---
name: "passt-repair"
section: "1"
platform: "linux"
package: "passt"
version: "2026_10_02.cba3570-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/passt-repair"
---

# passt-repair(1)

Helper setting TCP\_REPAIR socket options for passt(1)

## NAME

**passt-repair** - Helper setting TCP\_REPAIR socket options for [**passt**(1)](/passt/1.md)

## SYNOPSIS

**passt-repair** *PATH*

## DESCRIPTION

**passt-repair** is a privileged helper setting and clearing repair mode on TCP sockets on behalf of [**passt**(1)](/passt/1.md), as instructed via single-byte commands over a UNIX domain socket.

It can be used to migrate TCP connections between guests without granting additional capabilities to [**passt**(1)](/passt/1.md) itself: to migrate TCP connections, [**passt**(1)](/passt/1.md) leverages repair mode, which needs the **CAP\_NET\_ADMIN** capability (see [**capabilities**(7)](/capabilities/7.md)) to be set or cleared.

If *PATH* represents a UNIX domain socket, [**passt-repair**(1)](/passt-repair/1.md) attempts to connect to it. If it is a directory, [**passt-repair**(1)](/passt-repair/1.md) waits until a file ending with *.repair* appears in it, and then attempts to connect to it.

## PROTOCOL

[**passt-repair**(1)](/passt-repair/1.md) connects to [**passt**(1)](/passt/1.md) using the socket specified via *--repair-path* option in [**passt**(1)](/passt/1.md) itself. By default, the name is the same as the UNIX domain socket used for guest communication, suffixed by *.repair*.

The messages consist of one 8-bit signed integer that can be *TCP\_REPAIR\_ON* (1), *TCP\_REPAIR\_OFF* (0), or *TCP\_REPAIR\_OFF\_NO\_WP* (-1), as defined by the Linux kernel user API, and one to SCM\_MAX\_FD (253) sockets as SCM\_RIGHTS (see [**unix**(7)](/unix/7.md)) ancillary message, sent by the server, [**passt**(1)](/passt/1.md).

The client, [**passt-repair**(1)](/passt-repair/1.md), replies with the same byte (and no ancillary message) to indicate success, and closes the connection on failure.

The server closes the connection on error or completion.

## NOTES

[**passt-repair**(1)](/passt-repair/1.md) can be granted the **CAP\_NET\_ADMIN** capability (preferred, as it limits privileges to the strictly necessary ones), or it can be run as root.

## AUTHOR

Stefano Brivio \<sbrivio@redhat.com\>.

## REPORTING BUGS

Please report issues on the bug tracker at https://bugs.passt.top/, or send a message to the passt-user@passt.top mailing list, see https://lists.passt.top/.

## COPYRIGHT

Copyright (c) 2025 Red Hat GmbH.

**passt-repair** is free software: you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

## SEE ALSO

[**passt**(1)](/passt/1.md), [**qemu**(1)](/qemu/1.md), [**capabilities**(7)](/capabilities/7.md), [**unix**(7)](/unix/7.md).