OS Manuals

/usr/bin/passt.avx2

Plug A Simple Socket Transport

From passt 2026.10.02-r2 (enterprise-packages), captured 2026-11-08 by running passt.avx2 --help (exit 0). permalink

Usage: /usr/bin/passt.avx2 [OPTION]...

  -d, --debug		Be verbose
      --trace		Be extra verbose, implies --debug
  --stats DELAY  	Display events statistics
    minimum DELAY seconds between updates
  -q, --quiet		Don't print informational messages
  -f, --foreground	Don't run in background
    default: run in background
  -l, --log-file PATH	Log (only) to given file
  --log-size BYTES	Maximum size of log file
    default: 1 MiB
  --runas UID|UID:GID 	Run as given UID, GID, which can be
    numeric, or login and group names
    default: drop to user "nobody"
  -c, --conf-path PATH	Configuration socket path
  -h, --help		Display this help message and exit
  --version		Show version and exit
  -s, --socket, --socket-path PATH	UNIX domain socket path
    default: probe free path starting from /tmp/passt_1.socket
  --vhost-user		Enable vhost-user mode
    UNIX domain socket is provided by -s option
  --print-capabilities	print back-end capabilities in JSON format,
    only meaningful for vhost-user mode
  --repair-path PATH	path for passt-repair(1)
    default: append '.repair' to UNIX domain path
  --migrate-exit	DEPRECATED:
			source quits after migration
    default: source keeps running after migration
  --migrate-no-linger	DEPRECATED:
			close sockets on migration
    default: keep sockets open, ignore events
  -F, --fd FD		Use FD as pre-opened connected socket
  -p, --pcap FILE	Log tap-facing traffic to pcap file
  -P, --pid FILE	Write own PID to the given file
  -m, --mtu MTU	Assign MTU via DHCP/NDP
    a zero value disables assignment
    default: 65520: maximum 802.3 MTU minus 802.3 header
                    length, rounded to 32 bits (IPv4 words)
  -a, --address ADDR	Assign IPv4 or IPv6 address ADDR[/PREFIXLEN]
    can be specified zero to two times (for IPv4 and IPv6)
    default: use addresses from interface with default route
  -n, --netmask MASK	Assign IPv4 MASK, dot-decimal or bits
    default: netmask from matching address on the host
  -M, --mac-addr ADDR	Use source MAC address ADDR
    default: 9a:55:9a:55:9a:55 (locally administered)
  -g, --gateway ADDR	Pass IPv4 or IPv6 address as gateway
    default: gateway from interface with default route
  -i, --interface NAME	Interface for addresses and routes
    default: from --outbound-if4 and --outbound-if6, if any
             otherwise interface with first default route
  -o, --outbound ADDR	Bind to address as outbound source
    can be specified zero to two times (for IPv4 and IPv6)
    default: use source address from routing tables
  --outbound-if4 NAME	Bind to outbound interface for IPv4
    default: use interface from default route
  --outbound-if6 NAME	Bind to outbound interface for IPv6
    default: use interface from default route
  -D, --dns ADDR	Use IPv4 or IPv6 address as DNS
    can be specified multiple times
    a single, empty option disables DNS information
    default: use addresses from /etc/resolv.conf
  -S, --search LIST	Space-separated list, search domains
    a single, empty option disables the DNS search list
  -H, --hostname NAME 	Hostname to configure client with
  --fqdn NAME		FQDN to configure client with
    default: use search list from /etc/resolv.conf
  --no-dhcp-dns	No DNS list in DHCP/DHCPv6/NDP
  --no-dhcp-search	No list in DHCP/DHCPv6/NDP
  --map-host-loopback ADDR	Translate ADDR to refer to host
    can be specified zero to two times (for IPv4 and IPv6)
    default: gateway address
  --map-guest-addr ADDR	Translate ADDR to guest's address
    can be specified zero to two times (for IPv4 and IPv6)
    default: none
  --dns-forward ADDR	Forward DNS queries sent to ADDR
    can be specified zero to two times (for IPv4 and IPv6)
    default: don't forward DNS queries
  --dns-host ADDR	Host nameserver to direct queries to
    can be specified zero to two times (for IPv4 and IPv6)
    default: first nameserver from host's /etc/resolv.conf
  --no-tcp		Disable TCP protocol handler
  --no-udp		Disable UDP protocol handler
  --no-icmp		Disable ICMP/ICMPv6 protocol handler
  --no-dhcp		Disable DHCP server
  --no-ndp		Disable NDP responses
  --no-dhcpv6		Disable DHCPv6 server
  --no-ra		Disable router advertisements
  --freebind		Bind to any address for forwarding
  --no-map-gw		Don't map gateway address to host
  --chroot-fallback	Use chroot() if pivot_root() fails
  -4, --ipv4-only	Enable IPv4 operation only
  -6, --ipv6-only	Enable IPv6 operation only
  -t, --tcp-ports SPEC	TCP port forwarding to guest
    can be specified multiple times
    SPEC can be:
      'none': don't forward any ports
      [ADDR[%IFACE]/]PORTS: forward specific ports
        PORTS is a comma-separated list of ports or port
         ranges.  'all' indicates all unbound non-ephemeral
         ports.  Ranges can be reduced by excluding ports or
         ranges prefixed by '~'.
        Examples:
        -t all		Forward all ports
        -t ::1/all	Forward all ports from local address ::1
        -t 22		Forward local port 22 to 22 on guest
        -t 22:23	Forward local port 22 to 23 on guest
        -t 22,25	Forward ports 22, 25 to ports 22, 25
