But it is not always a case in the world of NATs and VPNs.
If machine always have public IP address, than using some dynamic DNS
-service may help (short of neccessity to use full domain name. But
+service may help (short of necessity to use full domain name. But
${HOME}/.ssh/config may help). But what if you log into your office
workstation via corporate VPN, and want ssh back home?
See [manual page](dyngo.md) for more info.
+PRROTOCOL
+=========
+
+**dyngo** uses protocol compatible with dyndns.org, as described
+pn [help.dyn.com](https://help.dyn.com/remote-access-api/perform-update/
+)
+As different dynamic DNS servers use different path components of URL,
+you should specify URL with path component (up to question mark) in
+the *server* parameter of configuraton section.
+
+INSTALLATION
+============
+
+**dyngo** is simple script which doesn't require anything but
+python3 with standard library and **ip** utility from iproute (or
+iproute2 on Debian) package, which presents on every modern Linux
+system.
+
+I've even preferred to use
+[urllib](https://docs.python.org/3/library/urllib.request.html#module-urllib.request)
+to [requests](http://docs.python-requests.org/) to eliminate extra
+external dependency.
+
+So, you can just drop **dyngo** somewhere in your filesystem, say in
+**/usr/local/sbin** and put config into */etc* But **dyngo** should run
+as a service, so you might want to use provided service file.
+
+**dyngo** should run as unprivileged user. But its configuration file
+should, readable for this user, contains somewhat sensitive information
+— your dyndns passwords. So, don't use common account many untrusted
+code run as such as **nobody** or **www-data**. Better to create special
+user dyngo.
+
+There should be writable directory, writable for this user for
+persistent state database. By default it is /var/lib/dyngo.
#!/usr/bin/env python3
import ipaddress, subprocess, sys, getopt,dbm
from configparser import ConfigParser
+import urllib.request,urllib.parse
+import logging,os.path,time
class DyndnsNetwork(object):
"""
This class represents dynamic DNS server and network.
self.hostname = config_section['hostname']
self.network = ipaddress.ip_network(config_section['network'])
self.server = config_section['server']
- if user in config_section:
+ if 'user' in config_section:
self.user=config_section["user"]
self.password=config_section["password"]
if self.network.version != address.version:
return False
return address in self.network
- def nsupdate(self, address):
- raise NotImplementedError
+ def nsupdate(self, address):
+ """
+ Sends a get query to specified server.
+ Raises HTTPError if something goes wrong
+ """
+ #construct opener
+ logging.debug("Going to send message to %s",self.server)
+ if hasattr(self,'user'):
+ password_mgr =urllib.request.HTTPPasswordMgrWithDefaultRealm()
+ password_mgr.add_password(None,self.server,self.user,self.password)
+ handler=urllib.request.HTTPBasicAuthHandler(password_mgr)
+ opener = urllib.request.build_opener(handler)
+ else:
+ opener = urllib.request.build_opener()
+ with opener.open('%s?%s'%(self.server,
+ urllib.parse.urlencode({'hostname':self.hostname,
+ 'myip':str(address)}))) as req:
+ req.read().decode("utf-8")
+
+
def get_current_addresses():
result=[]
+ logging.debug("Acquire current IPs")
for line in subprocess.run(['ip','-o','addr','show'],check=True,stdout=subprocess.PIPE).stdout.decode('utf-8').split("\n"):
if not len(line):
continue
if address.is_loopback or address.is_link_local:
continue
result.append(address)
+ logging.debug("Got following addresses: %s",repr(result))
return result
def check_for_update():
addrlist=get_current_addresses()
old_addr=ipaddress.ip_address(database[name].decode("utf-8"))
if old_addr==a:
# Nothing changed go, to next net
+ logging.debug("Address for net %s not changed",name)
break
# address changed
- net.nsupdate(a)
- database[name]=str(a)
+ try:
+ logging.info("Doing update for net %s with address %s",name, str(a))
+ net.nsupdate(a)
+ database[name]=str(a)
+ except urllib.error.HTTPError as e:
+ logging.exception("Http error doing nsupdate code %s",e.code)
+ break
if not found:
+ logging.info("Address for net %s no more found",name)
del data[name]
-
-
-
-config=ConfigPaser()
-config['dyngo']={'interval':'60','database','/var/lib/dyngo/dyngo.db'}
+config=ConfigParser()
+config['dyngo']={'interval':'60','database':'/var/lib/dyngo/dyngo.db',
+ 'ca':'/etc/ssl/certs','loglevel':'WARNING'}
options=dict(getopt.getopt(sys.argv,"f:")[0])
if not '-f' in options:
options["-f"]="/etc/dyngo.conf"
if len(config.read(options["-f"]))!=1:
print("Cannot read config %s"%options["-f"],file=sys.stderr)
sys.exit(1)
-
conf=config['dyngo']
+if conf['loglevel'].isdigit():
+ level=int(conf['loglevel'])
+else:
+ try:
+ logging.NOTICE=25
+ level=getattr(logging,conf['loglevel'].upper())
+ except AttributeError:
+ print("Invalid logleevel '%s'"%conf('loglevel'))
+ sys.exit(1)
+
+logging.basicConfig(format="%(asctime)s %(message)s",
+ level=level, stream=sys.stderr)
interval=int(conf['interval'])
database=dbm.open(conf['database'],"c")
+https_params={}
+if 'ca' in conf and len(conf['ca']):
+ path=conf['ca']
+ if os.path.isdir(path):
+ https_params['capath']=path
+ else:
+ http_params['cafile']=path
# Convert all other config sections to DyndnsNetwork objects
networks={}
for sect in config.sections():
- if sect == 'dyngo' or sect= 'DEFAULT':
+ if sect == 'dyngo' or sect == 'DEFAULT':
continue
+ logging.debug("Processing network %s",sect)
networks[sect]=DyndnsNetwork(config[sect])
# Remove stale items from persistent database, which are no more
# mentioned in the config file
-for i in set([x.decode("utf-8") for x database.keys()])-set(network.keys()):
+for i in set([x.decode("utf-8") for x in database.keys()])-set(networks.keys()):
+ logging.info("Removing from persistent state network %s which is no more in config",i)
del database[i]
-
while True:
check_for_update()
time.sleep(interval)
Names of server-description sections are arbitrary, but should be
unique, because they are used as keys into persistent database.
-
+Parameters of **dyngo** section
+-------------------------------
+
+* interval - number of seconds between rescans of network interfaces
+* database - path to persistent state database
+* ca - path to trusted certificate store in openssl compatible format.
+* loglevel - minimum log message level which shoud to console
+
+Parameters of network section
+-----------------------------
+
+* **hostname** - fully qualified domain name of your host to register in DNS
+* **network** - network in *address*/*bits* notation which this host
+should belong to. If we see address from this network on one of our
+interfaces, we would send request to corresponding server. If net is
+not privatte, but include private ranges, i.e. 0.0.0.0/0 or ::/0 private
+addresses are not considered part of it.
+* **server** - full url (without query string) of the dyndns web handler.
+* **user** - user name for HTTP basic authentication
+* **password** - password for HTTP basic authentcircation
projects / oss / dyngo.git / commitdiff