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Enhanced Session Recording with BPF

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Enhanced SSH Session Recording with BPF

Length: 05:01

This guide explains Enhanced Session Recording for SSH with BPF and how to set it up in your Teleport cluster.

Teleport's default SSH and Kubernetes session recording feature captures what is echoed to a terminal.

This has inherent advantages. For example, because no input is captured, Teleport session recordings typically do not contain passwords that were entered into a terminal.

The disadvantage is that there are several techniques for rendering session recordings less useful:

Obfuscation. For example, even though the command echo Y3VybCBodHRwOi8vd3d3LmV4YW1wbGUuY29tCg== | base64 --decode | sh does not contain curl http://www.example.com, when decoded, that is what is run.
Shell scripts. For example, if a user uploads and executes a script, the commands run within the script are not captured, only the output.
Terminal controls. Terminals support a wide variety of controls including the ability for users to disable terminal echo. This is frequently used when requesting credentials. Disabling terminal echo allows commands to be run without being captured.

Furthermore, due to their unstructured nature, session recordings are difficult to ingest and perform monitoring and alerting on.

Teleport Enhanced Session Recording mitigates all three concerns by providing advanced security and greater logging capabilities, and better correlates a user with their activities.

Security Warning

Teleport Enhanced Session Recording does not provide a secure environment on its own and is not a substitute for a Linux Security Module (SELinux, AppArmor, etc.). It must be paired with reasonable system hardening practices to enforce a trusted host environment, including proper access control on core system binaries and libraries and well-designed user management.

Note that privileged users (either as root or via sudo) can interfere with session recording activities (such as unloading/disabling the necessary libraries, altering how Teleport is run, tampering with kernel functionality, creating tunnels, or just performing actions outside of the restricted session). Also, a local user with both monitored and unmonitored console sessions or ptrace privileges may not be fully captured in recordings.

Commands executed via daemons (systemd, crond, atd, etc.) could be outside of the recorded session scope. Proper network-based restrictions for ingress traffic must also be implemented to prevent possible unauthorized data transfer.

Additionally, certain forensic information such as full binary paths (accounting for any potential symbolic links), any modifications via shared library preloading, and environment variables may not be captured in session recordings.

Prerequisites

A running Teleport cluster. For details on how to set this up, see one of our Getting Started guides.
The tctl admin tool and tsh client tool version >= 13.0.3.
```
tctl version
Teleport v13.0.3 go1.20
tsh version
Teleport v13.0.3 go1.20
```
See Installation for details.

A running Teleport Enterprise cluster. For details on how to set this up, see our Enterprise Getting Started guide.
The Enterprise tctl admin tool and tsh client tool version >= 13.0.3, which you can download by visiting your Teleport account.
```
tctl version
Teleport Enterprise v13.0.3 go1.20
tsh version
Teleport v13.0.3 go1.20
```

Cloud is not available for Teleport v.
Please use the latest version of Teleport Enterprise documentation.

At least one host that you will use to run the Teleport Node Service. The host must run Linux kernel 5.8 (or above).

You can check your kernel version using the uname command. The output should look something like the following.
```
uname -r
5.8.17
```
See below for more details on the required versions for your Linux kernel and distribution.

Our Standard Session Recording works with older Linux kernels. View Teleport Nodes for more details.

Linux distributions and supported kernels

Distro name	Distro version	Kernel Version
Ubuntu "Groovy Gorilla"	20.10	5.8+
Fedora	33	5.8+
Archlinux	2020.09.01	5.8.5+
Flatcar	2765.2.2	5.10.25+
Amazon Linux	2	5.10+

Make sure you can connect to Teleport. Log in to your cluster using tsh, then use tctl remotely:
```
tsh login --proxy=teleport.example.com [email protected]
tctl status
Cluster  teleport.example.com
Version  13.0.3
CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678
```
You can run subsequent tctl commands in this guide on your local machine.
For full privileges, you can also run tctl commands on your Auth Service host.

Step 1/2. Configure a Teleport Node

Install Teleport on your Node

On the host where you will run your Teleport Node, follow the instructions for your environment to install Teleport.

Use the appropriate commands for your environment to install your package.