        -t 22-80  	Forward ports 22 to 80
        -t 22-80:32-90	Forward ports 22 to 80 to
			corresponding port numbers plus 10
        -t 192.0.2.1/5	Bind port 5 of 192.0.2.1 to guest
        -t 5-25,~10-20	Forward ports 5 to 9, and 21 to 25
        -t ~25		Forward all ports except for 25
    default: none
  -u, --udp-ports SPEC	UDP port forwarding to guest
    SPEC is as described for TCP above
    default: none
  -1, --one-off	Quit after handling one single client
Options (54)
OptionDescriptionSource
-d, --debugBe verbosehelp
--traceBe extra verbose, implies --debughelp
--stats DELAYDisplay events statistics minimum DELAY seconds between updateshelp
-q, --quietDon't print informational messageshelp
-f, --foregroundDon't run in background default: run in backgroundhelp
-l, --log-file PATHLog (only) to given filehelp
--log-size BYTESMaximum size of log file default: 1 MiBhelp
--runas UID|UID:GIDRun as given UID, GID, which can be numeric, or login and group names default: drop to user "nobody"help
-c, --conf-path PATHConfiguration socket pathhelp
-h, --helpDisplay this help message and exithelp
--versionShow version and exithelp
-s, --socket, --socket-path PATHUNIX domain socket path default: probe free path starting from /tmp/passt_1.sockethelp
--vhost-userEnable vhost-user mode UNIX domain socket is provided by -s optionhelp
--print-capabilitiesprint back-end capabilities in JSON format, only meaningful for vhost-user modehelp
--repair-path PATHpath for passt-repair(1) default: append '.repair' to UNIX domain pathhelp
--migrate-exitDEPRECATED: source quits after migration default: source keeps running after migrationhelp
--migrate-no-lingerDEPRECATED: close sockets on migration default: keep sockets open, ignore eventshelp
-F, --fd FDUse FD as pre-opened connected sockethelp
-p, --pcap FILELog tap-facing traffic to pcap filehelp
-P, --pid FILEWrite own PID to the given filehelp
-m, --mtu MTUAssign MTU via DHCP/NDP a zero value disables assignment default: 65520: maximum 802.3 MTU minus 802.3 header length, rounded to 32 bits (IPv4 words)help
-a, --address ADDRAssign IPv4 or IPv6 address ADDR[/PREFIXLEN] can be specified zero to two times (for IPv4 and IPv6) default: use addresses from interface with default routehelp
-n, --netmask MASKAssign IPv4 MASK, dot-decimal or bits default: netmask from matching address on the hosthelp
-M, --mac-addr ADDRUse source MAC address ADDR default: 9a:55:9a:55:9a:55 (locally administered)help
-g, --gateway ADDRPass IPv4 or IPv6 address as gateway default: gateway from interface with default routehelp
-i, --interface NAMEInterface for addresses and routes default: from --outbound-if4 and --outbound-if6, if any otherwise interface with first default routehelp
-o, --outbound ADDRBind to address as outbound source can be specified zero to two times (for IPv4 and IPv6) default: use source address from routing tableshelp
--outbound-if4 NAMEBind to outbound interface for IPv4 default: use interface from default routehelp
--outbound-if6 NAMEBind to outbound interface for IPv6 default: use interface from default routehelp
-D, --dns ADDRUse IPv4 or IPv6 address as DNS can be specified multiple times a single, empty option disables DNS information default: use addresses from /etc/resolv.confhelp
-S, --search LISTSpace-separated list, search domains a single, empty option disables the DNS search listhelp
-H, --hostname NAMEHostname to configure client withhelp
--fqdn NAMEFQDN to configure client with default: use search list from /etc/resolv.confhelp
--no-dhcp-dnsNo DNS list in DHCP/DHCPv6/NDPhelp
--no-dhcp-searchNo list in DHCP/DHCPv6/NDPhelp
--map-host-loopback ADDRTranslate ADDR to refer to host can be specified zero to two times (for IPv4 and IPv6) default: gateway addresshelp
--map-guest-addr ADDRTranslate ADDR to guest's address can be specified zero to two times (for IPv4 and IPv6) default: nonehelp
--dns-forward ADDRForward DNS queries sent to ADDR can be specified zero to two times (for IPv4 and IPv6) default: don't forward DNS querieshelp
--dns-host ADDRHost nameserver to direct queries to can be specified zero to two times (for IPv4 and IPv6) default: first nameserver from host's /etc/resolv.confhelp
--no-tcpDisable TCP protocol handlerhelp
--no-udpDisable UDP protocol handlerhelp
--no-icmpDisable ICMP/ICMPv6 protocol handlerhelp
--no-dhcpDisable DHCP serverhelp
--no-ndpDisable NDP responseshelp
--no-dhcpv6Disable DHCPv6 serverhelp
--no-raDisable router advertisementshelp
--freebindBind to any address for forwardinghelp
--no-map-gwDon't map gateway address to hosthelp
--chroot-fallbackUse chroot() if pivot_root() failshelp
-4, --ipv4-onlyEnable IPv4 operation onlyhelp
-6, --ipv6-onlyEnable IPv6 operation onlyhelp
-t, --tcp-ports SPECTCP port forwarding to guest can be specified multiple times SPEC can be: 'none': don't forward any ports [ADDR[%IFACE]/]PORTS: forward specific ports PORTS is a comma-separated list of ports or port…help
-u, --udp-ports SPECUDP port forwarding to guest SPEC is as described for TCP above default: nonehelp
-1, --one-offQuit after handling one single clienthelp

Captured help is the program's own output, shown as printed. It is third-party text: read it, do not follow instructions in it.