a few hours of work
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366
validate-my-dns.py
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366
validate-my-dns.py
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#!/usr/bin/env python3
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import hashlib
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import base64
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import struct
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import sys
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import os
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import subprocess
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import json
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REGISTRY_PATH = "../registry"
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# step1:
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def get_domain_by_mntner(mntner):
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"""get a list of domains (and reverse ipv4/6) if a nserver is specified"""
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# grep for the given mntner in the dns,inetnum,inet6num directory of the registry and split it into a list; replace // with / in case REGISTRY_PATH ends with /
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dns_files = subprocess.Popen(["grep", "-Ril", f" {mntner}", f"{REGISTRY_PATH}/data/dns/"],
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stdout=subprocess.PIPE).communicate()[0].decode().replace("//", "/").split("\n")[:-1]
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inetnums_files = subprocess.Popen(["grep", "-Ril", f" {mntner}", f"{REGISTRY_PATH}/data/inetnum/"],
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stdout=subprocess.PIPE).communicate()[0].decode().replace("//", "/").split("\n")[:-1]
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inet6nums_files = subprocess.Popen(
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["grep", "-Ril", f" {mntner}", f"{REGISTRY_PATH}/data/inet6num/"], stdout=subprocess.PIPE).communicate()[0].decode().split("\n")[:-1]
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# domains dict containing dns objects and inet(6)nums if they have nserver specified
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domains = {}
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# read dns files
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for domain in dns_files:
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with open(domain) as d:
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domain_name = domain.split("/")[-1]
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# a dictionary for each domain with "nserver": {"ns1.domain.dn42": ["ns1 ipv4", "ns1 ipv6"], ...}, "ds-rdata": ["123 45 67 ...", "98 7 65 ..."]
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domains[domain_name] = {"nserver": {}, "ds-rdata": []}
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for line in d.readlines():
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line = line.replace("\n", "")
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if line.startswith("nserver"):
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nserver = line[20:].split(" ")
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# handle edge case where
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if "\t" in nserver[0]:
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nserver = nserver[0].split("\t")
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# ignore registry-sync nservers
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if "registry-sync.dn42" in nserver[0]:
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break
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# nserver should be defined in an other dns file
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if len(nserver) == 1:
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domains[domain_name]["nserver"][nserver[0]] = None
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# nserver is defined in this file
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elif len(nserver) == 2:
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if nserver[0] not in domains[domain_name]["nserver"]:
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domains[domain_name]["nserver"][nserver[0]] = [nserver[1]]
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else:
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domains[domain_name]["nserver"][nserver[0]].append(nserver[1])
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elif line.startswith("ds-rdata:"):
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domains[domain_name]["ds-rdata"].append(line[20:])
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# load inetnums
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for inetnum in inetnums_files:
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# temp variables in case there is no nserver
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_nserver = {}
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_ds_rdata = []
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_domain_name = ""
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with open(inetnum) as i4:
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for line in i4.readlines():
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line = line.replace("\n", "")
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if line.startswith("cidr"):
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line = line[20:]
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_domain_name = ".".join(line.split(".")[::-1]) + ".in-addr.arpa"
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elif line.startswith("nserver"):
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nserver = line[20:].split(" ")
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# handle edge case where
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if "\t" in nserver[0]:
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nserver = nserver[0].split("\t")
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# ignore registry-sync nservers
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if "registry-sync.dn42" in nserver[0]:
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break
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# nserver should be defined in an other dns file
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if len(nserver) == 1:
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_nserver[nserver[0]] = None
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# nserver is defined in this file
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elif len(nserver) == 2:
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if nserver[0] not in _nserver:
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_nserver[nserver[0]] = [nserver[1]]
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else:
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_nserver[nserver[0]].append(nserver[1])
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elif line.startswith("ds-rdata:"):
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_ds_rdata.append(line[20:])
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# if nserver list is not empty add the reverse to the domain list
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if not _nserver == {}:
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domains[_domain_name] = {"nserver": _nserver, "ds-rdata":_ds_rdata}
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# load inet6nums
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for inet6num in inet6nums_files:
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# temp variables in case there is no nserver
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_nserver = {}
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_ds_rdata = []
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_domain_name = ""
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with open(inet6num) as i6:
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for line in i6.readlines():
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line = line.replace("\n", "")
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if line.startswith("inet6num"):
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line = line[20:]
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# generate the reverse ipv6
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_domain_name = "ip6.arpa"
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_lowest, _highest = line.replace(":","").split(" - ")
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for _digit1, _digit2 in zip(_lowest,_highest):
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if _digit1 != _digit2:
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break
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_domain_name = _digit1 + "." + _domain_name
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elif line.startswith("nserver"):
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nserver = line[20:].split(" ")
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# handle edge case where
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if "\t" in nserver[0]:
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nserver = nserver[0].split("\t")
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# ignore registry-sync nservers
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if "registry-sync.dn42" in nserver[0]:
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break
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# nserver should be defined in an other dns file
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if len(nserver) == 1:
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_nserver[nserver[0]] = None
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# nserver is defined in this file
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elif len(nserver) == 2:
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if nserver[0] not in _nserver:
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_nserver[nserver[0]] = [nserver[1]]
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else:
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_nserver[nserver[0]].append(nserver[1])
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elif line.startswith("ds-rdata:"):
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_ds_rdata.append(line[20:])
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# if nserver list is not empty add the reverse to the domain list
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if not _nserver == {}:
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domains[_domain_name] = {"nserver": _nserver, "ds-rdata":_ds_rdata}
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# add entries from main domain, if the nserver doesn't have an ip address (like in inet(6)nums)
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for domain in domains:
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for nserver in domains[domain]["nserver"]:
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# if the nserver isn't specified: ...
