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Teleport
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 containcurl 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.
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 version 16.2.1 or above. If you want to get started with Teleport, sign up for a free trial or set up a demo environment.
-
The
tctl
admin tool andtsh
client tool.Visit Installation for instructions on downloading
tctl
andtsh
.
-
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 -r5.8.17
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 Session Recording for more details.
Linux distributions and supported kernels
Teleport supports enhanced session recording with BPF on amd64
and arm64
architectures.
Distro name | Distro version | Kernel Version |
---|---|---|
Ubuntu "Groovy Gorilla" | 20.10 | 5.8+ |
Fedora | 33 | 5.8+ |
Arch Linux | 2020.09.01 | 5.8.5+ |
Flatcar | 2765.2.2 | 5.10.25+ |
Amazon Linux | 2 | 5.10+ |
- To check that you can connect to your Teleport cluster, sign in with
tsh login
, then verify that you can runtctl
commands using your current credentials. For example:If you can connect to the cluster and run thetsh login --proxy=teleport.example.com --user=[email protected]tctl statusCluster teleport.example.com
Version 16.2.1
CA pin sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678
tctl status
command, you can use your current credentials to run subsequenttctl
commands from your workstation. If you host your own Teleport cluster, you can also runtctl
commands on the computer that hosts the Teleport Auth Service for full permissions.
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.
Install Teleport on your Linux server:
-
Assign edition to one of the following, depending on your Teleport edition:
Edition Value Teleport Enterprise Cloud cloud
Teleport Enterprise (Self-Hosted) enterprise
Teleport Community Edition oss
-
Get the version of Teleport to install. If you have automatic agent updates enabled in your cluster, query the latest Teleport version that is compatible with the updater:
TELEPORT_DOMAIN=example.teleport.comTELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/automaticupgrades/channel/default/version | sed 's/v//')"Otherwise, get the version of your Teleport cluster:
TELEPORT_DOMAIN=example.teleport.comTELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/ping | jq -r '.server_version')" -
Install Teleport on your Linux server:
curl https://cdn.teleport.dev/install-v16.2.1.sh | bash -s ${TELEPORT_VERSION} editionThe installation script detects the package manager on your Linux server and uses it to install Teleport binaries. To customize your installation, learn about the Teleport package repositories in the installation guide.
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=nodeThe invite token: abcd123-insecure-do-not-use-this
You can also list all generated non-expired tokens:
tctl tokens lsToken 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
# Optional: Controls the path inside cgroupv2 hierarchy where Teleport
# cgroups will be placed. Default value: /teleport
root_path: /teleport
If you operate multiple Teleport instances on the same system, customize the
root_path
configuration to change the base cgroupv2 slice path for session
system resources. This ensures security isolation between sessions from
different Teleport instances, allowing you to apply distinct security rules and
resource controls.
Start Teleport on your Node
Configure the Teleport SSH Service to start automatically when the host boots up by creating a systemd service for it. The instructions depend on how you installed the Teleport SSH Service.
On the host where you will run the Teleport SSH Service, enable and start Teleport:
sudo systemctl enable teleportsudo systemctl start teleport
On the host where you will run the Teleport SSH Service, create a systemd service configuration for Teleport, enable the Teleport service, and start Teleport:
sudo teleport install systemd -o /etc/systemd/system/teleport.servicesudo systemctl enable teleportsudo systemctl start teleport
You can check the status of the Teleport SSH Service with systemctl status teleport
and view its logs with journalctl -fu teleport
.
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.
