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[ZT] Max SSH session duration #23402

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merged 5 commits into from
Jul 9, 2025
Merged

[ZT] Max SSH session duration #23402

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d801b92
max SSH session duration
ranbel Jul 2, 2025
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edit wording
ranbel Jul 2, 2025
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edit paragraph spacing
ranbel Jul 2, 2025
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replce controlpersist with channeltimeout
ranbel Jul 8, 2025
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edit wording
ranbel Jul 8, 2025
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6 changes: 6 additions & 0 deletions ...re-one/connections/connect-networks/use-cases/ssh/ssh-infrastructure-access.mdx
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Expand Up @@ -155,10 +155,16 @@ To set up the Logpush job, refer to [Logpush integration](/cloudflare-one/insigh

## Known limitations

### SSH features

The following SSH features are not supported:

- `sftp` commands
- `scp` commands that utilize OpenSSH versions > 9.0, because OpenSSH 9.0+ leverages `sftp` to execute the command
- Local and remote port forwarding
- SSH agent forwarding
- X11 forwarding

### Session duration

SSH sessions have a maximum expected duration of 10 hours. For more information, refer to the [Troubleshooting FAQ](/cloudflare-one/faq/troubleshooting/#long-lived-ssh-sessions-frequently-disconnect).
12 changes: 12 additions & 0 deletions src/content/docs/cloudflare-one/faq/troubleshooting.mdx
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Expand Up @@ -374,3 +374,15 @@ Get-ChildItem -Path "HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP" -Recurse
## I get an `Invalid session. Please try logging in again.` error from Access when trying to log in to the Cloudflare dashboard via SSO.

Cloudflare Access uses a [`CF_Session` cookie](/cloudflare-one/identity/authorization-cookie/#access-cookies) to validate that the same browser both initiated and completed your sign-in. The `Invalid session` error means Access was unable to validate this cookie. Ensure that there is no software or firewall on your device or network that may be interfering with requests to Access.

## Long-lived SSH sessions frequently disconnect.

All connections proxied through Cloudflare Gateway, including traffic to [Access for Infrastructure](/cloudflare-one/connections/connect-networks/use-cases/ssh/ssh-infrastructure-access/) SSH targets, have a maximum guaranteed duration of 10 hours. It is possible for connections to last longer than 10 hours. However, if a connection is active at the time of a Gateway release, Gateway will terminate the connection 10 hours later. Releases are not scheduled and can occur multiple times a week.

To prevent long-lived SSH connections from breaking unexpectedly, we recommend terminating sessions on a predefined schedule. For example, you could set an 8-hour idle timeout so that inactive sessions automatically disconnect during off hours. To configure an idle timeout, add the `ChannelTimeout` option to either the SSH server (`/etc/ssh/sshd_config`) or client configuration file (`~/.ssh/config`):

```txt
ChannelTimeout global=8h
```

Implementing [`ChannelTimeout` on the client side](https://man.openbsd.org/ssh_config#ChannelTimeout) allows users to choose a time that works for them, whereas implementing it on the [server side](https://man.openbsd.org/sshd_config#ChannelTimeout) removes the configuration burden from the end user.
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