prtraceroute

PRTRACEROUTE(8)              System Manager's Manual             PRTRACEROUTE(8)



NAME
       prtraceroute - print the route and policy information packets take to a
       network host.


SYNOPSIS
       prtraceroute [ -m max_tll ] [ -n ] [ -n ] [ -p port ] [ -q nqueries ] [
       -r ] [ -s src_addr ] [ -t tos ] [ -v ] [ -w waittime ] host [ packetsize
       ]

DESCRIPTION
       Prtraceroute works just as the original traceroute with the addition of
       routing policy analysis as provided by the Internet Routing Registery
       (IRR).  Prtraceroute will record the series of gateways traversed by
       packets from the originating host to the destination host, including
       policy analysis for each hop.

       Routing in the Internet is a two level hiearchy.  The highest level of
       routing is performed between Autonomous Systems (AS), typically using the
       Border Gateway Protocol (BGP).  The second level of routing occurs within
       each AS and is administered independently by each AS.  The routing
       policies, as registered in the IRR indicate the policies that each AS
       uses to communicate with all of it's peer ASs.  Prtraceroute will display
       the route actually taken and how that route compares with the information
       maintained in the IRR.

       prtraceroute ignores error and warning messages due to communication to
       the database server or parsing policy objects.  Please see -ignore_errors
       and -report_errors options below.

IRRToolSet COMMON OPTIONS
       -help  Print summary of command-line options and abort.

       -T [whois_query | whois_response | input | all]
              Trace the argument. Useful for debugging.

       -D <integer>
              Print debugging messages of debug channel <integer> (if compiled
              with DEBUG defined).

       -version
              Print the version number and quit.

       -h <host-name>
              Establish a whois connection to host <host-name>.  The default is
              whois.radb.net.

       -p <port-no>
              Establish a whois connection to port <port-no>.  The default is
              43.

       -rusage
              Print resource usage upon completion.

       -ignore_errors
              Do not print error and warning messages due to communication to
              the database server or parsing policy objects.

       -report_errors
              Print error and warning messages due to communication to the
              database server or parsing policy objects.

       -protocol <protocol>
              Use the <protocol> to connect to the IRR server. <protocol> can be
              irrd(rawhoisd), ripe(bird), and ripe_perl. The default is irrd.
              The ripe_perl option should be used with the old ripe server.

       -s <source-list>
              Consider the sources specified in the comma separated <source-
              list>.  If an object is defined in multiple sources in <source-
              list>, pmatch uses the definition first encountered in <source-
              list> from left to right.

ENVIRONMENT VARIABLES
              IRR_HOST
                     Specifies the IRR host to connect.

              IRR_PORT
                     Specifies the IRR port number to connect.

              IRR_SOURCES
                     Specifies the source list (comma separated) to consider.

       Command line options take precedence over environment variables.

OTHER OPTIONS
              -m n Set the max time-to-live (max number of hops) used in
                   outgoing probe packets.  The default is 30 hops (the same
                   default used for TCP connections).

              -n   Print hop addresses numerically rather than symbolically and
                   numerically (saves a nameserver address-to-name lookup for
                   each gateway found on the path).

              -p n Set the base UDP port number used in probes (default is
                   33434).  Traceroute hopes that nothing is listening on UDP
                   ports base to base+nhops-1 at the destination host (so an
                   ICMP PORT_UNREACHABLE message will be returned to terminate
                   the route tracing).  If something is listening on a port in
                   the default range, this option can be used to pick an unused
                   port range.

              -r   Bypass the normal routing tables and send directly to a host
                   on an attached network.  If the host is not on a directly-
                   attached network, an error is returned.  This option can be
                   used to ping a local host through an interface that has no
                   route through it (e.g., after the interface was dropped by
                   routed(8C)).

              -s addr
                   Use addr as the IP address (which must be given as an IP
                   number, not a hostname) as the source address in outgoing
                   probe packets.  On hosts with more than one IP address, this
                   option can be used to force the source address to be
                   something other than the IP address of the interface the
                   probe packet is sent on.  If the IP address is not one of
                   this machine's interface addresses, an error is returned and
                   nothing is sent.

              -s addr Use addr as the IP address (which must be given as an IP
                      number, not a hostname) as the source address in outgoing
                      probe packets.  On hosts with more than one IP address,
                      this option can be used to force the source address to be
                      something other than the IP address of the interface the
                      probe packet is sent on.  If the IP address is not one of
                      this machine's interface addresses, an error is returned
                      and nothing is sent.

              -g addr Enable the IP LSRR (Loose Source Record Route) option in
                      addition to the TTL tests.  This is useful for asking how
                      somebody else, at IP address addr, reaches a particular
                      target.

