Network flow logs

Network flow logs let you understand how and when nodes on your Tailscale network (known as a tailnet) connect to each other. You can export network logs for long-term storage, security analysis, threat detection, or incident investigation. You can also stream logs to a security information and event management (SIEM) system.

The data captured in network logs is the flow of network traffic, not the contents of network traffic. Tailscale does not and cannot inspect your traffic. For more information about how your data stays private, refer to our Security page.

Network flow logs are available for the most recent 30 days.

This feature is available for the Premium and Enterprise plans.

Only nodes using Tailscale v1.34 or later can send networking telemetry to the Tailscale logs service.

How it works

When network flow logs are enabled (and not using --no-logs-no-support), nodes report their flow information (for both ends of the connection) to the Tailscale logs service. A connection can be between:

Two nodes
A node and a device behind a subnet router
A node and a public device accessed through an exit node

When the connection is between a node and a device behind a subnet router, the subnet router logs the connection. When the connection is between a node and a public device accessed through an exit node, the exit node logs the connection.

Logs occur between transferred and received network connections, and entries exist for both ends.

Logs occur at two layers: the virtual layer and the physical layer. The virtual layer is the Tailscale network (often with IP addresses in 100.x.x.x) that Tailscale provides for each device. The physical layer involves all the physical network interfaces on a device. When one node transmits a packet to another, the packet must cross through the physical layer. The summation of all traffic routed at the virtual layer is generally equal to the traffic routed at the physical layer.

Tailscale centrally stores network logs and lets you export them. Tailscale does not log the actual contents or data of the network traffic.

Network logs structure

Network logs contain an array of messages that provide details about network flow activity. Each message contains the following components:

nodeId: The node that generated this log message. It is a globally unique identifier of a node. It is not the same value as the node name. If you want to map nodeId to a node name, you can use the /api/v2/device/:nodeId method and examine the name field.
logged: The time in UTC that the Tailscale logs service recorded the message. Generally, the logged time is after the end time within a message.
start: The start time in UTC for the network traffic flow data in the message, as recorded by the node that generated the message.
end: The end time in UTC for the network traffic flow data in the message, as recorded by the node that generated the message.
virtualTraffic: Counters for the network flow's virtual traffic. Virtual traffic is traffic that occurs between nodes in your tailnet.
subnetTraffic: Counters for the network flow's traffic routed through an advertised subnet router.
exitTraffic: Counters for the network flow's traffic routed through an exit node. For traffic from a node to a public device through an exit node, the source will be the Tailscale IP address, but the protocol, source port, and destination will be empty. For traffic responses from a public device to a node through an exit node, the destination will be the Tailscale IP address, but the protocol, destination port, and source will be empty. Tailscale doesn't gather detailed information about individual connections to preserve privacy.
physicalTraffic: Counters for the network flow's traffic on the physical network layer that operates below the virtual Tailscale network. Traffic information at the physical layer is gathered at a slightly different time than the virtual layer, so packets flowing through the virtual layer may not exactly line up with those at the physical layer.
exitTraffic: Counters for the network flow's traffic routed through an exit node. For traffic from a node to a public device through an exit node, the source is the Tailscale IP address, but the protocol, source port, and destination are empty. For traffic responses from a public device to a node through an exit node, the destination is the Tailscale IP address, but the protocol, destination port, and source are empty. Tailscale doesn't gather granular information about individual connections to preserve privacy. If an administrator enables Destination Logging, the protocol, source port, and destination information are logged.

Start and end times are specific to the node that generated the message. Timestamps may be subject to clock skew across different nodes.

The virtual, subnet, exit, and physical traffic counters consist of the following components:

proto: The IANA Protocol Number for the network flow: 6 for TCP, 17 for UDP. Empty for exit traffic.
src: The Tailscale IP address and port for the source of the network flow. The port number is not included for exit traffic.
dst: The IP address and port for the destination of the network flow. This IP address can be either a Tailscale IP address or an external IP address, such as on a private network or a public IP. Empty for exit traffic, unless Destination Logging is enabled.
txPackets: Number of packets transmitted.
txBytes: Number of bytes transmitted.
rxPackets: Number of packets received.
rxBytes: Number of bytes received.

