---
name: "hwstamp_ctl"
section: "8"
platform: "linux"
package: "linuxptp"
version: "4.4-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/hwstamp_ctl"
---

# hwstamp\_ctl(8)

set time stamping policy at the driver level

## NAME

hwstamp\_ctl - set time stamping policy at the driver level

## SYNOPSIS

**hwstamp\_ctl** **-i** *interface* \[ **-r** *rx-filter* \] \[ **-t** *tx-type* \] \[ **-v** \]

## DESCRIPTION

**hwstamp\_ctl** is a program used to set and get the hardware time stamping policy at the network driver level with the **SIOCSHWTSTAMP** [**ioctl**(2)](/ioctl/2.md). The *tx-type* and *rx-filter* values are hints to the driver what it is expected to do. If the requested fine-grained filtering for incoming packets is not supported, the driver may time stamp more than just the requested types of packets.

If neither *tx-type* nor *rx-filter* values are passed to the program, it will use the **SIOCGHWTSTAMP** **[ioctl(2)](/ioctl/2.md)** to non-destructively read the current hardware time stamping policy.

This program is a debugging tool. The [**ptp4l**(8)](/ptp4l/8.md) program does not need this program to function, it will set the policy automatically as appropriate.

## OPTIONS

- **-i** *interface*

  Specify the network interface of which the policy should be changed.

- **-r** *rx-filter*

  Specify which types of incoming packets should be time stamped, *rx-filter* is an integer value.

- **-t** *tx-type*

  Enable or disable hardware time stamping for outgoing packets, *tx-type* is an integer value.

- **-h**

  Display a help message and list of possible values for *rx-filter* and *tx-type*.

- **-v**

  Prints the software version and exits.

## SEE ALSO

[**ioctl**(2)](/ioctl/2.md), [**ptp4l**(8)](/ptp4l/8.md)