Web Server

The Netdata Web Server is static-threaded, with a fixed, configurable number of threads.

All the threads are concurrently listening for web requests on the same sockets, and the kernel distributes the incoming requests to them. Each thread uses non-blocking I/O so it can serve any number of web requests in parallel.

It respects the keep-alive HTTP header to serve multiple HTTP requests via the same connection.

Configuration

Edit netdata.conf using the edit-config script

Scroll down to the [web] section to find the following settings.

Settings

Setting	Default	Description
ssl key	/etc/netdata/ssl/key.pem	Declare the location of an SSL key to enable HTTPS.
ssl certificate	/etc/netdata/ssl/cert.pem	Declare the location of an SSL certificate to enable HTTPS.
tls version	1.3	Choose which TLS version to use. While all versions are allowed (1 or 1.0, 1.1, 1.2 and 1.3), we recommend 1.3 for the most secure encryption. If left blank, Netdata uses the highest available protocol version on your system.
tls ciphers	none	Choose which TLS cipher to use. Options include TLS_AES_256_GCM_SHA384, TLS_CHACHA20_POLY1305_SHA256, and TLS_AES_128_GCM_SHA256. If left blank, Netdata uses the default cipher list for that protocol provided by your TLS implementation.
ses max window	15	See single exponential smoothing.
des max window	15	See double exponential smoothing.
mode	static-threaded	Turns on (static-threaded) or off (none) the static-threaded Web Server. See the example to turn off the Web Server and disable the dashboard.
listen backlog	4096	The port backlog. Check man 2 listen.
default port	19999	The listen port for the static Web Server.
web files owner	netdata	The user that owns the web static files. Netdata will refuse to serve a file that is not owned by this user, even if it has read access to that file. If the user given is not found, Netdata will only serve files owned by user given in run as user.
web files group	netdata	If this is set, Netdata will check if the file is owned by this group and refuse to serve the file if it's not.
disconnect idle clients after	1m	The time in seconds to disconnect web clients after being totally idle.
timeout for first request	1m	How long to wait for a client to send a request before closing the socket. Prevents slow request attacks.
accept a streaming request every	off	Can be used to set a limit on how often a Parent will accept streaming requests from Children in a streaming and replication setup.
respect do not track policy	no	If set to yes, Netdata will respect the user's browser preferences for Do Not Track (DNT) and storing cookies. If DNT is enabled in the browser, and this option is set to yes, nodes will not connect to any registry. For certain browsers, users must disable DNT and change this option to yes for full functionality.
x-frame-options response header	``	Avoid clickjacking attacks, by ensuring that the content is not embedded into other sites.
allow connections from	localhost *	Declare which IP addresses or full-qualified domain names (FQDNs) are allowed to connect to the Web Server, including the dashboard or HTTP API. This is a global setting with higher priority to any of the ones below.
allow connections by dns	heuristic	See the access list section for details on using allow settings.
allow dashboard from	localhost *
allow dashboard by dns	heuristic
allow badges from	*
allow badges by dns	heuristic
allow streaming from	*
allow streaming by dns	heuristic
allow netdata.conf	localhost fd* 10.* 192.168.* 172.16.* 172.17.* 172.18.* 172.19.* 172.20.* 172.21.* 172.22.* 172.23.* 172.24.* 172.25.* 172.26.* 172.27.* 172.28.* 172.29.* 172.30.* 172.31.* UNKNOWN
allow netdata.conf by dns	no
allow management from	localhost
allow management by dns	heuristic
enable gzip compression	yes	When set to yes, Netdata web responses will be GZIP compressed, if the web client accepts such responses.
gzip compression strategy	default	Valid settings are default, filtered, huffman only, rle and fixed.
gzip compression level	3	Valid settings are 1 (fastest) to 9 (best ratio).
web server threads	``	How many processor threads the web server is allowed. The default is system-specific, the minimum of 6 or the number of CPU cores.
web server max sockets	``	Available sockets. The default is system-specific, automatically adjusted to 50% of the max number of open files Netdata is allowed to use (via /etc/security/limits.conf or systemd), to allow enough file descriptors to be available for data collection.
custom dashboard_info.js	``	Specifies the location of a custom dashboard.js file. See customizing the standard dashboard for details.