Enable network flow logs

Network flow logs are disabled by default.

You must be an Owner, Admin, Network admin, or IT admin of a tailnet to enable Network flow logs.

Open the Network flow logs page of the admin console.
Select Start logging.
In the Start logging network flows dialog, select Start logging.

Disable network flow logs

You must be an Owner, Admin, Network admin, or IT admin of a tailnet to disable Network flow logs.

Open the Network flow logs page of the admin console.
Select Stop logging.
In the Stop logging network flows dialog, select Stop logging.

Access network logs

You must be an Owner, Admin, Network admin, or IT admin of a tailnet to access network logs.

You can access network logs using the Tailscale API or log streaming.

Access network logs through the API

You need an API access token with the logs:network:read scope to access network logs.

The response from the https://api.tailscale.com/api/v2/tailnet/{$TAILNET_ID}/logging/network endpoint call is in the form of the Response struct:

type Response struct {
	Logs []Message `json:"logs"`
}

Using Golang syntax, the Response struct contains a slice of Message types. The Message struct is defined as:

type Message struct {
	// NodeID is the stable ID of the node that
	// generated this network log message.
	NodeID string `json:"nodeId"` // for example, "n123456CNTRL"

	// Logged is the timestamp of when the Tailscale logs service
	// recorded the network log message from a given node.
	// It is guaranteed to be within the start and end time ranges
	// specified in the API request.
	// All log messages are listed in chronological order
	// from oldest to newest.
	Logged time.Time `json:"logged"`

	// Start and End are the inclusive time ranges for the network
	// traffic flow information present in the message.
	// These timestamps are recorded by the node and subject
	// to clock skew across different nodes.
	// Generally speaking, the Logged timestamp is after End.
	//
	// Network logs are gathered in 5 second windows.
	// This may change in the future.
	Start time.Time `json:"start"`
	End time.Time `json:"end"`

	// VirtualTraffic records connection statistics for
	// node to node traffic.
	// Both the source and address are Tailscale IP addresses
	// (for example, 100.xx.xx.xx). The source is always the
	// Tailscale IP address of the current node.
	VirtualTraffic []ConnectionCounts `json:"virtualTraffic"`

	// SubnetTraffic records node to external traffic
	// on an explicitly advertised subnet route.
	//
	// For nodes using a subnet router,
	// the source is the Tailscale IP address of the current node.
	// For nodes operating as the subnet router,
	// the source is the Tailscale IP address of the node
	// using the subnet router.
	// The destination address is always the external IP address
	// within the advertised subnet range.
	SubnetTraffic []ConnectionCounts `json:"subnetTraffic"`

	// ExitTraffic records aggregated statistics for all traffic
	// flowing through an exit node. For traffic from a node to a
	// public device through an exit node, the source will be the
	// Tailscale IP address, but the protocol, source port,
	// and destination will be empty. For traffic responses from a
	// public device to a node through an exit node, the destination
	// will be the Tailscale IP address, but the protocol,
	// destination port and source will be empty. Fine
	// granularity information about individual connections is not
	// gathered so that privacy can be preserved.
	ExitTraffic []ConnectionCounts `json:"exitTraffic"`

	// PhysicalTraffic records traffic on the physical network layer
	// that operates below the virtual Tailscale network.
	// The source is the Tailscale IP address of remote nodes
	// that the current node is communicating with and
	// the destination is the external IP address that traffic
	// is physically sent to to communicate with that
	// remote node.
	//
	// Traffic information at the physical layer is gathered
	// at a slightly different moment in time as the virtual layer,
	// so packets flowing through the virtual layer
	// may not exactly line up with those at the physical layer.
	PhysicalTraffic []ConnectionCounts `json:"physicalTraffic"`
}

Several fields in the Message struct use the type ConnectionCounts. The ConnectionCounts struct is defined as:

type ConnectionCounts struct {
	Proto uint8  `json:"proto"` // for example, 6 for TCP, 17 for UDP
	Src   string `json:"src"`   // for example, "100.11.22.33:4567"
	Dst   string `json:"dst"`   // for example, "192.555.66.77:80"

