# JSON-RPC Interface The headless daemon `canuckcoind` has the JSON-RPC API enabled by default, the GUI `canuckcoin-qt` has it disabled by default. This can be changed with the `-server` option. In the GUI it is possible to execute RPC methods in the Debug Console Dialog. ## Versioning The RPC interface might change from one major version of Canuckcoin Core to the next. This makes the RPC interface implicitly versioned on the major version. The version tuple can be retrieved by e.g. the `getnetworkinfo` RPC in `version`. Usually deprecated features can be re-enabled during the grace-period of one major version via the `-deprecatedrpc=` command line option. The release notes of a new major release come with detailed instructions on what RPC features were deprecated and how to re-enable them temporarily. ## Security The RPC interface allows other programs to control Canuckcoin Core, including the ability to spend funds from your wallets, affect consensus verification, read private data, and otherwise perform operations that can cause loss of money, data, or privacy. This section suggests how you should use and configure Canuckcoin Core to reduce the risk that its RPC interface will be abused. - **Securing the executable:** Anyone with physical or remote access to the computer, container, or virtual machine running Canuckcoin Core can compromise either the whole program or just the RPC interface. This includes being able to record any passphrases you enter for unlocking your encrypted wallets or changing settings so that your Canuckcoin Core program tells you that certain transactions have multiple confirmations even when they aren't part of the best block chain. For this reason, you should not use Canuckcoin Core for security sensitive operations on systems you do not exclusively control, such as shared computers or virtual private servers. - **Securing local network access:** By default, the RPC interface can only be accessed by a client running on the same computer and only after the client provides a valid authentication credential (username and passphrase). Any program on your computer with access to the file system and local network can obtain this level of access. Additionally, other programs on your computer can attempt to provide an RPC interface on the same port as used by Canuckcoin Core in order to trick you into revealing your authentication credentials. For this reason, it is important to only use Canuckcoin Core for security-sensitive operations on a computer whose other programs you trust. - **Securing remote network access:** You may optionally allow other computers to remotely control Canuckcoin Core by setting the `rpcallowip` and `rpcbind` configuration parameters. These settings are only meant for enabling connections over secure private networks or connections that have been otherwise secured (e.g. using a VPN or port forwarding with SSH or stunnel). **Do not enable RPC connections over the public Internet.** Although Canuckcoin Core's RPC interface does use authentication, it does not use encryption, so your login credentials are sent as clear text that can be read by anyone on your network path. Additionally, the RPC interface has not been hardened to withstand arbitrary Internet traffic, so changing the above settings to expose it to the Internet (even using something like a Tor hidden service) could expose you to unconsidered vulnerabilities. See `canuckcoind -help` for more information about these settings and other settings described in this document. Related, if you use Canuckcoin Core inside a Docker container, you may need to expose the RPC port to the host system. The default way to do this in Docker also exposes the port to the public Internet. Instead, expose it only on the host system's localhost, for example: `-p 127.0.0.1:9332:9332` - **Secure authentication:** By default, Canuckcoin Core generates unique login credentials each time it restarts and puts them into a file readable only by the user that started Canuckcoin Core, allowing any of that user's RPC clients with read access to the file to login automatically. The file is `.cookie` in the Canuckcoin Core configuration directory, and using these credentials is the preferred RPC authentication method. If you need to generate static login credentials for your programs, you can use the script in the `share/rpcauth` directory in the Canuckcoin Core source tree. As a final fallback, you can directly use manually-chosen `rpcuser` and `rpcpassword` configuration parameters---but you must ensure that you choose a strong and unique passphrase (and still don't use insecure networks, as mentioned above). - **Secure string handling:** The RPC interface does not guarantee any escaping of data beyond what's necessary to encode it as JSON, although it does usually provide serialized data using a hex representation of the bytes. If you use RPC data in your programs or provide its data to other programs, you must ensure any problem strings are properly escaped. For example, multiple websites have been manipulated because they displayed decoded hex strings that included HTML `