Teleport Edition

Download Teleport's PGP public key
sudo curl https://apt.releases.teleport.dev/gpg \-o /usr/share/keyrings/teleport-archive-keyring.asc
Source variables about OS version
source /etc/os-release
Add the Teleport APT repository for v13. You'll need to update this
file for each major release of Teleport.
echo "deb [signed-by=/usr/share/keyrings/teleport-archive-keyring.asc] \https://apt.releases.teleport.dev/${ID?} ${VERSION_CODENAME?} stable/v13" \| sudo tee /etc/apt/sources.list.d/teleport.list > /dev/null
sudo apt-get update
sudo apt-get install teleport

Source variables about OS version
source /etc/os-release
Add the Teleport YUM repository for v13. You'll need to update this
file for each major release of Teleport.
sudo yum-config-manager --add-repo "$(rpm --eval "https://yum.releases.teleport.dev/$ID/$VERSION_ID/Teleport/%{_arch}/stable/v13/teleport.repo")"
sudo yum install teleport
Tip: Add /usr/local/bin to path used by sudo (so 'sudo tctl users add' will work as per the docs)
echo "Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin" > /etc/sudoers.d/secure_path

Source variables about OS version
source /etc/os-release
Add the Teleport YUM repository for v13. You'll need to update this
file for each major release of Teleport.
Use the dnf config manager plugin to add the teleport RPM repo
sudo dnf config-manager --add-repo "$(rpm --eval "https://yum.releases.teleport.dev/$ID/$VERSION_ID/Teleport/%{_arch}/stable/v13/teleport.repo")"
Install teleport
sudo dnf install teleport
Tip: Add /usr/local/bin to path used by sudo (so 'sudo tctl users add' will work as per the docs)
echo "Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin" > /etc/sudoers.d/secure_path

In the example commands below, update $SYSTEM_ARCH with the appropriate value (amd64, arm64, or arm). All example commands using this variable will update after one is filled out.

curl https://get.gravitational.com/teleport-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
shasum -a 256 teleport-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
cd teleport
sudo ./install

Download Teleport's PGP public key
sudo curl https://apt.releases.teleport.dev/gpg \-o /usr/share/keyrings/teleport-archive-keyring.asc
Source variables about OS version
source /etc/os-release
Add the Teleport APT repository for v13. You'll need to update this
file for each major release of Teleport.
echo "deb [signed-by=/usr/share/keyrings/teleport-archive-keyring.asc] \https://apt.releases.teleport.dev/${ID?} ${VERSION_CODENAME?} stable/v13" \| sudo tee /etc/apt/sources.list.d/teleport.list > /dev/null
sudo apt-get update
sudo apt-get install teleport-ent

For FedRAMP/FIPS-compliant installations, install the teleport-ent-fips package instead:

sudo apt-get install teleport-ent-fips

Source variables about OS version
source /etc/os-release
Add the Teleport YUM repository for v13. You'll need to update this
file for each major release of Teleport.
sudo yum-config-manager --add-repo "$(rpm --eval "https://yum.releases.teleport.dev/$ID/$VERSION_ID/Teleport/%{_arch}/stable/v13/teleport.repo")"
sudo yum install teleport-ent
Tip: Add /usr/local/bin to path used by sudo (so 'sudo tctl users add' will work as per the docs)
echo "Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin" > /etc/sudoers.d/secure_path

For FedRAMP/FIPS-compliant installations, install the teleport-ent-fips package instead:

sudo yum install teleport-ent-fips

Source variables about OS version
source /etc/os-release
Add the Teleport YUM repository for v13. You'll need to update this
file for each major release of Teleport.
Use the dnf config manager plugin to add the teleport RPM repo
sudo dnf config-manager --add-repo "$(rpm --eval "https://yum.releases.teleport.dev/$ID/$VERSION_ID/Teleport/%{_arch}/stable/v13/teleport.repo")"
Install teleport
sudo dnf install teleport-ent
Tip: Add /usr/local/bin to path used by sudo (so 'sudo tctl users add' will work as per the docs)
echo "Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin" > /etc/sudoers.d/secure_path

For FedRAMP/FIPS-compliant installations, install the teleport-ent-fips package instead:

sudo dnf install teleport-ent-fips

In the example commands below, update $SYSTEM_ARCH with the appropriate value (amd64, arm64, or arm). All example commands using this variable will update after one is filled out.

curl https://get.gravitational.com/teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
shasum -a 256 teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-bin.tar.gz
cd teleport-ent
sudo ./install

For FedRAMP/FIPS-compliant installations of Teleport Enterprise, package URLs will be slightly different:

curl https://get.gravitational.com/teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-fips-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-fips-bin.tar.gz
shasum -a 256 teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-fips-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-ent-v13.0.3-linux-$SYSTEM_ARCH-fips-bin.tar.gz
cd teleport-ent
sudo ./install

Cloud is not available for Teleport v.
Please use the latest version of Teleport Enterprise documentation.