	TxPackets uint64 `json:"txPkts"` // transferred packets
	TxBytes   uint64 `json:"txBytes"` // transferred bytes
	RxPackets uint64 `json:"rxPkts"` // received packets
	RxBytes   uint64 `json:"rxBytes"` // received bytes
}

The Message.NodeID field is verified by the Tailscale logs service as the actual node from which the message originated. The Start, End, VirtualTraffic, SubnetTraffic, ExitTraffic, and PhysicalTraffic fields are produced by individual nodes and recorded by the Tailscale logs service without validation. It is infeasible for Tailscale to verify the accuracy or truthfulness of this information. It is possible for malicious nodes to spoof this information.

When investigating network flow logs, you should identify a set of nodes that you consider more trustworthy (such as a server running in production) in contrast to those that might be more easily tampered with (such as an individual employee's work laptop). Discrepancies in network logs between the two might be indicative of malicious behavior.

You can use the following query parameters with the API:

start: Required. Start of the timeframe, in RFC 3339 timestamp format, for the logs to retrieve. For example: 2022-07-20T00:00:00Z.
end: Required. End of the timeframe, in RFC3339 timestamp format, for the logs to retrieve. If end is greater than the latest known timestamp in the log, the API call will not block the call. This means consecutive queries with the same start and end times range may return different log entries that were not available during the earlier query.

start and end times are inclusive within nanosecond resolution.

All log messages are listed in chronological order from oldest to newest.

There is no pagination support or maximum page size for the API. All known logged network activity in the specified timeframe is returned.

Example API call

This example assumes you have set up the following variables to use for your API call:

$ACCESS_TOKEN: An API access token to use when calling the Tailscale API. You can create an API access token in the Keys page of the admin console.
$TAILNET_ID: The organization name for the tailnet whose logs are being retrieved. You can view your organization name in the General settings page of the admin console.
$START: The start of the timeframe for the logs to retrieve.
$END: The end of the timeframe for the logs to retrieve.

export ACCESS_TOKEN=tskey-api-k123456CNTRL-0123456789abcdef
export TAILNET_ID=example.com
export START=2022-10-28T22:40:00.000000000Z
export END=2022-10-28T22:40:04.999999999Z

This example makes a call to the https://api.tailscale.com/api/v2/tailnet/{$TAILNET_ID}/logging/network endpoint.

curl -u $ACCESS_TOKEN: \
  "https://api.tailscale.com/api/v2/tailnet/{$TAILNET_ID}/logging/network?start={$START}&end={$END}"

(You can also copy the command above from the Network flow logs page of the admin console.)

The following code block contains an example log output:

