“UbuntuHelp:DynamicDNS”的版本间的差异

2008年11月25日 (二) 00:42的版本

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https://help.ubuntu.com/community/DynamicDNS

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Parent page: Internet and Networking

Dynamic DNS

Every computer which is attached to the internet has an IP address. DNS is the process of relating a name to an IP address so that a website or other service can be accessed using an easily-remembered named (like 'www.google.com'), rather than a number (like '192.168.0.1'). Most servers on the internet have a fixed IP address that never changes. This means that a 'static' DNS record can be set once such that it always redirects the DNS name to right place. However, most home users will be assigned a dynamic IP address that will change periodically, or each time they connect to the internet. In the past this made it very difficult to make a home computer accessible from the broader Internet. But with an increasing number of "Dynamic DNS" service providers, this is not such a problem. Dynamic DNS services offer you a DNS entry with a hostname of your choice. You are then responsible for updating the DNS entry whenver your IP address changes. This pages gives details about how to do that.

Registering with a Dynamic DNS provider

Dynamic DNS requires that a server somewhere on the internet keep track of 'where you are'. That is, it records your host name, and records what the IP address is that corresponds to your hostname. Many Dynamic DNS provider offer a free service with a limited range of hostnames to choose from. Paid services will permit a larger selection of hostnames, including use of your own registered domain name. So before you can get started using Dynamic DNS, you'll need to register with one of these such services. Here is a selection:

• dyndns.com
• no-ip
• zoneedit
• easy DNS
• Afraid.org (free)

Upon registering, you will be provided with username and password, as well a hostname that you will be using as the DNS name that will allow external access to your machine.

Set up DNS Notification

Now that you have a DNS provider, you need to set up a way that your IP address will be updated whenever it is changed. There are two ways of doing this:

• using the built-in capabilities of your Cable/DSL modem or Router
• using dynamic DNS software that you install on your computer

Try first to find out if your modem/router supports Dynamic DNS reporting/notification/updating. If your modem has a built-in 'website' you may find the necessary information by entering its IP address into your browser, for example http://10.1.1.1/ or http://192.168.01/ However, even if your modem/router does support dynamic DNS reporting, there are cases where you will need to use the second approach: perhaps you modem/router is too old, or perhaps you want the DNS entry to follow your *computer* around, rather than stay with your DSL/Cable connection.

Using your Computer to perform Dynamic DNS Notification

There are several alternatives. You may need to add the Ubuntu Universe to your set of software repositories. See InstallingSoftware for all the details.

inadyn

Install the inadyn package using Synaptic Package manager, then: The following will allow your Ubuntu Linux machine to be accessible anywhere that you are given an externally-accessible IP address. This includes most ISPs but excludes many office LANs. First edit the file /etc/inadyn.conf:

gksudo gedit /etc/inadyn.conf

It should contain something like to the following:

--username myusername
--password mypassword
--update_period 60000
--alias myhost.dyndns.org
--background

Now test that it works by typing

sudo /usr/sbin/inadyn

Next, add inadyn to your 'crontab':

export EDITOR=gedit
sudo crontab -e

Edit the file to add the following additional line:

@reboot /usr/sbin/inadyn

Then save and exit the editor. Verify using

sudo crontab -l

When you reboot, you should see indyn listed when you type

ps -A | grep inadyn

You should be able to log in to your Dynamic DNS provider's website and verify that the DNS entry is being updated. Certainly this is possible with www.dyndns.org, in any case. Alternatively you can type your hostname into a service like http://www.dnsstuff.com/.

ddclient

More details required here. The documentation is good however, and there is a Ubuntu package for ddclient in the Ubuntu Universe. Install ddclient and the package installer scripts will ask you for your information. http://ddclient.sourceforge.net/?page=0

The following instructions is a wiki formatted excerpt from the ubuntu-users mailing list on the issue of repairing a ddclient setup: http://linux.derkeiler.com/Mailing-Lists/Ubuntu/2007-12/msg01412.html Author: Unknown 1. Remove/purge all of the previous install attempts:

sudo apt-get remove --purge ddclient

2. Install ssh & ssh socket so that you can send your password via ssh instead of in the clear:

sudo apt-get install ssh libio-socket-ssl-perl

Note: ssh w/ddclient won't work without libio-socket-ssl-perl, so make sure that you install that even if you have ssh already installed. 2. Reinstall ddclient from the repo:

sudo apt-get install ddclient

At the prompts enter the appropriate values, for example: Dynamic DNS service provider: www.dyndns.com DynDNS fully qualified domain names: your-hostname.dyndns.org Username for dynamic DNS service: your-username Password: your-password Enter the interface which is used for using dynamic DNS service: web 3. Modify the /etc/ddclient.conf to send the password using ssh and to properly check for the IP address:

gksu gedit /etc/ddclient.conf

Add entries for "daemon", "ssl" and replace "use=if, if=web" with "use=web" to match the following example:

# Configuration file for ddclient generated by debconf
#
# /etc/ddclient.conf

daemon=300
pid=/var/run/ddclient.pid
ssl=yes
use=web, web=checkip.dyndns.com/, web-skip='IP Address'
login=your-username
password=your-password
protocol=dyndns2
server=members.dyndns.org
your-hostname.dyndns.org

Reference for secure updates: https://www.dyndns.com/support/kb/using_ddclient_with_dyndns_services.html Now ddclient is set to run as a daemon. Because you had other ddclient configs previously, check:

gksu gedit /etc/default/ddclient

Check to make sure it contains the following lines:

run_ipup="false"
run_daemon="true"
daemon_interval="300"

Note: you can set the interval shorter or longer, but if you do, also reset your /etc/ddclient.conf to match. https://bugs.launchpad.net/ubuntu/+source/ddclient/+bug/152875 Now, just to be sure everything sticks I generally reboot at this point, then check the status afterwards:

sudo /etc/init.d/ddclient status

You should see:

Status of Dynamic DNS service update utility: ddclient is running

However, that may not always catch problems in the ddclient.conf file, so issue:

sudo /etc/init.d/ddclient restart

if you do not get an error similar to the following you probably are good to go:

WARNING: file /etc/ddclient.conf, line x

Then I obtain a new IP address/lease from my service provider (shutting off the modem, having my router request a new lease, whatever) & monitor https://www.dyndns.com/account/services/hosts/ to see if the change actually makes it to dyndns. Also monitor /var/log/syslog to watch the changes there as well.

no-ip

This is another Dynamic DNS reporting client.

sudo no-ip -C
Please enter the login/email string for no-ip.com: <your_login>
Please enter the password for user 'your_login': <your_password>
Please enter an update interval:[30] <interval time in minutes>
Do you wish to run something at successful update?[N] <N>

Next, start the no-ip client

sudo no-ip

Using your Modem/Router for Dynamic DNS Reporting

Here are some example screenshots from Wireless Routers that support dynamic DNS reporting: Example: Another example: Yet another example: with port forwarding: