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 com-
mands over a UNIX domain socket.
It can be used to migrate TCP connections between guests without grant-
ing additional capabilities to passt(1) itself: to migrate TCP connec-
tions, passt(1) leverages repair mode, which needs the CAP_NET_ADMIN ca-
pability (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_RE-
PAIR_ON (1), TCP_REPAIR_OFF (0), or TCP_REPAIR_OFF_NO_WP (-1), as de-
fined 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 ancil-
lary 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)
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