{
	"logs": [
		{
			"nodeId": "aBcdef1CNTRL",
			"logged": "2022-10-28T22:40:00.290605382Z",
			"start": "2022-10-28T22:39:51.890385065Z",
			"end": "2022-10-28T22:39:56.886545512Z",
			"virtualTraffic": [
				{
					"proto": 6,
					"src": "100.111.22.33:21291",
					"dst": "100.111.44.55:63281",
					"txPkts": 2,
					"txBytes": 108,
					"rxPkts": 2,
					"rxBytes": 112
				},
				{
					"proto": 6,
					"src": "100.111.22.33:864",
					"dst": "100.44.55.66:2049",
					"txPkts": 6,
					"txBytes": 900,
					"rxPkts": 3,
					"rxBytes": 728
				},
				{
					"proto": 6,
					"src": "100.111.22.33:723",
					"dst": "100.99.888.77:2049",
					"txPkts": 4,
					"txBytes": 596,
					"rxPkts": 2,
					"rxBytes": 432
				},
				{
					"proto": 6,
					"src": "100.111.22.33:21291",
					"dst": "100.111.44.55:63280",
					"txPkts": 2,
					"txBytes": 108,
					"rxPkts": 2,
					"rxBytes": 112
				}
			],
			"physicalTraffic": [
				{
					"src": "100.111.44.55:0",
					"dst": "192.555.66.77:41641",
					"txPkts": 4,
					"txBytes": 384,
					"rxPkts": 4,
					"rxBytes": 384
				},
				{
					"src": "100.44.55.66:0",
					"dst": "192.168.0.101:41641",
					"txPkts": 6,
					"txBytes": 1136,
					"rxPkts": 3,
					"rxBytes": 848
				},
				{
					"src": "100.99.888.77:0",
					"dst": "143.110.111.222:41641",
					"txPkts": 4,
					"txBytes": 752,
					"rxPkts": 2,
					"rxBytes": 512
				}
			]
		},
		{
			"nodeId": "uvwXyz2CNTRL",
			"logged": "2022-10-28T22:40:00.344979725Z",
			"start": "2022-10-28T22:39:53.286643402Z",
			"end": "2022-10-28T22:39:58.286028244Z",
			"virtualTraffic": [
				{
					"proto": 6,
					"src": "100.44.55.66:49284",
					"dst": "100.99.888.77:22",
					"txPkts": 5,
					"txBytes": 440,
					"rxPkts": 10,
					"rxBytes": 1180
				},
				{
					"proto": 6,
					"src": "100.44.55.66:49282",
					"dst": "100.99.888.77:22",
					"txPkts": 5,
					"txBytes": 440,
					"rxPkts": 10,
					"rxBytes": 1180
				},
				{
					"proto": 6,
					"src": "100.44.55.66:49286",
					"dst": "100.99.888.77:22",
					"txPkts": 5,
					"txBytes": 440,
					"rxPkts": 9,
					"rxBytes": 968
				},
				{
					"proto": 6,
					"src": "100.44.55.66:49278",
					"dst": "100.99.888.77:22",
					"txPkts": 5,
					"txBytes": 440,
					"rxPkts": 10,
					"rxBytes": 1180
				},
				{
					"proto": 6,
					"src": "100.44.55.66:37500",
					"dst": "100.66.77.88:22",
					"txPkts": 46,
					"txBytes": 7416,
					"rxPkts": 68,
					"rxBytes": 12612
				},
				{
					"proto": 6,
					"src": "100.44.55.66:49288",
					"dst": "100.99.888.77:22",
					"txPkts": 64,
					"txBytes": 6236,
					"rxPkts": 104,
					"rxBytes": 10412
				},
				{
					"proto": 6,
					"src": "100.44.55.66:49280",
					"dst": "100.99.888.77:22",
					"txPkts": 5,
					"txBytes": 440,
					"rxPkts": 10,
					"rxBytes": 1180
				},
				{
					"proto": 6,
					"src": "100.44.55.66:2049",
					"dst": "100.111.22.33:864",
					"txPkts": 3,
					"txBytes": 728,
					"rxPkts": 6,
					"rxBytes": 900
				},
				{
					"proto": 1,
					"src": "100.44.55.66:0",
					"dst": "100.99.888.77:0",
					"txPkts": 5,
					"txBytes": 420,
					"rxPkts": 5,
					"rxBytes": 420
				}
			],
			"physicalTraffic": [
				{
					"src": "100.33.444.55:0",
					"dst": "98.97.111.222:2705",
					"txPkts": 1,
					"txBytes": 32
				},
				{
					"src": "100.111.22.33:0",
					"dst": "192.168.0.102:41641",
					"txPkts": 3,
					"txBytes": 848,
					"rxPkts": 6,
					"rxBytes": 1136
				},
				{
					"src": "100.99.888.77:0",
					"dst": "143.110.111.222:41641",
					"txPkts": 94,
					"txBytes": 12672,
					"rxPkts": 158,
					"rxBytes": 23104
				},
				{
					"src": "100.66.77.88:0",
					"dst": "64.71.111.222:41641",
					"txPkts": 46,
					"txBytes": 9296,
					"rxPkts": 68,
					"rxBytes": 15392
				}
			]
		}
	]
}

You can use the Go binary netlogfmt to make the output more readable:

curl -u $ACCESS_TOKEN: \
  "https://api.tailscale.com/api/v2/tailnet/{$TAILNET_ID}/logging/network?start={$START}&end={$END}" \
  | go run tailscale.com/cmd/netlogfmt@latest

The following code block contains an example log output:

