dness

Finesse with dness: a dynamic dns client

---

Motivation

When one has a server that is subjected to unpredictable IP address changes, such as at home or elsewhere, a change in IP address causes unexpected downtime. Instead of paying for a static IP address, one can employ a dynamic dns client on said server, which will update the WAN IP address on the dns server.

There are plenty of dynamic dns clients, including the venerable ddclient, but troublesome installation + perl system dependency resolution, and cache format errors have left much to be desired. Other solutions fall short, so dness was created with the following goals:

Goals:

• Cross platform (Windows, Mac, Linux, ARM, BSD)
• "zero" dependencies
  • Depend on only already installed system wide dependencies (libssl (eg: openssl))
  • And offer statically linked builds for truly zero dependencies
• A standard configuration (TOML) that is similar to ddclient's.
• Extendable to allow for more dynamic dns services
• Sensible logging to glean insight into inevitable problems that arise with networked services
• Permissively licensed

Installation

To maximize initial flexibility, dness is not a daemon. Instead it relies on the host's scheduling (cron, systemd timers, windows scheduler).

Ubuntu / Debian (systemd + deb)

• Decide if you want a static musl package or one that depends on the system's openssl.
• Download the latest chosen deb

dpkg -i dness<version>_amd64.deb

# ensure it is working
/usr/bin/dness

# enable systemd timer
systemctl daemon-reload
systemctl start dness.timer
systemctl enable dness.timer

# update configuration
${EDITOR:-vi} /etc/dness/dness.conf

Linux Musl

The linux musl build is a static build of dness. It has zero dependencies. Nothing is quite like scp'ing or curl'ing a musl binary to a random / unknown linux server and having it just work.

• Download the latest "-x86_64-unknown-linux-musl.tar.gz"
• untar (tar -xzf *-x86_64-unknown-linux-musl.tar.gz)
• enjoy

Windows

• Download the latest ".exe"
• Create configuration file (dness.conf)
• Execute dness.exe -c dness.conf to verify behavior
• If desired, use windows task scheduler to execute command at specific times

Other

Download the latest appropriate target

Configuration

No configuration file is necessary when only the WAN IP is desired.

./dness

Sample output:

[INFO  trust_dns_proto::xfer::dns_exchange] sending message via: UDP(208.67.220.220:53)
[INFO  dness] resolved address to 256.256.256.256 in 23ms
[INFO  dness] processed all: (updated: 0, already current: 0, missing: 0) in 29ms

Sample Configuration

But dness can do more than resolve one's WAN IP. Below is a sample configuration (dness.conf) that should cover most needs:

[log]
# How verbose the log is. Common values: Error, Warn, Info, Debug, Trace
level = "Debug"

[[domains]]
# We denote that our domain is managed by cloudflare
type = "cloudflare"

# The email address registered in cloudflare that is authorized to update dns
# records
email = "admin@example.com"

# The cloudflare key can be found in the domain overview, in "Get your API key"
# and view "Global API Key" (or another key as appropriate)
key = "deadbeef"

# The zone is the domain name
zone = "example.com"

# List of A records found under the DNS tab that should be updated
records = [
    "n.example.com"
]

# More than one domain can be specified in a config!
[[domains]]
type = "cloudflare"
email = "admin@example.com"
key = "deadbeef"
zone = "example2.com"
records = [
    "n.example2.com",
    "n2.example2.com"
]

Execute with configuration:

./dness -c dness.conf

Supported Dynamic DNS Services

Cloudflare

[[domains]]
# We denote that our domain is managed by cloudflare
type = "cloudflare"

# The email address registered in cloudflare that is authorized to update dns
# records
email = "admin@example.com"

# The cloudflare key can be found in the domain overview, in "Get your API key"
# and view "Global API Key" (or another key as appropriate)
key = "deadbeef"

# The zone is the domain name
zone = "example.com"

# List of A records found under the DNS tab that should be updated
records = [
    "n.example.com"
]

Cloudflare dynamic dns service works in three steps:

1. Send GET to translate the zone (example.com) to cloudflare's id
2. Send GET to find all the domains under the zone and their sub-ids
   • Cloudflare paginates the response to handle many subdomains
   • It is possible to query for individual domains but as long as more than one desired domain in each page -- this methods cuts down requests
3. Each desired domain in the config is checked to ensure that it is set to our address. In this way cloudflare is our cache (to guard against nefarious users updating out of band)

GoDaddy

[[domains]]
# denote that the domain is managed by godaddy
type = "godaddy"

# The GoDaddy domain: https://dcc.godaddy.com/domains/
domain = "example.com"

# This is the api key, you can create one here:
# https://developer.godaddy.com/keys
key = "abc123"

# The password for the key, top secret!
secret = "ef"

# The records to update. "@" = "example.com", "a" = "a.example.com"
records = [ "@", "a" ]

GoDaddy dynamic dns service works as the following:

1. Send a GET request to find all records in the domain
2. Find all the expected records (and log those that are missing) and check their current IP
3. Update the remote IP as needed, ensuring that original properties are preserved in the upload, so that we don't overwrite a property like TTL.

Supported WAN IP Resolvers

No other WAN IP resolvers are available, but it certainly possible to add other DNS or HTTP resolvers in the future.

OpenDNS

No configuration option are available for OpenDNS. It resolves IPv4 addresses by querying "myip.opendns.com" against resolver1.opendns.com and resolver2.opendns.com.