Generate a token

Use the tctl tool to generate an invite token that your Node will use to join the cluster. In the following example, a new token is created with a TTL of five minutes:

Generate a short-lived invitation token for a new node:
tctl nodes add --ttl=5m --roles=node
The invite token: abcd123-insecure-do-not-use-this
You can also list all generated non-expired tokens:
tctl tokens ls
Token                            Type            Expiry Time
------------------------         -----------     ---------------
abcd123-insecure-do-not-use-this         Node            25 Sep 18 00:21 UTC
... or revoke an invitation token before it's used:
tctl tokens rm abcd123-insecure-do-not-use-this

Create a configuration file

Set up your Teleport Node with the following content in /etc/teleport.yaml.

# Example config to be saved as etc/teleport.yaml
version: v3
teleport:
  nodename: graviton-node
  # The token you created earlier
  auth_token: abcd123-insecure-do-not-use-this

  # Replace with the address of the Teleport Auth Service
  auth_server: 127.0.0.1:3025
  # Or specify the Proxy Service address.
  proxy_server: 127.0.0.1:3080

  data_dir: /var/lib/teleport
proxy_service:
  enabled: false
auth_service:
  enabled: false
ssh_service:
  enabled: true
  enhanced_recording:
    # Enable or disable enhanced auditing for this node. Default value: false.
    enabled: true

    # Optional: command_buffer_size is optional with a default value of 8 pages.
    command_buffer_size: 8

    # Optional: disk_buffer_size is optional with default value of 128 pages.
    disk_buffer_size: 128

    # Optional: network_buffer_size is optional with default value of 8 pages.
    network_buffer_size: 8

    # Optional: Controls where cgroupv2 hierarchy is mounted. Default value:
    # /cgroup2.
    cgroup_path: /cgroup2

Start Teleport on your Node

teleport start

Step 2/2. Inspect the audit log

Enhanced session recording events will be shown in Teleport's audit log, which you can inspect by visiting Teleport's Web UI.

Events emitted via Enhanced Session Recording will include the "enhanced_recording": true field in events similar to the following:

{
  "code": "T2004I",
  "ei": 23,
  "enhanced_recording": true,
  "event": "session.end",
  "interactive": true,
  "namespace": "default",
  "participants": [
    "benarent"
  ],
  "server_id": "585fc225-5cf9-4e9f-8ff6-1b0fd6885b09",
  "sid": "ca82b98d-1d30-11ea-8244-cafde5327a6c",
  "time": "2019-12-12T22:44:46.218Z",
  "uid": "83e67464-a93a-4c7c-8ce6-5a3d8802c3b2",
  "user": "benarent"
}

If your Teleport cluster uses a file-based event log, you can examine your audit log on the Teleport Auth Service host.

Teleport's session recordings backend is configured via the teleport.storage.audit_sessions_uri field. If a provided URI includes a scheme that belongs to a cloud-based service (e.g., s3:// or dynamodb://), you will not be able to inspect session recordings in the filesystem of your Auth Service host.

Examine the contents of /var/lib/teleport/log as shown below:

teleport-auth ~:  tree /var/lib/teleport/log
/var/lib/teleport/log
├── 1048a649-8f3f-4431-9529-0c53339b65a5
│   ├── 2020-01-13.00:00:00.log
│   └── sessions
│       └── default
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.chunks.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.events.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.session.command-events.gz
│           ├── fad07202-35bb-11ea-83aa-125400432324-0.session.network-events.gz
│           └── fad07202-35bb-11ea-83aa-125400432324.index
├── events.log -> /var/lib/teleport/log/1048a649-8f3f-4431-9529-0c53339b65a5/2020-01-13.00:00:00.log
├── playbacks
│   └── sessions
│       └── default
└── upload
└── sessions
└── default

To quickly check the status of the audit log, you can simply tail the logs with tail -f /var/lib/teleport/log/events.log. The resulting capture from Teleport will be a JSON log for each command and network request.

Cloud is not available for Teleport v.
Please use the latest version of Teleport Enterprise documentation.

Next steps

Read more about session recording.
See all configuration options for Enhanced Session Recording in our Configuration Reference.

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