===========================================================================================
NodeID: aBcdef1CNTRL
Logged: 2022-10-28 15:40:00.290
Window: 2022-10-28 15:39:51.890 (4.996s)
-----------------------------------------------------  Tx[P/s]   Tx[B/s]  Rx[P/s]   Rx[B/s]
VirtualTraffic:                                          2.80   342.66      1.80   277.01
    TCP:   100.111.22.33:864 -> 100.44.55.66:2049        1.20   180.14      0.60   145.71
    TCP:   100.111.22.33:723 -> 100.99.888.77:2049       0.80   119.29      0.40    86.47
    TCP: 100.111.22.33:21291 -> 100.111.44.55:63281      0.40    21.62      0.40    22.42
    TCP: 100.111.22.33:21291 -> 100.111.44.55:63280      0.40    21.62      0.40    22.42
PhysicalTraffic:                                         2.80   454.75      1.80   349.07
                100.44.55.66 -> 192.168.0.101:41641      1.20   227.37      0.60   169.73
               100.99.888.77 -> 143.111.222.333:41641    0.80   150.52      0.40   102.48
               100.111.44.55 -> 192.555.66.77:41641      0.80    76.86      0.80    76.86
=============================================================================================
NodeID: uvwXyz2CNTRL
Logged: 2022-10-28 15:40:00.344
Window: 2022-10-28 15:39:53.286 (4.999s)
-------------------------------------------------------  Tx[P/s]   Tx[B/s]  Rx[P/s]   Rx[B/s]
VirtualTraffic:                                           28.60     3.32Ki   46.41     5.87Ki
    TCP:    100.44.55.66:37500 -> 100.103.145.6:22         9.20     1.45Ki   13.60     2.46Ki
    TCP:    100.44.55.66:49288 -> 100.99.888.77:22        12.80     1.22Ki   20.80     2.03Ki
    TCP:     100.44.55.66:2049 -> 100.111.22.33:864        0.60   145.62      1.20   180.02
    TCP:    100.44.55.66:49284 -> 100.99.888.77:22         1.00    88.01      2.00   236.03
    TCP:    100.44.55.66:49282 -> 100.99.888.77:22         1.00    88.01      2.00   236.03
    TCP:    100.44.55.66:49278 -> 100.99.888.77:22         1.00    88.01      2.00   236.03
    TCP:    100.44.55.66:49280 -> 100.99.888.77:22         1.00    88.01      2.00   236.03
    TCP:    100.44.55.66:49286 -> 100.99.888.77:22         1.00    88.01      1.80   193.62
    ICMPv4:       100.44.55.66 -> 100.99.888.77            1.00    84.01      1.00    84.01
PhysicalTraffic:                                          28.80     4.46Ki   46.41     7.74Ki
                 100.99.888.77 -> 143.111.222.333:41641   18.80     2.48Ki   31.60     4.51Ki
                 100.103.145.6 -> 64.71.162.170:41641      9.20     1.82Ki   13.60     3.01Ki
                 100.111.22.33 -> 192.168.0.102:41641      0.60   169.62      1.20   227.23

To make it easier to recognize nodes in the output, the netlogfmt binary provides flags that resolve IP addresses to readable hostnames:

--resolve-names: Convert tailscale IP addresses to hostnames. You must also specify --api-key and --tailnet-name as parameters to netlogfmt when you use the --resolve-names flag.
--api-key: Specifies the API access token to use for the Tailscale API. This can be the same API access token you used for the network-logs endpoint or another valid API access token.
--tailnet-name: The same organization name you passed to the network-logs endpoint.

This example shows how to use the netlogfmt flags:

curl -u $ACCESS_TOKEN:  -X GET \
  "https://api.tailscale.com/api/v2/tailnet/{$TAILNET_ID}/logging/network?start={$START}&end={$END}" \
  | go run tailscale.com/cmd/netlogfmt@latest -- \
      --resolve-names --api-key=$ACCESS_TOKEN --tailnet-name=$TAILNET

The following code block contains an example log output.

