { | |
"domain": "spf.protection.outlook.com", | |
"file" : "/etc/postfix/networks/office365", | |
}, | |
} | |
############################################################################################ | |
def getspf(record, filehandler): | |
# Init Resolver | |
myResolver = dns.resolver.Resolver() | |
try: | |
# Try to lookup TXT record | |
myAnswer = myResolver.query(record,"TXT") | |
except DNSException: | |
sys.stderr.write("Failed to query record, SPF broken.") | |
return | |
results = [] | |
for rdata in myAnswer: | |
# Get string out of records | |
for txt_string in rdata.strings: | |
# Append to SPF Records buffer if "spf" in string | |
if "spf" in txt_string: | |
results.append(txt_string) | |
# If results >=1 | |
if len(results) >= 1: | |
# Work on records | |
for spf in results: | |
# Split parts | |
parts = spf.split(" ") | |
# Check parts | |
for part in parts: | |
s_include = re.match(r"^include:(?P<domain>.*)$", part) | |
s_ip4 = re.match(r"^ip4:(?P<ip4>.*)$", part) | |
s_ip6 = re.match(r"^ip6:(?P<ip6>.*)$", part) | |
# If in part "include" found, next round | |
if s_include: | |
getspf(s_include.group('domain'), filehandler) | |
# elif ip4 found | |
elif s_ip4: | |
filehandler.write(s_ip4.group('ip4') + " OK\n") | |
# elif ip6 found | |
elif s_ip6: | |
filehandler.write("[" + s_ip6.group('ip6').replace("/","]/") + " OK\n") | |
# else no valid record | |
else: | |
pass | |
# no results | |
else: | |
sys.stderr.write("No results") | |
pass | |
def main(): | |
# Working on jobs | |
for jobname, config in lookup_spf.iteritems(): | |
print "Working on job %s" % jobname | |
# open file | |
filehandler = open(config['file'], 'w') | |
# start query spf records | |
getspf(config['domain'], filehandler) | |
# close file | |
filehandler.close() | |
#getspf(lookup_spf) | |
if __name__ == "__main__": | |
main() |
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