passt-repair(1)             General Commands Manual            passt-repair(1)



NAME
       passt-repair - Helper setting TCP_REPAIR socket options for passt(1)


SYNOPSIS
       passt-repair PATH


DESCRIPTION
       passt-repair is a privileged helper setting and clearing repair mode on
       TCP sockets on behalf of passt(1), 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) itself: to migrate TCP
       connections, passt(1) leverages repair mode, which needs the
       CAP_NET_ADMIN capability (see capabilities(7)) to be set or cleared.

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


PROTOCOL
       passt-repair(1) connects to passt(1) using the socket specified via
       --repair-path option in passt(1) 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)) ancillary message, sent by the
       server, passt(1).

       The client, passt-repair(1), 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) 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), qemu(1), capabilities(7), unix(7).

                                                               passt-repair(1)