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#!/usr/bin/env python3
import argparse
import ipaddress
import netifaces
import logging
import logging.handlers
import os.path
import socket
import subprocess
import sys
def build_ip(ip_string):
try:
ip = ipaddress.ip_address(ip_string)
except ValueError:
log.error("manually specified address is invalid format: %s" % ip_string)
sys.exit(1)
except:
log.error(str(e))
sys.exit(1)
return ip
def get_interface_addrs(iface, addrtype):
try:
iaddrs = netifaces.ifaddresses(iface)
i = iaddrs[addrtype]
log.debug("interface {} addrs of type {}: {}".format(iface,addrtype,i))
except ValueError as e:
log.debug("Exception class: {}".format(e.__class__))
log.error("No interface named {} found".format(iface))
sys.exit(1)
except KeyError as e:
log.debug("Exception class: {}".format(e.__class__))
log.error("No address of type {} found on interface {}".format(addrtype, iface))
sys.exit(1)
except Exception as e:
log.debug("Exception class: {}".format(e.__class__))
log.error(str(e))
sys.exit(1)
return i
def build_nsupdate_cmd(server, zone, record, rrtype, ttl, addr):
log.debug("BNC: server: {}".format(server))
log.debug("BNC: zone: {}".format(zone))
log.debug("BNC: record: {}".format(record))
log.debug("BNC: rrtype: {}".format(rrtype))
log.debug("BNC: ttl: {}".format(ttl))
log.debug("BNC: addr: {}".format(addr))
cmdstr = "server {}\n".format(server)
cmdstr += "zone {}\n".format(zone)
cmdstr += "update delete {} {}\n".format(record, rrtype)
cmdstr += "update add {} {} {} {}\n".format(record, ttl, rrtype, addr)
cmdstr += "send\n"
cmdstr += "quit\n"
return cmdstr
def main():
ap = argparse.ArgumentParser(description="Update dynamic DNS records using RFC2136")
ap.add_argument("interface", help="interface to obtain IP from (for IPv6, takes the numerically first global address on the interface)")
ap.add_argument("record", help="DNS record to update")
ap.add_argument("zone", help="Zone name to update (e.g. example.com)")
ap.add_argument("server", help="Server to update (IP or FQDN)")
ap.add_argument("--v4", help="Update IPv4 A record", action="store_true", default=False)
ap.add_argument("--v6", help="Update IPv6 AAAA record (default)", action="store_true", default=True)
ap.add_argument("--addr4", help="Update A record with provided IP rather than detected IP (causes 'interface' to be ignored)")
ap.add_argument("--addr6", help="Update AAAA record with provided IP rather than detected IP (causes 'interface' to be ignored)")
ap.add_argument("--ttl", help="TTL to assign to record (default 300)", default=300)
ap.add_argument("--keyfile", help="Alternate location for key config file (default /etc/ddns-RECORD.key where RECORD is the record name provided as the argument)")
ap.add_argument("--debug", help="Enable debug logging", action="store_true", default=False)
args = ap.parse_args()
if args.debug:
log.setLevel(logging.DEBUG)
else:
log.setLevel(logging.ERROR)
if args.keyfile:
keyfile = args.keyfile
else:
keyfile = "/etc/ddns-{}.key".format(args.record)
log.debug("KEYFILE: {}".format(keyfile))
if args.v4:
addrtype = netifaces.AF_INET
else:
addrtype = netifaces.AF_INET6
ip = False
if args.addr4:
ip = build_ip(args.addr4)
if args.addr6:
ip = build_ip(args.addr6)
try:
if not os.path.exists(keyfile):
raise Exception("missing key file {}".format(keyfile))
if ip:
addr = ip
log.debug("Manual IP: {}".format(addr))
else:
addrarr = get_interface_addrs(args.interface, addrtype)
addr = addrarr.pop(0)['addr']
log.debug("Found IP: {}".format(addr))
rrtype = "AAAA"
if args.v4:
rrtype = "A"
nsupdatecmd = build_nsupdate_cmd(args.server, args.zone, args.record, rrtype, args.ttl, addr)
nsupdate = subprocess.run(
"nsupdate -k {}".format(keyfile),
shell=True,
check=True,
input = bytes(nsupdatecmd,'utf-8'),
capture_output = True
)
log.debug("nsupdate return code: {}".format(nsupdate.returncode))
except subprocess.CalledProcessError as e:
log.debug("Exception class: {}".format(e.__class__))
log.error("Error executing: " + e.cmd)
log.error("nsupdate stderr: " + e.stderr.decode("utf-8").strip())
sys.exit(1)
except Exception as e:
log.debug("Exception class: {}".format(e.__class__))
log.error(str(e))
sys.exit(1)
if __name__ == "__main__":
log = logging.getLogger("ddns-update-rfc2136")
lh = logging.StreamHandler()
lf = logging.Formatter(fmt='%(name)s: %(levelname)s: %(message)s')
lh.setFormatter(lf)
log.addHandler(lh)
main()
sys.exit(0)
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