Synchronet v3.19b-Win32 (install) has been released (Jan-2022).

You can donate to the Synchronet project using PayPal.

Dynamic DNS

The Synchronet Dynamic DNS module is used in combination with the Synchronet Dynamic Domain Name System (DynDNS) Service hosted on Vertrauen to provide free hostnames to Synchronet sysops.

If you'd like a hostname, I offer a free, very easy-to-use dynamic hostname service exclusively for Synchronet sysops. Your hostname will always point to your current IP address, as long as your BBS is running. Using this service requires Synchronet v3.10 or later.


1. If you don't already have the exec/dyndns.js file, download the file into your Synchronet exec directory.

2. If you haven't already, create a QWK networking account on Vertrauen using your BBS's QWK-ID for the username (see this howto for more details).

Note: You do not have to actually join DOVE-Net to get a hostname, if you do not wish.

3. If you don't already have one, setup a timed event (in SCFG->External Programs->Timed Events) to run the command-line ?dyndns yourpass periodically, where yourpass is the password you used when you created your QWK networking account on Vertrauen. “DYNDNS” is the suggested internal code to use for this event.

If you have a frequently changing IP address (and Synchronet v3.11 or later) set “Always Run After Init/Re-init” to “Yes”. With this option set to “Yes”, frequent timed updates should not be necessary.

If you have a static IP address, one run (update) per month should be sufficient.

:!: Make sure that “Enabled” is set to “Yes”.

4. After saving your changes in SCFG, and verifying that the Terminal Server has recycled, check the event log window or console output to verify that the “DYNDNS” event has executed. You can force the event to execute with the (Win32) SBBSCTRL:BBS->Force Timed Event menu option, or by “touching” (creating or modifying) the file data/

5. Attempt to ping or connect to services at, where your-id is your BBS's QWK-ID. It may take a few minutes for a new hostname to become active or for an existing hostname to resolve to a newly changed IP address.

You're ready to go with your new hostname :!:


If you choose to include any dyndns.js command-line options, they must follow your password (and a space) on the configured command-line.

-mx [hostname]

DNS MX (mail exchange) resource records are used to designate a specific hostname as the “mail exchange” (receiving SMTP server) for a specific hostname. If there is no MX record, then the hostname itself is assumed to perform the role of “mail exchange”. Some receiving SMTP servers now require that the *sending* SMTP server correspond to the MX record of the “from” hostname. If you want to specify an MX record for your hostname, you can do so by adding -mx (optionally followed by a hostname) to your ?dyndns command-line (after the password). If no hostname is specified, then an MX record pointing back to your hostname will be created. Example: ?dyndns password -mx

-hn <base_hostname>

If you want to update a hostname that is different than your BBS's QWK-ID, ou can specify that hostname (QWK-ID) on the ?dyndns command-line (after the password) by using the -hn option followed by the hostname to use (not including “”). There must be a corresponding QWKnet account on Vertrauen for the specified hostname and password.

-ip6 [ipv6_address]

If you have a public IPv6 address, you may create/update a AAAA record along with your IPv4 A record by including the -ip6 option followed by a space and your current public IPv6 address. Vertrauen cannot at this time automatically detect your public IPv6 address, so if your IPv6 address changes, you will need to change the command-line accordingly.


If for some reason you want to specify a different IPv4 address than the one that your BBS will be using to connect with Vertrauen, you can include that IP address on the “?dyndns” command-line (after the password). This is an advanced feature that you should not need to use under normal conditions, even if your BBS is behind a firewall/router using network address translation (NAT) - the DynDNS server running on Vertrauen uses your correct public IP address by default.


Due to command-line length limits (63 characters), you may want to move one or more of the longer command-line options to the [dyndns] section of your ctrl/modopts.ini file.

The following options/keys are supported:

Key Record Description
mx MX Mail Exchange record (hostname)
ip A IP version 4 address (e.g.
ip6 AAAA IP version 6 address (e.g. 2607:f8b0:4007:801::200e)
txt TXT Text (default: BBS name)
loc LOC Location coordinates (see for details)
wildcard CNAME When set to true, will create a wildcard record for “*”

See Also