Access lists

Netdata supports access lists in netdata.conf:

[web]
    allow connections from = localhost *
    allow dashboard from = localhost *
    allow badges from = *
    allow streaming from = *
    allow netdata.conf from = localhost fd* 10.* 192.168.* 172.16.* 172.17.* 172.18.* 172.19.* 172.20.* 172.21.* 172.22.* 172.23.* 172.24.* 172.25.* 172.26.* 172.27.* 172.28.* 172.29.* 172.30.* 172.31.*
    allow management from = localhost

* does string matches on the IPs or FQDNs of the clients.

• allow connections from matches anyone that connects on the Netdata port(s). So, if someone is not allowed, it will be connected and disconnected immediately, without reading even a single byte from its connection. This is a global setting with higher priority to any of the ones below.

• allow dashboard from receives the request and examines if it is a static dashboard file or an API call the dashboards do.

• allow badges from checks if the API request is for a badge. Badges aren’t matched by allow dashboard from.

• allow streaming from checks if the child willing to stream metrics to this Netdata is allowed. This can be controlled per API KEY and MACHINE GUID in stream.conf. The setting in netdata.conf is checked before the ones in stream.conf.

• allow netdata.conf from checks the IP to allow http://netdata.host:19999/netdata.conf. The IPs listed are all the private IPv4 addresses, including link-local IPv6 addresses. Keep in mind that connections to Netdata API ports are filtered by allow connections from. So, IPs allowed by allow netdata.conf from should also be allowed by allow connections from.

• allow management from checks the IPs to allow API management calls. Management via the API is currently supported for health

To check the FQDN of the connection without opening the Netdata Agent to DNS-spoofing, a reverse-dns record must be setup for the connecting host. At connection time, the reverse-dns of the peer IP address is resolved, and a forward DNS resolution is made to validate the IP address against the name-pattern.

Please note that this process can be expensive on a machine that is serving many connections. Each access list has an associated configuration option to turn off DNS-based patterns completely to avoid incurring this cost at run-time:

    allow connections by dns = heuristic
    allow dashboard by dns = heuristic
    allow badges by dns = heuristic
    allow streaming by dns = heuristic
    allow netdata.conf by dns = no
    allow management by dns = heuristic

The three possible values for each of these options are yes, no and heuristic. The heuristic option disables the check when the pattern only contains IPv4/IPv6 addresses or localhost, and enables it when wildcards are present that may match DNS FQDNs.

DDoS protection

If you publish your Netdata web server to the internet, you may want to apply some protection against DDoS:

1. Use the static-threaded web server (it is the default)
2. Use reasonable [web].web server max sockets (e.g default)
3. Don't use all your CPU cores for Netdata (lower [web].web server threads)
4. Run the netdata process with a low process scheduling priority (the default is the lowest)
5. If possible, proxy Netdata via a full-featured web server (Nginx, Apache, etc.)

Examples

Disable the Web Server

details

Edit netdata.conf using the edit-config script

[web]
    mode = none

Change the number of threads

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Control the number of threads and sockets with the following settings:

[web]
    web server threads = 4
    web server max sockets = 512

Binding Netdata to multiple ports

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Netdata can bind to multiple IPs and ports, offering access to different services on each. Up to 100 sockets can be used (increase it at compile time with CFLAGS="-DMAX_LISTEN_FDS=200" ./netdata-installer.sh ...).

The ports to bind are controlled via [web].bind to, like this:

[web]
   default port = 19999
   bind to = 127.0.0.1=dashboard^SSL=optional 10.1.1.1:19998=management|netdata.conf hostname:19997=badges [::]:19996=streaming^SSL=force localhost:19995=registry *:http=dashboard unix:/run/netdata/netdata.sock

Using the above, Netdata will bind to:

• IPv4 127.0.0.1 at port 19999 (port was used from default port). Only the UI (dashboard) and the read API will be accessible on this port. Both HTTP and HTTPS requests will be accepted.
• IPv4 10.1.1.1 at port 19998. The management API and netdata.conf will be accessible on this port.
• All the IPs hostname resolves to (both IPv4 and IPv6 depending on the resolved IPs) at port 19997. Only badges will be accessible on this port.
• All IPv6 IPs at port 19996. Only metric streaming requests from other Netdata Agents will be accepted on this port. Only encrypted streams will be allowed (i.e., Children also need to be configured for TLS).
• All the IPs localhost resolves to (both IPv4 and IPv6 depending on the resolved IPs) at port 19996. This port will only accept registry API requests.
• All IPv4 and IPv6 IPs at port http as set in /etc/services. Only the UI (dashboard) and the read API will be accessible on this port.
• Unix domain socket /run/netdata/netdata.sock. All requests are serviceable on this socket. Note that in some OSs like Fedora, every service sees a different /tmp, so don't create a Unix socket under /tmp. /run or /var/run is suggested.

