Este es el archivo de ayuda del comando traceroute en Linux.

Obtenido, haciendo: man traceroute > traceroute_help.txt


TRACEROUTE(1)                                               Traceroute For Linux                                              TRACEROUTE(1)

NAME
       traceroute - print the route packets trace to network host

SYNOPSIS
       traceroute [-46dFITUnreAV] [-f first_ttl] [-g gate,...]
               [-i device] [-m max_ttl] [-p port] [-s src_addr]
               [-q nqueries] [-N squeries] [-t tos]
               [-l flow_label] [-w waittimes] [-z sendwait] [-UL] [-D]
               [-P proto] [--sport=port] [-M method] [-O mod_options]
               [--mtu] [--back]
               host [packet_len]
       traceroute6  [options]
       tcptraceroute  [options]
       lft  [options]

DESCRIPTION
       traceroute  tracks  the  route  packets taken from an IP network on their way to a given host. It utilizes the IP protocol's time to
       live (TTL) field and attempts to elicit an ICMP TIME_EXCEEDED response from each gateway along the path to the host.

       traceroute6 is equivalent to traceroute -6

       tcptraceroute is equivalent to traceroute -T

       lft , the Layer Four Traceroute, performs a TCP traceroute, like traceroute -T , but attempts  to  provide  compatibility  with  the
       original such implementation, also called "lft".

       The  only  required  parameter is the name or IP address of the destination host .  The optional packet_len`gth is the total size of
       the probing packet (default 60 bytes for IPv4 and 80 for IPv6). The specified size can be ignored in some situations or increased up
       to a minimal value.

       This program attempts to trace the route an IP packet would follow to some internet host by launching 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" (or TCP reset), which means we got to the "host", or hit a max (which defaults to 30
       hops). Three probes (by default) 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. The address can be followed by additional information when requested. If the probe answers come from
       different gateways, the address of each responding system will be printed.  If there is no response within a certain timeout, an "*"
       (asterisk) is printed for that probe.

       After  the  trip  time, some additional annotation can be printed: !H, !N, or !P (host, network or protocol unreachable), !S (source
       route failed), !F (fragmentation needed), !X (communication administratively prohibited), !V (host precedence violation), !C (prece‐
       dence  cutoff  in  effect),  or  !<num> (ICMP unreachable code <num>).  If almost all the probes result in some kind of unreachable,
       traceroute will give up and exit.

       We don't want the destination host to process the UDP probe packets, so the destination port is set to an unlikely  value  (you  can
       change it with the -p flag). There is no such a problem for ICMP or TCP tracerouting (for TCP we use half-open technique, which pre‐
       vents our probes to be seen by applications on the destination host).

       In the modern network environment the traditional traceroute methods can not be always applicable,  because  of  widespread  use  of
       firewalls.   Such firewalls filter the "unlikely" UDP ports, or even ICMP echoes.  To solve this, some additional tracerouting meth‐
       ods are implemented (including tcp), see LIST OF  AVAILABLE  METHODS  below.  Such  methods  try  to  use  particular  protocol  and
       source/destination  port,  in  order  to bypass firewalls (to be seen by firewalls just as a start of allowed type of a network ses‐
       sion).

OPTIONS
       --help Print help info and exit.

       -4, -6 Explicitly force IPv4 or IPv6 tracerouting. By default, the program will try to resolve the name given, and choose the appro‐
              priate protocol automatically. If resolving a host name returns both IPv4 and IPv6 addresses, traceroute will use IPv4.

       -I, --icmp
              Use ICMP ECHO for probes

       -T, --tcp
              Use TCP SYN for probes

       -d, --debug
              Enable socket level debugging (when the Linux kernel supports it)

       -F, --dont-fragment
              Do  not  fragment  probe packets. (For IPv4 it also sets DF bit, which tells intermediate routers not to fragment remotely as
              well).

              Varying the size of the probing packet by the packet_len command line parameter, you can manually  obtain  information  about
              the MTU of individual network hops. The --mtu option (see below) tries to do this automatically.