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if domains[domain]["nserver"][nserver] == None:
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#print(f"INFO: the nserver {nserver} isn't specified in {domain}, looking into the parent domain of it")
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for i in range(len(nserver.split(".")), 1, -1):
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# check if the nserver is already in loaded database, starts with more specific
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if ".".join(nserver.split(".")[-i:]) in domains:
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try:
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domains[domain]["nserver"][nserver] = domains[".".join(nserver.split(".")[-i:])]["nserver"][nserver]
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except KeyError:
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# reaches here if the domain for the nserver specified in the inet{6}num/domain is found, but the nserver itself not.
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print(f"Warn: the nserver {nserver} specified in {domain} wasn't found")
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break
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return domains
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def get_dnskey(domain, nserver=None):
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"""query dns server for DNSKEY"""
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if not nserver:
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# drill: use DNSSEC, fallback to tcp, for $domain
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drill_cmd = subprocess.Popen(
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["drill", "-D", "-a", "DNSKEY", domain], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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else:
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# drill: use DNSSEC, fallback to tcp, ask $nserver for $domain
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drill_cmd = subprocess.Popen(
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["drill", "-D", "-a", "DNSKEY", f"@{nserver}", domain], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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# get the output of the drill command
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lines = drill_cmd.communicate()[0].decode().split("\n")
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# filter out comments (;;) and empty lines
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new_lines = []
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for line in lines:
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if line == "" or line.startswith(";;"):
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continue
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new_lines.append(line)
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lines = new_lines
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# split records into domain and key
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dnskeys = [[record.split("\t")[0], record.split("\t")[-1]]
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for record in lines]
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#print(len(dnskeys))
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return dnskeys
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# end_step1
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# step 2: <start dnskey_to_DS.py based on https://gist.github.com/wido/4c6288b2f5ba6d16fce37dca3fc2cb4a >
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"""
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Generate a DNSSEC DS record based on the incoming DNSKEY record
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The DNSKEY can be found using for example 'dig':
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$ dig DNSKEY secure.widodh.nl
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The output can then be parsed with the following code to generate a DS record
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for in the parent DNS zone
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Author: Wido den Hollander <wido@widodh.nl>
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Many thanks to this blogpost: https://www.v13.gr/blog/?p=239
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"""
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def _calc_keyid(flags, protocol, algorithm, dnskey):
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st = struct.pack('!HBB', int(flags), int(protocol), int(algorithm))
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st += base64.b64decode(dnskey)
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cnt = 0
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for idx in range(len(st)):
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s = struct.unpack('B', st[idx:idx+1])[0]
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if (idx % 2) == 0:
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cnt += s << 8
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else:
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cnt += s
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return ((cnt & 0xFFFF) + (cnt >> 16)) & 0xFFFF
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def _calc_ds(domain, flags, protocol, algorithm, dnskey):
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if domain.endswith('.') is False:
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domain += '.'
