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     dtrace_udp — a DTrace provider for tracing events related to the UDP protocol


     udp:::receive(pktinfo_t *, csinfo_t *, ipinfo_t *, udpsinfo_t *, udpinfo_t *);

     udp:::send(pktinfo_t *, csinfo_t *, ipinfo_t *, udpsinfo_t *, udpinfo_t *);


     The DTrace udp provider allows users to trace events in the udp(4) protocol implementation.
     The udp:::send() probe fires whenever the kernel prepares to transmit a UDP packet, and the
     udp:::receive() probe fires whenever the kernel receives a UDP packet, unless the UDP header
     is incomplete, the destination port is 0, the length field is invalid, or the checksum is
     wrong.  The arguments to these probes can be used to obtain detailed information about the
     IP and UDP headers of the corresponding packet.


     The pktinfo_t argument is currently unimplemented and is included for compatibility with
     other implementations of this provider.  Its fields are:

           uintptr_t pkt_addr  Always set to 0.

     The csinfo_t argument is currently unimplemented and is included for compatibility with
     other implementations of this provider.  Its fields are:

           uintptr_t cs_addr  Always set to 0.

           uint64_t cs_cid    A pointer to the struct inpcb for this packet, or NULL.

           pid_t cs_pid       Always set to 0.

     The ipinfo_t argument contains IP fields common to both IPv4 and IPv6 packets.  Its fields

           uint8_t ip_ver       IP version of the packet, 4 for IPv4 packets and 6 for IPv6

           uint32_t ip_plength  IP payload size.  This does not include the size of the IP header
                                or IPv6 option headers.

           string ip_saddr      IP source address.

           string ip_daddr      IP destination address.

     The udpsinfo_t argument contains the state of the UDP connection associated with the packet.
     Its fields are:

           uintptr_t udps_addr  Pointer to the struct inpcb containing the IP state for the
                                associated socket.

           uint16_t udps_lport  Local UDP port.

           uint16_t udps_rport  Remote UDP port.

           string udps_laddr    Local IPv4 or IPv6 address.

           string udps_raddr    Remote IPv4 or IPv6 address.

     The udpinfo_t argument is the raw UDP header of the packet, with all fields in host order.
     Its fields are:

           uint16_t udp_sport      Source UDP port.

           uint16_t udp_dport      Destination UDP port.

           uint16_t udp_length     Length of the UDP header and payload, in bytes.

           uint16_t udp_checksum   A checksum of the UDP header and payload, or 0 if no checksum
                                   was calculated.

           struct udphdr *udp_hdr  A pointer to the raw UDP header.


     /usr/lib/dtrace/udp.d  DTrace type and translator definitions for the udp provider.


     The following script counts transmitted packets by destination port.

                   @num[args[4]->udp_dport] = count();

     This script will print some details of each UDP packet as it is sent or received by the

           #pragma D option quiet
           #pragma D option switchrate=10Hz

                   printf(" %10s %36s    %-36s %6s\n", "DELTA(us)", "SOURCE",
                       "DEST", "BYTES");
                   last = timestamp;

                   this->elapsed = (timestamp - last) / 1000;
                   self->dest = strjoin(strjoin(args[2]->ip_daddr, ":"),
                   printf(" %10d %30s:%-5d -> %-36s %6d\n", this->elapsed,
                       args[2]->ip_saddr, args[4]->udp_sport,
                       self->dest, args[4]->udp_length);
                   last = timestamp;

                   this->elapsed = (timestamp - last) / 1000;
                   self->dest = strjoin(strjoin(args[2]->ip_saddr, ":"),
                   printf(" %10d %30s:%-5d <- %-36s %6d\n", this->elapsed,
                       args[2]->ip_daddr, args[4]->udp_dport,
                       self->dest, args[4]->udp_length);
                   last = timestamp;


     This provider is compatible with the udp provider in Solaris.


     dtrace(1), dtrace_ip(4), dtrace_sctp(4), dtrace_tcp(4), dtrace_udplite(4), udp(4), SDT(9)


     The udp provider first appeared in FreeBSD 10.0.


     This manual page was written by Mark Johnston <>.