              Note, that non-fragmented features (like -F or --mtu) work properly since the Linux kernel 2.6.22 only.  Before that version,
              IPv6 was always fragmented, IPv4 could use the once the discovered final mtu only (from the route cache), which can  be  less
              than the actual mtu of a device.

       -f first_ttl, --first=first_ttl
              Specifies with what TTL to start. Defaults to 1.

       -g gateway, --gateway=gateway
              Tells traceroute to add an IP source routing option to the outgoing packet that tells the network to route the packet through
              the specified gateway (most routers have disabled source routing for security reasons).  In general, several gateway's is al‐
              lowed  (comma  separated).  For  IPv6, the form of num,addr,addr...  is allowed, where num is a route header type (default is
              type 2). Note the type 0 route header is now deprecated (rfc5095).

       -i interface, --interface=interface
              Specifies the interface through which traceroute should send packets. By default, the interface is selected according to  the
              routing table.

       -m max_ttl, --max-hops=max_ttl
              Specifies the maximum number of hops (max time-to-live value) traceroute will probe. The default is 30.

       -N squeries, --sim-queries=squeries
              Specifies  the  number of probe packets sent out simultaneously.  Sending several probes concurrently can speed up traceroute
              considerably. The default value is 16.
              Note that some routers and hosts can use ICMP rate throttling. In such a situation specifying too large number  can  lead  to
              loss of some responses.

       -n     Do not try to map IP addresses to host names when displaying them.

       -p port, --port=port
              For  UDP tracing, specifies the destination port base traceroute will use (the destination port number will be incremented by
              each probe).
              For ICMP tracing, specifies the initial ICMP sequence value (incremented by each probe too).
              For TCP and others specifies just the (constant) destination port to connect. When using the tcptraceroute wrapper, -p speci‐
              fies the source port.

       -t tos, --tos=tos
              For  IPv4, set the Type of Service (TOS) and Precedence value. Useful values are 16 (low delay) and 8 (high throughput). Note
              that in order to use some TOS precedence values, you have to be super user.
              For IPv6, set the Traffic Control value.

       -l flow_label, --flowlabel=flow_label
              Use specified flow_label for IPv6 packets.

       -w max[,here,near], --wait=max[,here,near]
              Determines how long to wait for a response to a probe.

              There are three (in general) float values separated by a comma (or a slash).  Max specifies the maximum time (in seconds, de‐
              fault 5.0) to wait, in any case.

              Traditional traceroute implementation always waited whole max seconds for any probe. But if we already have some replies from
              the same hop, or even from some next hop, we can use the round trip time of such a reply as a hint to  determine  the  actual
              reasonable amount of time to wait.

              The  optional  here (default 3.0) specifies a factor to multiply the round trip time of an already received response from the
              same hop. The resulting value is used as a timeout for the probe, instead of (but no more than) max.  The optional near  (de‐
              fault  10.0)  specifies  a  similar factor for a response from some next hop.  (The time of the first found result is used in
              both cases).

              First, we look for the same hop (of the probe which will be printed first from now).  If nothing found, then  look  for  some
              next hop. If nothing found, use max.  If here and/or near have zero values, the corresponding computation is skipped.
              Here and near are always set to zero if only max is specified (for compatibility with previous versions).

       -q nqueries, --queries=nqueries
              Sets the number of probe packets per hop. The default is 3.

       -r     Bypass  the  normal  routing tables and send directly to a host on an attached network.  If the host is not on a directly-at‐
              tached network, an error is returned.  This option can be used to ping a local host through an interface that  has  no  route
              through it.

       -s source_addr, --source=source_addr
              Chooses  an  alternative source address. Note that you must select the address of one of the interfaces.  By default, the ad‐
              dress of the outgoing interface is used.

       -z sendwait, --sendwait=sendwait
              Minimal time interval between probes (default 0).  If the value is more than 10, then it specifies a number in  milliseconds,
              else it is a number of seconds (float point values allowed too).  Useful when some routers use rate-limit for ICMP messages.