              -t tos  Set the type-of-service in probe packets to the following
                      value (default zero).  The value must be a decimal integer
                      in the range 0 to 255.  This option can be used to see if
                      different types-of-service result in different paths.  (If
                      you are not running 4.4bsd, this may be academic since the
                      normal network services like telnet and ftp don't let you
                      control the TOS).  Not all values of TOS are legal or
                      meaningful - see the IP spec for definitions.  Useful
                      values are probably `-t 16' (low delay) and `-t 8' (high
                      throughput).

              -v   Verbose output.  Received ICMP packets other than
                   TIME_EXCEEDED and UNREACHABLEs are listed.

              -w n Set the time to wait for a response to a probe to n seconds
                   (default 3 sec.).

              This program attempts to trace the route an IP packet would follow
              to some internet host by launching UDP probe packets with a small
              ttl (time to live) then listening for an ICMP "time exceeded"
              reply from a gateway.  We start our probes with a ttl of one and
              increase by one until we get an ICMP "port unreachable" (which
              means we got to "host") or hit a max (which defaults to 30 hops &
              can be changed with the -m flag).  Three probes (change with -q
              flag) are sent at each ttl setting and a line is printed showing
              the ttl, address of the gateway and round trip time of each probe.
              If the probe answers come from different gateways, the address of
              each responding system will be printed.  If there is no response
              within a 3 sec. timeout interval (changed with the -w flag), a "*"
              is printed for that probe.

              We don't want the destination host to process the UDP probe
              packets so the destination port is set to an unlikely value (if
              some clod on the destination is using that value, it can be
              changed with the -p flag).

              A sample use and output might be:

                     [yak 71]% traceroute nis.nsf.net.
                     traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
                      1  helios.ee.lbl.gov (128.3.112.1)  19 ms  19 ms  0 ms
                      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
                      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
                      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  39 ms
                      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  39 ms  39 ms  39 ms
                      6  128.32.197.4 (128.32.197.4)  40 ms  59 ms  59 ms
                      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  59 ms
                      8  129.140.70.13 (129.140.70.13)  99 ms  99 ms  80 ms
                      9  129.140.71.6 (129.140.71.6)  139 ms  239 ms  319 ms
                     10  129.140.81.7 (129.140.81.7)  220 ms  199 ms  199 ms
                     11  nic.merit.edu (35.1.1.48)  239 ms  239 ms  239 ms

              Note that lines 2 & 3 are the same.  This is due to a buggy kernel
              on the 2nd hop system - lbl-csam.arpa - that forwards packets with
              a zero ttl (a bug in the distributed version of 4.3BSD).

              A more interesting example is:

                     [yak 72]% traceroute allspice.lcs.mit.edu.
                     traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
                      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
                      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  19 ms  19 ms
                      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  19 ms
                      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  19 ms  39 ms  39 ms
                      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  20 ms  39 ms  39 ms
                      6  128.32.197.4 (128.32.197.4)  59 ms  119 ms  39 ms
                      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  39 ms
                      8  129.140.70.13 (129.140.70.13)  80 ms  79 ms  99 ms
                      9  129.140.71.6 (129.140.71.6)  139 ms  139 ms  159 ms
                     10  129.140.81.7 (129.140.81.7)  199 ms  180 ms  300 ms
                     11  129.140.72.17 (129.140.72.17)  300 ms  239 ms  239 ms
                     12  * * *
                     13  128.121.54.72 (128.121.54.72)  259 ms  499 ms  279 ms
                     14  * * *
                     15  * * *
                     16  * * *
                     17  * * *
                     18  ALLSPICE.LCS.MIT.EDU (18.26.0.115)  339 ms  279 ms  279 ms

              Note that the gateways 12, 14, 15, 16 & 17 hops away either don't
              send ICMP "time exceeded" messages or send them with a ttl too
              small to reach us.  14 - 17 are running the MIT C Gateway code
              that doesn't send "time exceeded"s.  God only knows what's going
              on with 12.

              The silent gateway 12 in the above may be the result of a bug in
              the 4.[23]BSD network code (and its derivatives):  4.x (x <= 3)
              sends an unreachable message using whatever ttl remains in the
              original datagram.  Since, for gateways, the remaining ttl is
              zero, the ICMP "time exceeded" is guaranteed to not make it back
              to us.  The behavior of this bug is slightly more interesting when
              it appears on the destination system:

                      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
                      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  39 ms
                      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  39 ms  19 ms
                      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  19 ms
                      5  ccn-nerif35.Berkeley.EDU (128.32.168.35)  39 ms  39 ms  39 ms
                      6  csgw.Berkeley.EDU (128.32.133.254)  39 ms  59 ms  39 ms
                      7  * * *
                      8  * * *
                      9  * * *
                     10  * * *
                     11  * * *
                     12  * * *
                     13  rip.Berkeley.EDU (128.32.131.22)  59 ms !  39 ms !  39 ms !