The option [web].default port is used when entries in [web].bind to do not specify a port.

As shown in the example above, these permissions are optional, with the default permitting all request types on the specified port.

The request types are strings identical to the allow X from directives of the access lists, i.e. dashboard, streaming, registry, netdata.conf, badges and management. The access lists themselves and the general setting allow connections from in the next section are applied regardless of the ports that are configured to provide these services.

The API requests are serviced as follows:

• dashboard gives access to the UI, the read API and badges API calls.
• badges gives access only to the badge API calls.
• management gives access only to the management API calls.

Enable HTTPS/TLS support

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Since v1.16.0, Netdata supports encrypted HTTP connections to the web server, plus encryption of streaming data to a parent from its child nodes, via the TLS protocol.

Inbound unix socket connections are unaffected, regardless of the TLS settings.

While Netdata uses Transport Layer Security (TLS) 1.2 to encrypt communications rather than the obsolete SSL protocol, it's still common practice to refer to encrypted web connections as SSL. Many vendors, like Nginx and even Netdata itself, use SSL in configuration files, whereas documentation will always refer to encrypted communications as TLS or TLS/SSL.

To enable TLS, provide the path to your certificate and private key in the [web] section of netdata.conf:

[web]
    ssl key = /etc/netdata/ssl/key.pem
    ssl certificate = /etc/netdata/ssl/cert.pem

Both files must be readable by the netdata user. If any of these files are missing or can’t be read, Netdata will fall back to using HTTP. For a parent-child connection, only the parent needs these settings.

For test purposes, generate self-signed certificates with the following command:

openssl req -newkey rsa:2048 -nodes -sha512 -x509 -days 365 -keyout key.pem -out cert.pem

If you use 4096 bits for your key and the certificate, Netdata will need more CPU to process the communication. rsa4096 can be up to four times slower than rsa2048, so we recommend using 2048 bits. Verify the difference by running:

openssl speed rsa2048 rsa4096

Select TLS version

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Beginning with version v1.21.0, specify the TLS version and the ciphers that you want to use:

[web]
    tls version = 1.3
    tls ciphers = TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256

If you don’t specify these options, Netdata will use the highest available protocol version on your system and the default cipher list for that protocol provided by your TLS implementation.

TLS/SSL enforcement

When the certificates are defined and unless any other options are provided, a Netdata server will:

• Redirect all incoming HTTP web server requests to HTTPS. Applies to the dashboard, the API, netdata.conf and badges.
• Allow incoming child connections to use both unencrypted and encrypted communications for streaming.

To change this behavior, you need to modify the bind to setting in the [web] section of netdata.conf. At the end of each port definition, append ^SSL=force or ^SSL=optional. What happens with these settings differs, depending on whether the port is used for HTTP/S requests or for streaming.

SSL setting	HTTP requests	HTTPS requests	Unencrypted Streams	Encrypted Streams
none	Redirected to HTTPS	Accepted	Accepted	Accepted
force	Redirected to HTTPS	Accepted	Denied	Accepted
optional	Accepted	Accepted	Accepted	Accepted

Example:

[web]
    bind to = *=dashboard|registry|badges|management|streaming|netdata.conf^SSL=force

For information how to configure the child to use TLS, check securing the communication in the streaming documentation. There you will find additional details on the expected behavior for client and server nodes, when their respective TLS options are enabled.

When we define the use of SSL in a Netdata Agent for different ports, Netdata will apply the behavior specified on each port. For example, using the configuration line below:

[web]
    bind to = *=dashboard|registry|badges|management|streaming|netdata.conf^SSL=force *:20000=netdata.conf^SSL=optional *:20001=dashboard|registry

Netdata will:

• Force all HTTP requests to the default port to be redirected to HTTPS (same port).
• Refuse unencrypted streaming connections from child nodes on the default port.
• Allow both HTTP and HTTPS requests to port 20000 for netdata.conf
• Force HTTP requests to port 20001 to be redirected to HTTPS (same port). Only allow requests for the dashboard, the read API and the registry on port 20001.

TLS/SSL errors

When you start using Netdata with TLS, you may find errors in the Netdata log, which is stored at /var/log/netdata/error.log by default.

Most of the time, these errors are due to incompatibilities between your browser's options related to TLS/SSL protocols and Netdata's internal configuration. The most common error is error:00000006:lib(0):func(0):EVP lib.