Each command run will generate a session.command
event, similar to
the following:
{
"argv": [
"https://wttr.in"
],
"cgroup_id": 2360,
"cluster_name": "purple",
"code": "T4000I",
"ei": 50,
"event": "session.command",
"login": "ec2-user",
"namespace": "default",
"path": "/bin/curl",
"pid": 5007,
"ppid": 4985,
"program": "curl",
"return_code": 0,
"server_hostname": "ip-172-31-34-128.us-east-2.compute.internal",
"server_id": "531dc1de-c2c9-49bd-a0e3-4f4f3a523f5f",
"sid": "86aca627-971d-4883-854d-d309ba04c658",
"time": "2023-07-04T16:42:20.54Z",
"uid": "9b825e22-744d-4130-94c5-dea49198ae3d",
"user": "[email protected]"
}
Network connections will be logged as session.network
events, similar to the following:
{
"action": 0,
"cgroup_id": 2360,
"cluster_name": "purple",
"code": "T4002I",
"dst_addr": "5.9.243.187",
"dst_port": 443,
"ei": 51,
"event": "session.network",
"login": "ec2-user",
"namespace": "default",
"operation": 0,
"pid": 5007,
"program": "curl",
"server_hostname": "ip-172-31-34-128.us-east-2.compute.internal",
"server_id": "531dc1de-c2c9-49bd-a0e3-4f4f3a523f5f",
"sid": "86aca627-971d-4883-854d-d309ba04c658",
"src_addr": "172.31.34.128",
"time": "2023-07-04T16:42:20.55Z",
"uid": "da151350-bf45-4a04-a62b-7a4fc805e744",
"user": "[email protected]",
"version": 4
}
When Enhanced Session Recording is enabled, the session.end
event emitted when a session
ends will also include the "enhanced_recording": true
field, similar to the following:
{
"code": "T2004I",
"ei": 23,
"enhanced_recording": true,
"event": "session.end",
"interactive": true,
"namespace": "default",
"participants": [
"[email protected]"
],
"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": "[email protected]"
}
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.
Enhanced session recording events will be shown in Teleport's audit log, which you can inspect by visiting Teleport's Web UI.
Each command run will generate a session.command
event, similar to
the following:
{
"argv": [
"https://wttr.in"
],
"cgroup_id": 2360,
"cluster_name": "purple",
"code": "T4000I",
"ei": 50,
"event": "session.command",
"login": "ec2-user",
"namespace": "default",
"path": "/bin/curl",
"pid": 5007,
"ppid": 4985,
"program": "curl",
"return_code": 0,
"server_hostname": "ip-172-31-34-128.us-east-2.compute.internal",
"server_id": "531dc1de-c2c9-49bd-a0e3-4f4f3a523f5f",
"sid": "86aca627-971d-4883-854d-d309ba04c658",
"time": "2023-07-04T16:42:20.54Z",
"uid": "9b825e22-744d-4130-94c5-dea49198ae3d",
"user": "[email protected]"
}
Network connections will be logged as session.network
events, similar to the following:
{
"action": 0,
"cgroup_id": 2360,
"cluster_name": "purple",
"code": "T4002I",
"dst_addr": "5.9.243.187",
"dst_port": 443,
"ei": 51,
"event": "session.network",
"login": "ec2-user",
"namespace": "default",
"operation": 0,
"pid": 5007,
"program": "curl",
"server_hostname": "ip-172-31-34-128.us-east-2.compute.internal",
"server_id": "531dc1de-c2c9-49bd-a0e3-4f4f3a523f5f",
"sid": "86aca627-971d-4883-854d-d309ba04c658",
"src_addr": "172.31.34.128",
"time": "2023-07-04T16:42:20.55Z",
"uid": "da151350-bf45-4a04-a62b-7a4fc805e744",
"user": "[email protected]",
"version": 4
}
When Enhanced Session Recording is enabled, the session.end
event emitted when a session
ends will also include the "enhanced_recording": true
field, similar to the following:
{
"code": "T2004I",
"ei": 23,
"enhanced_recording": true,
"event": "session.end",
"interactive": true,
"namespace": "default",
"participants": [
"[email protected]"
],
"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": "[email protected]"
}
Next steps
- Read more about session recording.
- See all configuration options for Enhanced Session Recording in our Configuration Reference.