=======================================================================================
NodeID: aBcdef1CNTRL
Logged: 2022-10-28 15:40:00.290
Window: 2022-10-28 15:39:51.890 (4.996s)
-------------------------------------------------  Tx[P/s]   Tx[B/s]  Rx[P/s]   Rx[B/s]
VirtualTraffic:                                      2.80   342.66      1.80   277.01
    TCP:   carbonite:864 -> prism:2049               1.20   180.14      0.60   145.71
    TCP:   carbonite:723 -> diamond:2049             0.80   119.29      0.40    86.47
    TCP: carbonite:21291 -> glass:63281              0.40    21.62      0.40    22.42
    TCP: carbonite:21291 -> glass:63280              0.40    21.62      0.40    22.42
PhysicalTraffic:                                     2.80   454.75      1.80   349.07
                   prism -> 192.168.0.101:41641      1.20   227.37      0.60   169.73
                 diamond -> 143.110.111.222:41641    0.80   150.52      0.40   102.48
                   glass -> 192.555.66.77:41641      0.80    76.86      0.80    76.86
======================================================================================
NodeID: uvwXyz2CNTRL
Logged: 2022-10-28 15:40:00.344
Window: 2022-10-28 15:39:53.286 (4.999s)
------------------------------------------------  Tx[P/s]   Tx[B/s]  Rx[P/s]   Rx[B/s]
VirtualTraffic:                                    28.60     3.32Ki   46.41     5.87Ki
    TCP:    prism:37500 -> glass:22                 9.20     1.45Ki   13.60     2.46Ki
    TCP:    prism:49288 -> diamond:22              12.80     1.22Ki   20.80     2.03Ki
    TCP:     prism:2049 -> carbonite:864            0.60   145.62      1.20   180.02
    TCP:    prism:49284 -> diamond:22               1.00    88.01      2.00   236.03
    TCP:    prism:49282 -> diamond:22               1.00    88.01      2.00   236.03
    TCP:    prism:49278 -> diamond:22               1.00    88.01      2.00   236.03
    TCP:    prism:49280 -> diamond:22               1.00    88.01      2.00   236.03
    TCP:    prism:49286 -> diamond:22               1.00    88.01      1.80   193.62
    ICMPv4:       prism -> diamond                  1.00    84.01      1.00    84.01
PhysicalTraffic:                                   28.80     4.46Ki   46.41     7.74Ki
                diamond -> 143.110.111.222:41641   18.80     2.48Ki   31.60     4.51Ki
                  glass -> 64.71.111.222:41641      9.20     1.82Ki   13.60     3.01Ki
              carbonite -> 192.168.0.102:41641      0.60   169.62      1.20   227.23

Network flow logs streaming

Log streaming lets you stream network flow logs into a security information and event management (SIEM) system. For more information, refer to Log streaming.

Limitations

Only nodes using Tailscale v1.34 or later send networking telemetry to the Tailscale logs service.
You can only access network logs using the API and as a streaming source for SIEM systems. There is no network logs viewing functionality in the Tailscale admin console.
Network flow logs are for logging, not monitoring. The admin console does not contain a live view of the connections between nodes. Additionally, network logs don't include information on whether a node is online or idle. The logs only indicate whether there was network traffic.
Network logs do not include individual packet transfers. Logs capture when connections are active, which could include multiple data flows.
Tailscale only logs successful connects. If a connection attempt results in denied access, the attempt isn't logged.
Traffic information at the physical layer is gathered at a slightly different time than the virtual layer, so packets flowing through the virtual layer might not precisely line up with those at the physical layer.
Public IP addresses are not logged as either a destination or source. That is, a connection from your tailnet through an exit node does not log where the traffic is going, and a connection from the public internet through an exit node does not log where the traffic is returning from. To preserve privacy, Tailscale doesn't gather detailed information about individual connections.
- If Destination Logging is enabled by the administrator, the protocol, source port, and destination information are logged.
The user authenticated on a source or destination host is not logged. To map a node to a user, you can use the /api/v2/tailnet/:tailnet/device method and examine the user field.
Network logging is performed client-side. Tailscale cannot guarantee the delivery or integrity of the client logs. Tailscale cannot fully guarantee client log latency thresholds—that is, logs are not delivered in real-time.
Enabling network flow logs might result in a slight performance impact because the client does additional work to track necessary metrics. The incremental load is spread across the fleet, not concentrated on a single host.