       -e, --extensions
              Show  ICMP extensions (rfc4884). The general form is CLASS/TYPE: followed by a hexadecimal dump.  The MPLS (rfc4950) is shown
              parsed, in a form: MPLS:L=label,E=exp_use,S=stack_bottom,T=TTL (more objects separated by / ).

       -A, --as-path-lookups
              Perform AS path lookups in routing registries and print results directly after the corresponding addresses.

       -V, --version
              Print the version and exit.

       There are additional options intended for advanced usage (such as alternate trace methods etc.):

       --sport=port
              Chooses the source port to use. Implies -N 1 -w 5 .  Normally source ports (if applicable) are chosen by the system.

       --fwmark=mark
              Set the firewall mark for outgoing packets (since the Linux kernel 2.6.25).

       -M method, --module=name
              Use specified method for traceroute operations. Default traditional udp method has name default, icmp (-I) and tcp (-T)  have
              names icmp and tcp respectively.
              Method-specific options can be passed by -O .  Most methods have their simple shortcuts, (-I means -M icmp, etc).

       -O option, --options=options
              Specifies  some  method-specific  option. Several options are separated by comma (or use several -O on cmdline).  Each method
              may have its own specific options, or many not have them at all.  To print information about available options, use -O help.

       -U, --udp
              Use UDP to particular destination port for tracerouting (instead of increasing the port per each probe). Default port  is  53
              (dns).

       -UL    Use UDPLITE for tracerouting (default port is 53).

       -D, --dccp
              Use DCCP Requests for probes.

       -P protocol, --protocol=protocol
              Use raw packet of specified protocol for tracerouting. Default protocol is 253 (rfc3692).

       --mtu  Discover  MTU along the path being traced. Implies -F -N 1.  New mtu is printed once in a form of F=NUM at the first probe of
              a hop which requires such mtu to be reached. (Actually, the correspond "frag needed" icmp message normally  is  sent  by  the
              previous hop).

              Note,  that  some routers might cache once the seen information on a fragmentation. Thus you can receive the final mtu from a
              closer hop.  Try to specify an unusual tos by -t , this can help for one attempt (then it can be cached there as well).
              See -F option for more info.

       --back Print the number of backward hops when it seems different with the forward direction. This number is  guessed  in  assumption
              that  remote  hops send reply packets with initial ttl set to either 64, or 128 or 255 (which seems a common practice). It is
              printed as a negate value in a form of '-NUM' .

LIST OF AVAILABLE METHODS
       In general, a particular traceroute method may have to be chosen by -M name, but most of  the  methods  have  their  simple  cmdline
       switches (you can see them after the method name, if present).

   default
       The traditional, ancient method of tracerouting. Used by default.

       Probe  packets are udp datagrams with so-called "unlikely" destination ports.  The "unlikely" port of the first probe is 33434, then
       for each next probe it is incremented by one. Since the ports are expected to be unused, the destination host normally returns "icmp
       unreach port" as a final response.  (Nobody knows what happens when some application listens for such ports, though).

       This method is allowed for unprivileged users.

   icmp       -I
       Most usual method for now, which uses icmp echo packets for probes.
       If you can ping(8) the destination host, icmp tracerouting is applicable as well.

       This  method  may  be allowed for unprivileged users since the kernel 3.0 (IPv4, for IPv6 since 3.11), which supports new dgram icmp
       (or "ping") sockets. To allow such sockets, sysadmin should provide net/ipv4/ping_group_range sysctl range to match any group of the
       user.
       Options:

       raw    Use only raw sockets (the traditional way).
              This way is tried first by default (for compatibility reasons), then new dgram icmp sockets as fallback.

       dgram  Use only dgram icmp sockets.

   tcp        -T
       Well-known modern method, intended to bypass firewalls.
       Uses the constant destination port (default is 80, http).

       If  some  filters  are present in the network path, then most probably any "unlikely" udp ports (as for default method) or even icmp
       echoes (as for icmp) are filtered, and whole tracerouting will just stop at such a firewall.  To bypass a network filter, we have to
       use  only  allowed  protocol/port  combinations. If we trace for some, say, mailserver, then more likely -T -p 25 can reach it, even
       when -I can not.

