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Hostname

C2N is a free service giving you a hostname at the internet domain "c2n.uk".

Hostnames are used to identify computers on the internet. A computer can host a web site and using its hostname is how we locate that service.

The hostname will be exactly as your login name, so for example, if you were to sign up as `example' then your hostname would be example at the C2N domain c2n.uk.

With C2N you can set up your own personal server at home, such as a web server, and allow internet clients to gain access to its content using your hostname at the C2N domain.

A internet domain is used for publishing the addresses of related computers in the domain name system (DNS). Each computer is a member of the domain with its own individual hostname entry.

C2N hostnames are registered at the C2N domain name system (DNS) servers. The DNS servers answer queries from the internet about the locations of hostnames and if they exist, will reply with their Internet protocol (IP) address.

Internet protocol (IP) addresses are used by computers to find eachother on the Internet. IP addresses are similar to phone numbers and are used to connect one machine to another.

An IP address can come in one of two varieties, version 4 (IPv4) and version 6 (IPv6). IPv4 is the 32-bit legacy numbering scheme and IPv6 is the 128-bit replacement for IPv4. Not all internet service providers (ISPs) support IPv6 at this time but are expected to do so eventually.

When you visit this site you will be either using IPv4 or IPv6, this is detected by the server and the hostname IP address is set appropriately in the DNS either when C2N is initialised or an C2N administration page update is performed.

If you are using IPv6, then your connection is most likely dual-stack compatible. This means you have the capability of either using IPv6 or IPv4. In this situation you may access the site with IPv6 but prefer IPv4 for your host. Using a command line tool on your host can set an IPv4 address for your hostname, however, if your connection uses dual-stack `lite' then only IPv6 will allow a connection to your home network.

Static IPv6 addresses may be assigned by your ISP on a per customer account or location basis. For IPv4, a static address would normally be arranged between the customer and the ISP. A single DNS update is required on our server to configure the IP address of your host if it uses a static address.

Dynamic IP addressing is commonly used by ISPs for both IPv6 and IPv4. With IPv6 a dynamic address prefix is used and for IPv4 a dynamic address. This address changes when your router connects and reconnects to the internet. For this situation C2N has a service called Dynamic DNS which can be used update the server whenever the router address changes.

If your IP address is static you can set your hostname address by visiting the C2N administration page and then update it. The page should correctly detect your client address. If the address is not correct, for example, because you are not on the target host you can instead run a simple command on your host to set the address. This will require entering a hostname password on the administation page first.

This update uses `curl' which you may need to install.

curl -s "http://example:PASSWORD@ipvX.runstop.uk/ddns/?hostname=example.c2n.uk"

Replace example with your login, PASSWORD with the chosen hostname password and replace ipvX with ipv4 or ipv6 as appropriate.

Dynamic DNS depends on a client you may run on your host or DD-WRT powered router which periodically determines the ADSL or cable IP address of your home network and then connects to a server to publish that address when it changes.

The C2N domain runs a dynamic DNS service which has been tested to be compatible with `ddclient' for Raspbian on the Pi and `inadyn' with DD-WRT when using IPv4.

Here is an example configuration for ddclient.

# /etc/ddclient.conf
daemon=3600
foreground=no
protocol=dyndns2
use=web
login=example
password=PASSWORD
server=cgi.runstop.uk
script=/ddns/
ssl=no
example.c2n.uk

DDNS on DD-WRT has been tested to work with this set up.

DDNS Service: Custom
DYNDNS Server: cgi.runstop.uk
User Name: example
Password: PASSWORD
Host Name: example.c2n.uk
URL: /ddns/?hostname=

Where it says `example' above, replace that with your login, likewise replace `PASSWORD' with your hostname password. The hostname password is set on the C2N administration page and is not the login password used to access this site.

Once your address is set on the domain name system server a personal server can then be installed on your host. For the internet to access this service, this access will need to be permitted on your ADSL or cable modem router.

Generally an ADSL or cable modem router will disallow access from the internet to an internal host hence one of two methods must be utilised to allow this.

For IPv4, port forwarding on the router will relay access from the internet to an internal device on your network.

For IPv6, rather then port forwarding, an access filter will be opened to allow the internet to pass through.

Since each router has its own methods and means of providing access you must consult the technical guide of your device in order to achieve this.

Normally a router will have an administration page that allows the selection of an external port and then an internal destination address. For an internal personal web service on port 80 (HTTP protocol) you would relay port 80 from the internet to your internal host.

With both the domain name system service and router access operational you can run a personal server on a Pi, such as the apache2 web server, to service the internet.

Apache will allow you to create a completely customised web site to deliver your content to internet clients.