PROTO_WS module

Admin Guide

Overview

The WebSocket protocol (RFC 6455) provides an end-to-end full-duplex communication channel between two web-based applications. This allows WebSocket enabled browsers to connect to a WebSocket server and exchange any type of data. RFC 7118 provides the specifications for transporting SIP messages over the WebSocket protocol.

The proto_ws module is transport module that provides communication over the WebSocket protocol. This module is fully compliant with the RFC 7118, thus allowing browsers to act as SIP clients for the OpenSIPS proxy.

The current implementation acts both as WebSocket server and client, thus it can accept connections from WebSocket clients and can also initiate connections to another WebSocket server. After the connection is established, messages can flow in both directions.

OpenSIPS supports the following WebSocket operations:

• text and binary - can both send and receive WebSocket messages that contain text or binary body
• close - messages used to safely close the WebSocket communication using a 2-messages handshake
• ping - responds with pong messages. There is no mechanism to trigger ping messages.
• pong - sent when a ping message is received. OpenSIPS, absorbes the pong messages received.

Once loaded, you will be able to define WebSocket listeners in your script. To add a listener, you have to add its IP, and optionally the listening port, after the mpath parameter, similar to this example:

...
mpath=/path/to/modules
...
socket=ws:127.0.0.1    # change with the listening IP
socket=ws:127.0.0.1:5060  # change with the listening IP and port
...

Dependencies

OpenSIPS Modules

The following modules must be loaded before this module:

• None.

External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

• None.

Exported Parameters

ws_port (integer)

The default port to be used for all WS related operation. Be careful as the default port impacts both the SIP listening part (if no port is defined in the WS listeners) and the SIP sending part (if the destination WS URI has no explicit port).

If you want to change only the listening port for WS, use the port option in the SIP listener defintion.

Default value is 80.

Set ws_port parameter

...
modparam("proto_ws", "ws_port", 8080)
...

ws_send_timeout (integer)

Time in milliseconds after a WebSocket connection will be closed if it is not available for blocking writing in this interval (and OpenSIPS wants to send something on it).

Default value is 100 ms.

Set ws_send_timeout parameter

...
modparam("proto_ws", "ws_send_timeout", 200)
...

ws_max_msg_chunks (integer)

The maximum number of chunks in which a SIP message is expected to arrive via WebSocket. If a received packet is more fragmented than this, the connection is dropped (either the connection is very overloaded and this leads to high fragmentation - or we are the victim of an ongoing attack where the attacker is sending very fragmented traffic in order to decrease server performance).

Default value is 4.

Set ws_max_msg_chunks parameter

...
modparam("proto_ws", "ws_max_msg_chunks", 8)
...

trace_destination (string)

Trace destination as defined in the tracing module. Currently the only tracing module is proto_hep. Network events such as connect, accept and connection closed events shall be traced along with errors that could appear in the process. For each connection that is created an event containing information about http request and reply belonging to web socket protocol handshake and network layer information shall be sent.

Danger

A tracing module must be loaded in order for this parameter to work. (for example proto_hep).

Default value is none(not defined).

Set trace_destination parameter

...
modparam("proto_hep", "hep_id", "[hep_dest]10.0.0.2;transport=tcp;version=3")

modparam("proto_ws", "trace_destination", "hep_dest")
...

trace_on (int)

This controls whether tracing for ws is on or not. You still need to define trace destinationin order to work, but this value will be controlled using mi function mi ws trace.

Set trace_on parameter

...
modparam("proto_ws", "trace_on", 1)
...

trace_filter_route (string)

Define the name of a route in which you can filter which connections will be trace and which connections won’t be. In this route you will have information regarding source and destination ips and ports for the current connection. To disable tracing for a specific connection the last call in this route must be drop, any other exit mode resulting in tracing the current connection ( of course you still have to define a trace destination and trace must be on at the time this connection is opened.

Caution

Filtering on ip addresses and ports can be made using $si and $sp for matching either the entity that is connecting to OpenSIPS or the entity to which OpenSIPS is connecting. The name might be misleading ($si meaning the source ip if you read the docs) but in reality it is simply the socket other than the OpenSIPS socket. In order to match OpenSIPS interface (either the one that accepted the connection or the one that initiated a connection) $socket_in(ip) (ip) and $socket_in(port) (port) can be used.

