> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-3a82795f.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
> Documentation for the SSH interface in ClickHouse
# SSH interface with PTY
export const CloudNotSupportedBadge = () => {
return
ClickHouse server allows to connect to itself directly using the SSH protocol. Any client is allowed.
After creating a [database user identified by an SSH key](/resources/support-center/knowledge-base/cloud-services/how-to-connect-to-ch-cloud-using-ssh-keys):
```sql theme={null}
CREATE USER abcuser IDENTIFIED WITH ssh_key BY KEY '' TYPE 'ssh-ed25519';
```
You're able to use this key to connect to a ClickHouse server. It will open a pseudoterminal (PTY) with an interactive session of clickhouse-client.
```bash theme={null}
> ssh -i ~/test_ssh/id_ed25519 abcuser@localhost -p 9022
ClickHouse embedded version 25.1.1.1.
ip-10-1-13-116.us-west-2.compute.internal :) SELECT 1;
SELECT 1
Query id: cdd91b7f-215b-4537-b7df-86d19bf63f64
┌─1─┐
1. │ 1 │
└───┘
1 row in set. Elapsed: 0.002 sec.
```
The command execution over SSH (the non-interactive mode) is also supported:
```bash theme={null}
> ssh -i ~/test_ssh/id_ed25519 abcuser@localhost -p 9022 "select 1"
1
```
Server configuration
In order to enable the SSH server capability, you need to uncomment or place the following section in your `config.xml`:
```xml theme={null}
9022path-to-the-key
```
The host key is an integral part of a SSH protocol. The public part of this key is stored in the `~/.ssh/known_hosts` file on the client side and typically needed to prevent man-in-the-middle type of attacks. When connecting to the server for the first time you will see the message below:
```shell theme={null}
The authenticity of host '[localhost]:9022 ([127.0.0.1]:9022)' can't be established.
RSA key fingerprint is SHA256:3qxVlJKMr/PEKw/hfeg06HAK451Tt0eenhwqQvh58Do.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])?
```
This, in fact means: "Do you want to remember the public key of this host and continue connecting?".
You can tell your SSH client not to verify the host by passing an option:
```bash theme={null}
ssh -o "StrictHostKeyChecking no" user@host
```
Configuring embedded client
You're able to pass options to an embedded client similar to the ordinary `clickhouse-client`, but with a few limitations.
Since this is an SSH protocol, the only way to pass parameters to the target host is through environment variables.
For example setting the `format` can be done this way:
```bash theme={null}
> ssh -o SetEnv="format=Pretty" -i ~/test_ssh/id_ed25519 abcuser@localhost -p 9022 "SELECT 1"
┏━━━┓
┃ 1 ┃
┡━━━┩
1. │ 1 │
└───┘
```
You're able to change any user-level setting this way and additionally pass most of the ordinary `clickhouse-client` options (except ones which don't make sense in this setup.)
Important:
In case if both `query` option and the SSH command is passed, the latter one is added to the list of queries to execute:
```bash theme={null}
ubuntu ip-10-1-13-116@~$ ssh -o SetEnv="format=Pretty query=\"SELECT 2;\"" -i ~/test_ssh/id_ed25519 abcuser@localhost -p 9022 "SELECT 1"
┏━━━┓
┃ 2 ┃
┡━━━┩
1. │ 2 │
└───┘
┏━━━┓
┃ 1 ┃
┡━━━┩
1. │ 1 │
└───┘
```