       This method uses well-known "half-open technique", which prevents applications on the destination host from  seeing  our  probes  at
       all.   Normally,  a tcp syn is sent. For non-listened ports we receive tcp reset, and all is done. For active listening ports we re‐
       ceive tcp syn+ack, but answer by tcp reset (instead of expected tcp ack), this way the remote tcp session is  dropped  even  without
       the application ever taking notice.

       There is a couple of options for tcp method:

       syn,ack,fin,rst,psh,urg,ece,cwr
              Sets specified tcp flags for probe packet, in any combination.

       flags=num
              Sets the flags field in the tcp header exactly to num.

       ecn    Send syn packet with tcp flags ECE and CWR (for Explicit Congestion Notification, rfc3168).

       sack,timestamps,window_scaling
              Use the corresponding tcp header option in the outgoing probe packet.

       sysctl Use  current  sysctl  (/proc/sys/net/*)  setting for the tcp header options above and ecn.  Always set by default, if nothing
              else specified.

       mss=num
              Use value of num for maxseg tcp header option (when syn).

       info   Print tcp flags of final tcp replies when the target host is reached.  Allows to determine whether an application listens the
              port and other useful things.

       Default options is syn,sysctl.

   tcpconn
       An initial implementation of tcp method, simple using connect(2) call, which does full tcp session opening. Not recommended for nor‐
       mal use, because a destination application is always affected (and can be confused).

   udp        -U
       Use udp datagram with constant destination port (default 53, dns).
       Intended to bypass firewall as well.

       Note, that unlike in tcp method, the correspond application on the destination host always receive our probes  (with  random  data),
       and most can easily be confused by them. Most cases it will not respond to our packets though, so we will never see the final hop in
       the trace. (Fortunately, it seems that at least dns servers replies with something angry).

       This method is allowed for unprivileged users.

   udplite    -UL
       Use udplite datagram for probes (with constant destination port, default 53).

       This method is allowed for unprivileged users.
       Options:

       coverage=num
              Set udplite send coverage to num.

   dccp    -D
       Use DCCP Request packets for probes (rfc4340).

       This method uses the same "half-open technique" as used for TCP.  The default destination port is 33434.

       Options:

       service=num
              Set DCCP service code to num (default is 1885957735).

   raw        -P proto
       Send raw packet of protocol proto.
       No protocol-specific headers are used, just IP header only.
       Implies -N 1 -w 5 .
       Options:

       protocol=proto
              Use IP protocol proto (default 253).

NOTES
       To speed up work, normally several probes are sent simultaneously.  On the other hand, it creates a "storm of packages",  especially
       in  the  reply  direction. Routers can throttle the rate of icmp responses, and some of replies can be lost. To avoid this, decrease
       the number of simultaneous probes, or even set it to 1 (like in initial traceroute implementation), i.e.  -N 1

       The final (target) host can drop some of the simultaneous probes, and might even answer only the latest ones. It can lead  to  extra
       "looks  like  expired"  hops  near the final hop. We use a smart algorithm to auto-detect such a situation, but if it cannot help in
       your case, just use -N 1 too.

       For even greater stability you can slow down the program's work by -z option, for example use -z 0.5 for half-second  pause  between
       probes.

       To  avoid  an  extra  waiting, we use adaptive algorithm for timeouts (see -w option for more info). It can lead to premature expiry
       (especially when response times differ at times) and printing "*" instead of a time. In such a case, switch this algorithm  off,  by
       specifying -w with the desired timeout only (for example, -w 5).

       If some hops report nothing for every method, the last chance to obtain something is to use ping -R command (IPv4, and for nearest 8
       hops only).

SEE ALSO
       ping(8), ping6(8), tcpdump(8), netstat(8)

Traceroute                                                    11 October 2006                                                 TRACEROUTE(1)

Last modified: Wednesday, 17 August 2022, 9:42 AM