              Notice that there are 12 "gateways" (13 is the final destination)
              and exactly the last half of them are "missing".  What's really
              happening is that rip (a Sun-3 running Sun OS3.5) is using the ttl
              from our arriving datagram as the ttl in its ICMP reply.  So, the
              reply will time out on the return path (with no notice sent to
              anyone since ICMP's aren't sent for ICMP's) until we probe with a
              ttl that's at least twice the path length.  I.e., rip is really
              only 7 hops away.  A reply that returns with a ttl of 1 is a clue
              this problem exists.  Traceroute prints a "!" after the time if
              the ttl is <= 1.  Since vendors ship a lot of obsolete (DEC's
              Ultrix, Sun 3.x) or non-standard (HPUX) software, expect to see
              this problem frequently and/or take care picking the target host
              of your probes.

              Other possible annotations after the time are !H, !N, !P (got a
              host, network or protocol unreachable, respectively),
              !S or !F (source route failed or fragmentation needed - neither of
              these should ever occur and the associated gateway is busted if
              you see one).  If almost all the probes result in some kind of
              unreachable, traceroute will give up and exit.

                     traceroute -g 10.3.0.5 128.182.0.0

              will show the path from the Cambridge Mailbridge to PSC while

                     traceroute -g 192.5.146.4 -g 10.3.0.5 35.0.0.0

              shows how the Cambridge Mailbrige reaches Merit, by using PSC to
              reach the Mailbridge.

              This program is intended for use in network testing, measurement
              and management.  It should be used primarily for manual fault
              isolation.  Because of the load it could impose on the network, it
              is unwise to use traceroute during normal operations or from
              automated scripts.


POLICY EXAMPLE
       An example run could produce the following output.
              [1335] kit.isi.edu > prtraceroute ftp.ripe.net
              prtraceroute to ftp.ripe.net (193.0.0.195), 30 hops max, 12 byte packets
               1  [AS226] cisco2-160.isi.edu (128.9.160.2)  9.531 ms  9.755 ms  8.841 ms
               2  [AS226] ln-gw32.isi.edu (128.9.32.1)  124.38 ms  15.269 ms  17.034 ms
               3  [AS226] 130.152.168.1 (130.152.168.1)  16.77 ms  10.429 ms  10.187 ms
               4  [AS2150] SWRL-ISI-GW.LN.NET (204.102.78.2)  63.025 ms  193.177 ms  17.107 ms
               5  [AS3561] border1-hssi1-0.Bloomington.mci.net (204.70.48.5)  16.474 ms  15.876 ms  15.211 ms
               6  [AS3561] core1-fddi-0.Bloomington.mci.net (204.70.2.129)  53.068 ms  215.841 ms  40.662 ms
               7  [AS3561] core1.Washington.mci.net (204.70.4.129)  79.217 ms  84.029 ms  82.851 ms
               8  [AS3561] core1-hssi-3.NewYork.mci.net (204.70.1.6)  85.65 ms  85.414 ms  84.62 ms
               9  [AS3561] 204.70.2.30 (204.70.2.30)  84.562 ms  85.313 ms  85.524 ms
              10  [AS3561] surfnet.NewYork.mci.net (204.189.136.154)  186.696 ms  194.363 ms  184.965 ms
              11  [AS1103] Amsterdam2.router.surfnet.nl (145.41.6.66)  195.545 ms  195.767 ms  187.228 ms
              12  [AS1200] Amsterdam.ripe.net (193.148.15.68)  193.955 ms  196.1 ms  182.065 ms
              13  [AS3333] info.ripe.net (193.0.0.195)  211.185 ms  265.305 ms  278.876 ms

              Path taken: AS226 AS2150 AS3561 AS1103 AS1200 AS3333

               13   AS3333 info.ripe.net                     destination -> !as-out
               12   AS1200 Amsterdam.ripe.net                     !as-in -> as-out
               11   AS1103 Amsterdam2.router.surfnet.nl           !as-in -> as-out
               10   AS3561 surfnet.NewYork.mci.net              as-in: 1 -> internal
                9   AS3561 204.70.2.30                          internal -> internal
                8   AS3561 core1-hssi-3.NewYork.mci.net         internal -> internal
                7   AS3561 core1.Washington.mci.net             internal -> internal
                6   AS3561 core1-fddi-0.Bloomington.mci.net     internal -> internal
                5   AS3561 border1-hssi1-0.Bloomington.mci.net  internal -> as-out
                4   AS2150 SWRL-ISI-GW.LN.NET                     !as-in -> !as-out
                3    AS226 130.152.168.1                          !as-in -> internal
                2    AS226 ln-gw32.isi.edu                      internal -> internal
                1    AS226 cisco2-160.isi.edu                   internal -> internal
                0    AS226 kit.isi.edu                          internal -> source


       The first group of lines (1-13) are similiar to the output of traceroute
       with one addition, the AS number is included in square brackets, for
       example cisco2-160.isi.edu is in AS226.

