ff46e28acc
Fire UDP receive probes when a packet is received and there is no endpoint consuming it. Fire the probe also if the TTL of the received packet is smaller than the minimum required by the endpoint. Clarify also in the man page, when the probe fires. Reviewed by: dteske@, markj@, rrs@ Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D16046
204 lines
5.9 KiB
Groff
204 lines
5.9 KiB
Groff
.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 20, 2018
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.Dt DTRACE_UDP 4
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.Os
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.Sh NAME
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.Nm dtrace_udp
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.Nd a DTrace provider for tracing events related to the UDP protocol
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.Sh SYNOPSIS
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.Fn udp:::receive "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "udpsinfo_t *" \
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"udpinfo_t *"
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.Fn udp:::send "pktinfo_t *" "csinfo_t *" "ipinfo_t *" "udpsinfo_t *" \
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"udpinfo_t *"
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.Sh DESCRIPTION
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The DTrace
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.Nm udp
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provider allows users to trace events in the
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.Xr udp 4
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protocol implementation.
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The
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.Fn udp:::send
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probe fires whenever the kernel prepares to transmit a UDP packet, and the
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.Fn udp:::receive
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probe fires whenever the kernel receives a UDP packet, unless
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the UDP header is incomplete,
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the destination port is 0,
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the length field is invalid,
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or the checksum is wrong.
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The arguments to these probes can be used to obtain detailed information about
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the IP and UDP headers of the corresponding packet.
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.Sh ARGUMENTS
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The
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.Vt pktinfo_t
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argument is currently unimplemented and is included for compatibility with other
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implementations of this provider.
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Its fields are:
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.Bl -tag -width "uintptr_t pkt_addr" -offset indent
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.It Vt uintptr_t pkt_addr
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Always set to 0.
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.El
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.Pp
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The
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.Vt csinfo_t
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argument is currently unimplemented and is included for compatibility with other
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implementations of this provider.
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Its fields are:
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.Bl -tag -width "uintptr_t cs_addr" -offset indent
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.It Vt uintptr_t cs_addr
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Always set to 0.
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.It Vt uint64_t cs_cid
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A pointer to the
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.Vt struct inpcb
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for this packet, or
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.Dv NULL .
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.It Vt pid_t cs_pid
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Always set to 0.
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.El
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.Pp
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The
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.Vt ipinfo_t
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argument contains IP fields common to both IPv4 and IPv6 packets.
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Its fields are:
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.Bl -tag -width "uint32_t ip_plength" -offset indent
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.It Vt uint8_t ip_ver
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IP version of the packet, 4 for IPv4 packets and 6 for IPv6 packets.
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.It Vt uint32_t ip_plength
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IP payload size.
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This does not include the size of the IP header or IPv6 option headers.
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.It Vt string ip_saddr
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IP source address.
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.It Vt string ip_daddr
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IP destination address.
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.El
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.Pp
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The
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.Vt udpsinfo_t
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argument contains the state of the UDP connection associated with the packet.
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Its fields are:
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.Bl -tag -width "uintptr_t udps_addr" -offset indent
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.It Vt uintptr_t udps_addr
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Pointer to the
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.Vt struct inpcb
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containing the IP state for the associated socket.
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.It Vt uint16_t udps_lport
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Local UDP port.
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.It Vt uint16_t udps_rport
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Remote UDP port.
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.It Vt string udps_laddr
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Local IPv4 or IPv6 address.
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.It Vt string udps_raddr
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Remote IPv4 or IPv6 address.
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.El
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.Pp
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The
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.Vt udpinfo_t
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argument is the raw UDP header of the packet, with all fields in host order.
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Its fields are:
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.Bl -tag -width "struct udphdr *udp_hdr" -offset indent
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.It Vt uint16_t udp_sport
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Source UDP port.
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.It Vt uint16_t udp_dport
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Destination UDP port.
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.It Vt uint16_t udp_length
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Length of the UDP header and payload, in bytes.
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.It Vt uint16_t udp_checksum
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A checksum of the UDP header and payload, or 0 if no checksum was calculated.
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.It Vt struct udphdr *udp_hdr
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A pointer to the raw UDP header.
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.El
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.Sh FILES
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.Bl -tag -width "/usr/lib/dtrace/udp.d" -compact
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.It Pa /usr/lib/dtrace/udp.d
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DTrace type and translator definitions for the
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.Nm udp
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provider.
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.El
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.Sh EXAMPLES
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The following script counts transmitted packets by destination port.
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.Bd -literal -offset indent
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udp:::send
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{
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@num[args[4]->udp_dport] = count();
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}
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.Ed
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.Pp
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This script will print some details of each UDP packet as it is sent or received
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by the kernel:
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.Bd -literal -offset indent
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#pragma D option quiet
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#pragma D option switchrate=10Hz
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dtrace:::BEGIN
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{
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printf(" %10s %36s %-36s %6s\\n", "DELTA(us)", "SOURCE",
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"DEST", "BYTES");
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last = timestamp;
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}
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udp:::send
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{
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this->elapsed = (timestamp - last) / 1000;
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self->dest = strjoin(strjoin(args[2]->ip_daddr, ":"),
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lltostr(args[4]->udp_dport));
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printf(" %10d %30s:%-5d -> %-36s %6d\\n", this->elapsed,
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args[2]->ip_saddr, args[4]->udp_sport,
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self->dest, args[4]->udp_length);
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last = timestamp;
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}
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udp:::receive
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{
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this->elapsed = (timestamp - last) / 1000;
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self->dest = strjoin(strjoin(args[2]->ip_saddr, ":"),
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lltostr(args[4]->udp_sport));
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printf(" %10d %30s:%-5d <- %-36s %6d\\n", this->elapsed,
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args[2]->ip_daddr, args[4]->udp_dport,
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self->dest, args[4]->udp_length);
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last = timestamp;
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}
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.Ed
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.Sh COMPATIBILITY
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This provider is compatible with the
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.Nm udp
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provider in Solaris.
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.Sh SEE ALSO
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.Xr dtrace 1 ,
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.Xr dtrace_ip 4 ,
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.Xr dtrace_tcp 4 ,
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.Xr udp 4 ,
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.Xr SDT 9
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.Sh HISTORY
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The
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.Nm udp
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provider first appeared in
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.Fx
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10.0.
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.Sh AUTHORS
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This manual page was written by
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.An Mark Johnston Aq Mt markj@FreeBSD.org .
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