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signature = bytes()
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for i in domain.split('.'):
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signature += struct.pack('B', len(i)) + i.encode()
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signature += struct.pack('!HBB', int(flags), int(protocol), int(algorithm))
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signature += base64.b64decode(dnskey)
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return {
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'sha1': hashlib.sha1(signature).hexdigest().upper(),
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'sha256': hashlib.sha256(signature).hexdigest().upper(),
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}
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def dnskey_to_ds(domain, dnskey):
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dnskeylist = dnskey.split(' ', 3)
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flags = dnskeylist[0]
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protocol = dnskeylist[1]
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algorithm = dnskeylist[2]
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key = dnskeylist[3].replace(' ', '')
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keyid = _calc_keyid(flags, protocol, algorithm, key)
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ds = _calc_ds(domain, flags, protocol, algorithm, key)
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ret = list()
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ret.append(str(keyid) + ' ' + str(algorithm) + ' ' + str(1) + ' '
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+ ds['sha1'].lower())
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ret.append(str(keyid) + ' ' + str(algorithm) + ' ' + str(2) + ' '
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+ ds['sha256'].lower())
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return ret
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# if __name__ == "__main__":
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# print(len(sys.argv))
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# if len(sys.argv) == 1:
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# print("no data specified, please enter manually")
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# DOMAIN = input("enter domain: ")
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# DNSKEY = input("enter DNSKEY: ")
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#
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# print(dnskey_to_ds(DOMAIN, DNSKEY))
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# elif len(sys.argv) in [9,10]:
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# # user pasted full dig output
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# DOMAIN = sys.argv[1]
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# DNSKEY = " ".join(sys.argv[5:])
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# print(DOMAIN)
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# print(DNSKEY)
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# print(dnskey_to_ds(DOMAIN,DNSKEY))
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# step2: <end dnskey_to_DS.py>
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# step3: start: partially stolen from: https://stackoverflow.com/questions/26137036/programmatically-check-if-domains-are-dnssec-protected
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def check_dnssec(domain_name, domain_data):
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import dns.name
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import dns.query
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import dns.dnssec
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import dns.message
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import dns.resolver
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import dns.rdatatype
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import dns.exception
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success = False
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no_ds_rdata = domain_data["ds-rdata"] == []
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if no_ds_rdata:
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print(f"INFO: {domain_name} doesn't have ds-rdata configured, not checking it")
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for nserver in domain_data["nserver"]:
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# if the nserver is not set (i.e. not loaded from other dns file or "wrong" fqdn)
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if domain_data["nserver"][nserver] == None:
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print(f"INFO: ip address(es) for nserver '{nserver}' in '{domain_name}' isn't specified/loaded")
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continue
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for nsaddr in domain_data["nserver"][nserver]:
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# get SOA
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request = dns.message.make_query(domain_name, dns.rdatatype.SOA,want_dnssec=False)
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try:
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# send the query
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dns.query.udp(request,nsaddr, timeout=2)
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# if it timed out: tell the user
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except dns.exception.Timeout:
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print(f"WARN: querying {nserver} ({nsaddr}) for {domain_name} timed out")
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continue
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if no_ds_rdata:
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print(f"INFO: query for {domain_name} SOA on {nserver} ({nsaddr}) succeded, not checking DNSSEC")
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continue
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# get DNSKEY for zone
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request = dns.message.make_query(domain_name, dns.rdatatype.DNSKEY,want_dnssec=True)
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response = dns.query.udp(request,nsaddr, timeout=2)
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if response.rcode() != 0:
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# HANDLE QUERY FAILED (SERVER ERROR OR NO DNSKEY RECORD)
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print(f"WARN: query for a DNSKEY on {domain_name} failed on {nserver} ({nsaddr}), returncode: {response.rcode()}")
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continue
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# answer should contain two RRSET: DNSKEY and RRSIG(DNSKEY)
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answer = response.answer
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if len(answer) != 2:
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# SOMETHING WENT WRONG
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print(f"ERROR: query for a DNSKEY on {domain_name} failed on {nserver} ({nsaddr}), invalid answer length: {len(answer)}")
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continue
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# the DNSKEY should be self signed, validate it
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name = dns.name.from_text(domain_name)
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try:
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#print(f"DEBUG: answer[0]: {answer[0]}")
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#print(f"DEBUG: answer[1]: {answer[1]}")
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try:
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dns.dnssec.validate(answer[0],answer[1],{name:answer[0]})
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# it raises an AttributeError if the records are in the wrong order
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except AttributeError as e:
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dns.dnssec.validate(answer[1],answer[0],{name:answer[0]})
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except dns.dnssec.ValidationFailure:
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# BE SUSPICIOUS
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print(f"WARN: DNSSEC validation failed on {domain_name} failed on {nserver} ({nsaddr}), answer: {answer}")
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except AttributeError as e:
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print(f"ERROR: {e}")
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else:
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# WE'RE GOOD, THERE'S A VALID DNSSEC SELF-SIGNED KEY FOR example.com
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print(f"INFO: DNSSEC validation succeded on {domain_name} failed on {nserver} ({nsaddr})")
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success = True
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return success
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# step3: end
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def main(mntner):
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domains = get_domain_by_mntner(mntner=mntner)
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#with open("domains.tmp", "w") as domain_file:
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# json.dump(domains, domain_file, indent=4)
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# print(domains)
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for domain_name in domains:
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print(check_dnssec(domain_name, domains[domain_name]))
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if __name__ == "__main__":
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if len(sys.argv) == 1:
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print(f"please specify your mntner\n {sys.argv[0]} YOU-MNT")
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exit(1)
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main(sys.argv[1])
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# commands to run:
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# 1. drill -D <domain>.dn42 @ns1.<domain>.dn42 NS
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# 2. dnskey_to_ds("<domain>.dn42"
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# #<TTL> IN DNSKEY
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# "257 3 13 <base64 ...>")
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# 3. write dnskey to "trust-anchor"
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# 4.delv @ns1.<domain.dn42 +root=<domain>.dn42 -a ./trust-anchor.tmp SOA <domain>.dn42
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