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tashian merged 1 commit into from
Oct 21, 2025
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Add OpenSSL to agent doc #442

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15 changes: 10 additions & 5 deletions platform/smallstep-agent.mdx
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
---
updated_at: October 01, 2025
updated_at: October 20, 2025
title: Smallstep Agent for Linux
html_title: Smallstep Agent for Device Management Guide
description: Deploy and configure Smallstep Agent on Linux. Automated device identity management and certificate renewal for enterprise Linux fleets.
Expand Down Expand Up @@ -236,11 +236,15 @@ If you get any errors, check the agent’s status:
sudo systemctl status step-agent.service
```

## **PKCS#11 Support**
### OpenSSL and PKCS#11 Support

The Smallstep agent provides a PKCS#11 server that can be used for a variety of integration use cases, such as NetworkManager and `wpa_supplicant` connections or web browser certificates. The PKCS#11 server is exposed as a UNIX socket at `$XDG_RUNTIME_DIR/step-agent/step-agent-pkcs11.sock`.
The Smallstep agent stores the certificate on the filesystem alongside a TPM TSS2-formatted file, which is a reference to a TPM-bound key. So, any software that integrates with OpenSSL's `tpm2-openssl` provider, or with the underlying `libtpm2-tss`, can use the TPM-bound key for TLS handshakes or other purposes.

### Example usage: Google Chrome
Because PKCS#11 is a common integration point, the Smallstep agent also provides a PKCS#11 server
for use with software like NetworkManager, `wpa_supplicant`, or web browsers.
The PKCS#11 server is exposed as a UNIX socket at `$XDG_RUNTIME_DIR/step-agent/step-agent-pkcs11.sock`.

#### Example usage: Google Chrome

For this example, we’re using Ubuntu 24.04. The location of `p11-kit-client.so` may vary.

Expand All @@ -260,7 +264,7 @@ In Chrome, you should now have access to certificates managed by Smallstep.

For regular usage, add `P11_KIT_SERVER_ADDRESS` to your environment more permanently. For example, you might add `P11_KIT_SERVER_ADDRESS=unix:path=$XDG_RUNTIME_DIR/step-agent/step-agent-pkcs11.sock` to your global `/etc/environment` file.

### Troubleshooting
#### Troubleshooting

The agent produces a log file or journal entries in systemd, depending on how it is installed and run.

Expand All @@ -272,3 +276,4 @@ pkcs11-tool --module /usr/lib/x86_64-linux-gnu/pkcs11/p11-kit-client.so \
```

See the [p11-kit](https://p11-glue.github.io/p11-glue/p11-kit/manual/) documentation for more details.