       The second part of the output:

              Path taken: AS226 AS2150 AS3561 AS1103 AS1200 AS3333


       simply lists the ASs traversed by this route.


       The third part of the output provides the policy analysis as registered
       in  the IRR.   Notice that the output is provided in reverse order, or
       destination first until the source.  This reflects the manner in which
       routes are advertised and propagated in the Internet.  In other words,
       AS3333 announces the prefix "193.0.0.0/24" which "info.ripe.net
       (193.0.0.195)" belongs.  AS1200, accepts the prefix and in turn announces
       it according to it's as-out policies and so on.  As an example, the first
       three fields are

        10  AS3561 surfnet.NewYork.mci.net   as-in: 1 -> internal

       The TTL, AS and Gateway fields are the same as we have seen.  The 'as-in:
       1 - internal' part of the above output describes the routing policy
       registered in the IRR.  The first field 'as-in: 1' is the import field
       and the 'internal' is the export field.  In this example, 'as-in: 1' in
       the import field means that the prefix was accepted via an as-in policy
       and the 1 indicates that it was the highest preference (a 2 would
       indicate the second most prefered, etc.)  The export field contains
       'internal', meaning the next hop is in the same AS as the current hop.
       Following is a list of possible values that can be present in the import
       field:


       Destination
              Current hop is the destination host.

       Internal
              The current hop and next hop (TTL+1) belong to the same AS.

       as-in: 1
              The prefix announcement from the next hop AS (TTL+1) was the first
              preferred hop from the current AS to the destination prefix.  A
              value of 2 would indicate that the next hop was the second
              preferred route according to the current hop, and so on.

       default: 1
              TTL+1 was the first preferred default route.  A value of 2 would
              indicate that the next hop was the second prefeered default, etc.

       !as-in The current AS has no registered as-in or default policy to accept
              prefixes being exported from the next hop (TTL+1).



       The following list describes the possible values that can be provided in
       the export field of the analysis portion of the output.

       Source This host is the source of the execution

       Internel
              The current hop is the same AS as previous hop (TTL-1).

       as-out This indicates that the current AS announces the prefix to the
              previous AS.

       !as-out
              This indicates that the current AS has no policy to announce the
              prefix to the previous hop.

       From our example above,

               13   AS3333 info.ripe.net                       destination - !as-out
               12   AS1200 Amsterdam.ripe.net                      !as-in - as-out
               11   AS1103 Amsterdam2.router.surfnet.nl            !as-in - as-out
               10   AS3561 surfnet.NewYork.mci.net               as-in: 1 - internal
                9   AS3561 204.70.2.30                           internal - internal

       we can conclude: That info.ripe.net was the destination host and is part
       of AS3333.  AS3333 provides no as-out policy announcing prefix
       193.0.0.0/24 to AS1200 and AS1200 provides no as-in policy accepting
       prefix 193.0.0.0/24 from AS3333.  This flags a two way policy
       inconsistency between AS3333 and AS1200.  AS1200 announces to AS1103 and
       AS1103 has no policy to accept the prefix from AS1200.  This indicates
       incomplete policy information for AS1103 on behalf of AS1200.  AS1103
       announces to AS3561 and that AS3561 uses AS1103 as it's most preferred
       route for the prefix in question.  This is the only policy that is
       complete by both ASs in this example.  Finally the hop between
       surfnet.NewYork.mci.net and 204.70.2.30 is internel since both gateways
       belong to AS361.

AUTHOR
       The original traceroute was implemented by Van Jacobson from a suggestion
       by Steve Deering.  Debugged by a cast of thousands with particularly
       cogent suggestions or fixes from C. Philip Wood, Tim Seaver and Ken
       Adelman.  The code was then mangled into C++ and the Routing Policy
       support was added for this version of prtraceroute.

SEE ALSO
       netstat(1), ping(8), prpath(1) peval(1)







4.3 Berkeley Distribution        April 29, 1996                  PRTRACEROUTE(8)