распечатать трассировку пакетов маршрута к сетевому узлу (print the route packets trace to network host)
Описание (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
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
(precedence 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 prevents 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
methods 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
session).