Danger

If trace on is set to 0 or tracing is deactived via the mi command mi trace this route won’t be called.

Set trace_filter_route parameter

...
modparam("proto_ws", "trace_filter_route", "ws_filter")
...
/* all ws connections will go through this route if tracing is activated
 * and a trace destination is defined */
route[ws_filter] {
  ...
  /* all connections opened from/by ip 1.1.1.1:8000 will be traced
     on interface 1.1.1.10:5060(opensips listener)
     all the other connections won't be */
   if ( $si == "1.1.1.1" && $sp == 8000 &&
    $socket_in(ip) == "1.1.1.10"  && $socket_in(port) == 5060)
    exit;
  else
    drop;
}
...

require_origin (int)

Controls whether the module should require the Origin header or not.

Set require_origin parameter

...
modparam("proto_ws", "require_origin", no)
...

Exported MI Functions

ws_trace

Name: ws_trace

Parameters:

• trace_mode(optional): set ws tracing on and off. This parameter can be missing and the command will show the current tracing status for this module( on or off ); Possible values:
  • on
  • off

MI FIFO Command Format:

opensips-cli -x mi ws_trace on

Frequently Asked Questions

Q: Can OpenSIPS act as a WebSocket client?

Yes, starting with OpenSIPS 2.2, it can act as a WebSocket client.

Q: Does OpenSIPS support WebSocket message fragmentation?

No, WebSocket fragmentation mechanism is not supported.

Contributors

By Commit Statistics

Top contributors by DevScore⁽¹⁾, authored commits⁽²⁾ and lines added/removed⁽³⁾

#	Name	DevScore	Commits	Lines++	Lines—
1.	Razvan Crainea (@razvancrainea)	95	49	3920	733
2.	Ionut Ionita (@ionutrazvanionita)	21	14	592	112
3.	Bogdan-Andrei Iancu (@bogdan-iancu)	18	16	52	31
4.	Liviu Chircu (@liviuchircu)	14	11	80	82
5.	Stefan Darius (@dariusstefan)	11	5	380	84
6.	Vlad Patrascu (@rvlad-patrascu)	7	5	54	44
7.	Maksym Sobolyev (@sobomax)	7	5	20	20
8.	Vlad Paiu (@vladpaiu)	5	3	5	3
9.	Dan Shields	3	1	4	2
10.	Nick Altmann (@nikbyte)	3	1	2	2

All remaining contributors: James Stanley, Peter Lemenkov (@lemenkov), Julián Moreno Patiño.

(1) DevScore = author_commits + author_lines_added / (project_lines_added / project_commits) + author_lines_deleted / (project_lines_deleted / project_commits)

(2) including any documentation-related commits, excluding merge commits

(3) ignoring whitespace edits, renamed files and auto-generated files

By Commit Activity

#	Name	Commit Activity
1.	Stefan Darius (@dariusstefan)	Jun 2026 - Jul 2026
2.	Razvan Crainea (@razvancrainea)	Mar 2015 - Jun 2026
3.	Bogdan-Andrei Iancu (@bogdan-iancu)	Mar 2017 - Apr 2024
4.	Maksym Sobolyev (@sobomax)	Feb 2017 - Nov 2023
5.	Vlad Paiu (@vladpaiu)	Mar 2015 - Oct 2023
6.	James Stanley	Mar 2023 - Mar 2023
7.	Liviu Chircu (@liviuchircu)	Mar 2015 - Apr 2022
8.	Vlad Patrascu (@rvlad-patrascu)	May 2017 - Oct 2021
9.	Dan Shields	Aug 2021 - Aug 2021
10.	Nick Altmann (@nikbyte)	May 2021 - May 2021

All remaining contributors: Peter Lemenkov (@lemenkov), Ionut Ionita (@ionutrazvanionita), Julián Moreno Patiño.

(1) including any documentation-related commits, excluding merge commits

Documentation

Contributors

Last edited by: Razvan Crainea (@razvancrainea), Vlad Patrascu (@rvlad-patrascu), Bogdan-Andrei Iancu (@bogdan-iancu), Peter Lemenkov (@lemenkov), Liviu Chircu (@liviuchircu), Ionut Ionita (@ionutrazvanionita).

License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0