Set Up Service Registration Protocol (SRP) Server-Client Connectivity With OT CLI

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OpenThread offers both SRP server and client functionality, enabling devices to register DNS-based services using the standard DNS Update sent as unicast packets. This functionality enables DNS-Based Service Discovery.

This guide provides basic tasks that use some of the more common srp server and srp client commands.

SRP server commands

For a list of srp server commands, type help:

srp server help
addrmode
auto
disable
domain
enable
help
host
lease
seqnum
service
state
Done

SRP client commands

For a list of srp client commands, type help:

srp client help
autostart
callback
help
host
keyleaseinterval
leaseinterval
service
start
state
stop
ttl
Done

CLI Command Reference

For descriptions and syntax of all commands, refer to the CLI Command Reference. The SRP server commands begin alphabetically with srp server (enable,disable). The SRP client commands begin alphabetically with srp client autostart (get).

Thread Border Router codelab

The OpenThread Border Router codelab includes information about how to set up the SRP client end device.

Overviews of some basic SRP commands

SRP server and client commands can be used in sequence to perform typical SRP tasks:

Start the SRP server.

srp server enable enables the SRP server once you have created the Thread network.
Start the SRP client.
- srp client host name sets the host name to be used by the client.
- srp client host address (set) either enables auto host client address mode or explicitly sets the list of host client addresses.
- srp client service add adds a service with a given instance name, service name, and port number.
- srp client autostart enable enables auto-start mode. You can also manually start the client by running srp client start.
Verify the service status.
- srp client host and srp client service provide status about whether the client host and service have been successfully registered on the client node.
- srp server host and srp server service provide host and service status on the server node.
Remove the service.

srp client service remove removes a service but retains the service name.
Remove the host and service names.

srp client host remove removes the host and all registered services.

Examples of SRP server and client command usage

These examples use basic CLI commands to set up a Thread network, start the SRP server and client, verify server status, and remove a service. Sample data is used for illustrative purposes.

Start the SRP server

Start the SRP server node:
```
./output/simulation/bin/ot-cli-ftd 1
```

Set up a Thread network, then enable the SRP server by running the srp server enable command:

dataset init new
Done
dataset
Active Timestamp: 1
Channel: 22
Channel Mask: 0x07fff800
Ext PAN ID: 8d6ed7a05a28fb3b
Mesh Local Prefix: fded:5114:8263:1fe1::/64
Network Key: 7fcbae4153cc2955c28440c15d4d4219
Network Name: OpenThread-f7af
PAN ID: 0xf7af
PSKc: b658e40f174e3a11be149b302ef07a0f
Security Policy: 672, onrc
Done
dataset commit active
Done
ifconfig up
Done
thread start
Done
state
leader
Done
ipaddr
fded:5114:8263:1fe1:0:ff:fe00:fc00
fded:5114:8263:1fe1:0:ff:fe00:c000
fded:5114:8263:1fe1:68bc:ec03:c1ad:9325
fe80:0:0:0:a8cd:6e23:df3d:4193
Done
srp server enable
Done

Start the SRP client

Start the SRP Client node:
```
./output/simulation/bin/ot-cli-ftd 2
```

Join the Thread network, set the client host name and address, and register a service:

dataset networkkey 7fcbae4153cc2955c28440c15d4d4219
Done
dataset commit active
Done
ifconfig up
Done
thread start
Done
state
child
Done
ipaddr
fded:5114:8263:1fe1:0:ff:fe00:c001
fded:5114:8263:1fe1:44f9:cc06:4a2d:534
fe80:0:0:0:38dd:fdf7:5fd:24e
Done
srp client host name my-host
Done
srp client host address fded:5114:8263:1fe1:44f9:cc06:4a2d:534
Done
srp client service add my-service _ipps._tcp 12345
Done
srp client autostart enable
Done

As shown above, use the srp client autostart enable command to enable auto-start mode on the client. The client monitors network data to discover available SRP servers within the Thread network, then the client automatically starts itself.

If manually starting the client, run the following, and include the SRP address and port:
```
srp client start fded:5114:8263:1fe1:68bc:ec03:c1ad:9325 49154
Done
```
The SRP server listening UDP port is c002(49154) in the example above.

Verify the service status

Check if the host and service have been successfully registered on the client node:

srp client host
name:"my-host", state:Registered, addrs:[fded:5114:8263:1fe1:44f9:cc06:4a2d:534]
Done
srp client service
instance:"my-service", name:"_ipps._tcp", state:Registered, port:12345, priority:0, weight:0
Done

Make sure the output shows state:Registered for both host and service commands, as in the above example.

Check the host and service on the server node:

srp server host
my-host.default.service.arpa.
deleted: false 
addresses: [fded:5114:8263:1fe1:44f9:cc06:4a2d:534]
Done
srp server service
my-service._ipps._tcp.default.service.arpa.
deleted: false
port: 12345
priority: 0
weight: 0
ttl: 7200
lease: 7200
key-lease: 1209600
TXT: []
host: my-host.default.service.arpa.
addresses: [fded:5114:8263:1fe1:44f9:cc06:4a2d:534]
Done

Make sure the output shows deleted: false for both the srp server host and srp server service commands, as in the example above.

Remove the service

Remove the service via the client node:

srp client service remove my-service _ipps._tcp
Done

Confirm via the server node that the service has been removed:
```
srp server service
my-service._ipps._tcp.default.service.arpa.
deleted: true
Done
```
The service entry is listed in the output because the name of service is not removed.

Remove the host and service names

Remove the host and all its registered services:
```
srp client host remove 1
Done
```
Confirm on the server node that no host or service entries are listed:
```
srp server host
Done
srp server service
Done
>
```