# SSH rate limits

Source: https://docs.fortrabbit.com/platform/code-access/ssh-rate-limits
Published: 2026-10-23
Updated: 2026-10-23
Reviewed: 2026-10-23

> fortrabbit limits SSH connections per IP address. The thresholds, the error each limit shows, and how to get unblocked.


## About SSH rate limits

The SSH endpoint limits connections per IP address, to block brute-force logins and runaway clients:

| Per IP address         | Slowed down | Rejected | Dropped |
| ---------------------- | ----------: | -------: | ------: |
| Concurrent connections |   above 20  | above 40 | above 80 |
| New connections a minute | above 20  | above 100 | above 200 |

Repeated logins with a wrong key also block the address for a while. The cause is often a program in the background, such as a database GUI that opens a new tunnel per tab, or an SFTP plugin in the IDE.

The limits lift a few minutes after the traffic stops. A client stuck in a loop keeps the address blocked until it is stopped. fortrabbit does not allowlist customer IP addresses.

## Identify a rate limit

A rate limit is likely when the same connection worked before, and unlikely when SSH never worked. To check, connect from another network, for example through a phone hotspot, or read the output of the `ssh` command line client.

### Too many connections

The server answers with a banner instead of an SSH greeting:



```shell
$ ssh {{app-env-id}}@ssh.{{region}}.frbit.app
Bad remote protocol version identification: 'SSH-Restricted_TooManyConcurrentConnections'
banner exchange: Connection to X.X.X.X port 22: invalid format
```

With `-v`, the banner shows the reason and the numbers:



```shell
$ ssh {{app-env-id}}@ssh.{{region}}.frbit.app -v
...
debug1: Local version string SSH-2.0-OpenSSH_10.0
debug1: kex_exchange_identification: banner line 0:
debug1: kex_exchange_identification: banner line 1: ******************************************************
debug1: kex_exchange_identification: banner line 2:        SSH connection rejected due to overusage!
debug1: kex_exchange_identification: banner line 3:
debug1: kex_exchange_identification: banner line 4:   Reason:    TooManyConcurrentConnections
debug1: kex_exchange_identification: banner line 5:   Active:    41 concurrent connections (limit: 40)
debug1: kex_exchange_identification: banner line 6:   Rate:      10 connections per minute (limit: 100)
debug1: kex_exchange_identification: banner line 7:   Client IP: Y.Y.Y.Y
debug1: kex_exchange_identification: banner line 8: ******************************************************
debug1: kex_exchange_identification: banner line 9:
Bad remote protocol version identification: 'SSH-Restricted_TooManyConcurrentConnections'
banner exchange: Connection to X.X.X.X port 22: invalid format
```

The block lifts once the connections drop below the limits.

### Connection closed

The server closes the connection right away, without a banner. The address is blocked after too many failed logins.



```
$ ssh {{app-env-id}}@ssh.{{region}}.frbit.app
Connection closed by X.X.X.X port 22
```

Stop all connection attempts for a few minutes, and the block lifts.

### Permission denied

The address is not blocked, but the key is wrong. Check the [SSH keys](/platform/code-access/troubleshooting#ssh-key-setup):



```
$ ssh {{app-env-id}}@ssh.{{region}}.frbit.app
Permission denied (publickey).
```

---

- [Code access troubleshooting](/platform/code-access/troubleshooting)