Provided by: ndisc6_1.0.7-1ubuntu2_amd64 
NAME
rltraceroute6 - IPv6 traceroute tool
tcptraceroute6 - TCP/IPv6 traceroute tool
SYNOPSIS
traceroute6 [-AdEILlnrSU] [-f min_hop] [-g hop] [ -i iface] [-m max_hop] [-p port] [-q attempts] [ -s
source] [-t tclass] [-w wait] [-z delay_ms] < hostname/address> [packet length]
tcptraceroute6 [-AdEnrS] [-f min_hop] [-g hop] [ -i iface] [-l packet_size] [-m max_hop] [-p port] [ -q
attempts] [-s source] [-t tclass] [-w wait] [ -z delay_ms] < hostname/address> [port]
DESCRIPTON
rltraceroute6 is an IPv6 traceroute implementation.
It displays the list of hops along the network route between the local system and specified destination,
by sending packets while incrementing their hop limit, until the final destination is reached.
By default, rltraceroute6 sends UDP probe packets toward the destination (that's the historical default).
However, it can also send TCP packets, much like Michael C. Toren's tcptraceroute does on IPv4 networks;
tcptraceroute6 sends TCP packets by default (and mimics tcptraceroute command line syntax). Finally, it
can also send ICMPv6 Echo Request packets, like some other traceroute implementations (such as the one in
Microsoft Windows); tracert6 does this by default.
You must specify the name or address of the host toward which the network route should be determined. An
optional additional parameter specifies either the probe packets length (for UDP and ICMP packets), or
the destination port number/service name (for TCP packets).
Note that TCP destination port zero really is TCP port numbered 0 (which cannot be used via the standard
higer-level TCP/IP programming interface).
OPTIONS
-A Send TCP/ACK probe packets. That's very efficient against stateless firewalls (e.g. the official
Linux kernel versions up to and including 2.4.31 and 2.6.14), and utterly helpless against
stateful ones. Note that TCP/ACK probing cannot determine whether the destination TCP port is open
or not.
-d Enable socket debugging option (SO_DEBUG). Unless you are debugging the kernel, this is probably
not going to have any actual effect.
-E Send ECN-setup TCP/SYN probe packets (as per RFC 3168) rather than non-ECN-setup TCP/SYN probe
packets. This has no effect unless command line optin -S is specified as well.
-F This option is ignored for backward compatibility. IPv6 packets are never fragmented en route.
-f Override the initial IPv6 packets hop limit (default: 1).
-g Add an IPv6 route segment within an IPv6 Routing Header. This enables loose source routing.
Currently, only "Type 0" routing header is supported.
-h Display some help and exit.
-I (rltraceroute6 only)
Send ICMPv6 Echo requests (like ping6) as probe packets. That's the default for tracert6.
-i Only send packets through the specified interface. See also BUGS.
-I (rltraceroute6 only)
Send UDP-Lite (protocol 136) packets (with full checksum coverage) as probe packets instead of
normal UDP (protocol 17).
-l (rltraceroute6 only)
Print the hop limit of received packets. This is mostly used to detect asymmetric routing.
-l (tcptraceroute6 only)
Specify the size (bytes) of sent packets.
-m Override the maximum hop limit (maximum number of hops). The default is 30 hops which should be
sufficient on the IPv6 Internet for some time.
-N Try to resolve each hop's IPv6 address to a host name. This is the default. This option is meant
for backward compatibility with tcptraceroute(8).
-n Do not try to resolve each hop's IPv6 address to a host name. That may speed up the traceroute
significantly.
-p For rltraceroute6, specify the base destination port number (default: 33434). rltraceroute6
assumes that packets toward this port up to this port plus the maximum hop limit are not in use by
any program on the final destination and that they are not blocked by some firewall. The fact that
this very assumption was not always correct, eventually lead to the development of the original
IPv4 tcptraceroute by Michael Toren.
For tcptraceroute6, specify the source port number (default: auto). Note that source port number
zero really means number zero, rather than some port number that would be automatically assigned,
as is the case with usual softwares.
-q Override the number of probes sent to each hop (default: 3).
-r Do not route packets, i.e. do not send packets through a gateway that would be specified by the
routing table. See also BUGS.
-S Use TCP/SYN probe packets. That's the default for tcptraceroute6.
-s Specify the source address to use for probe packets explicitly.
-S Use UDP probe packets. That's the default for rltraceroute6.
-t Specify the traffic class (DSCP) for probe packets. See also BUGS.
-U (rltraceroute6 only)
Send UDP probe packets. That's the default.
-V Display program version and license and exit.
-w Override the delay (in seconds) to wait for response once a given probe packet was sent (default:
5 seconds).
-x This option is ignored for seamless migration from IPv4 traceroute. The IPv6 header has no
checksum field.
-z Specify a milliseconds delay to wait between each probe with identical hop limit. This can be
useful to work-around ICMPv6 rate limitation on some hosts.
DIAGNOSTICS
If a response is received, the round-trip time is printed. In addition, specific symbols denote certain
errors:
* No response
No valid response received before the timeout delay (see -w option).
!N No route to destination
There is no entry for the destination network in the routing table.
!A Communication with destination administratively prohibited
A firewall explicitly rejected the traffic.
!S Beyond scope of source address
The address scope of the source address is too small to reach the destination address. At the time
of writing, this can only happen when using a link-local source address to reach a global scope
destination. (Note: some IPv4 traceroute implementations use !S for source route error which is
completely different)
!H Address unreachable
The host address is not reachable for some other reasons, particularly a link-layer failure (e.g.
Neighbor discovery failure).
!P Unrecognized Next Header type encountered
The destination does not implement the layer-4 protocol used. You should retry with ICMPv6 Echo
Requests (-I command line option) which MUST be supported by any IPv6 node.
SECURITY
rltraceroute6 should be setuid root to allow use by non privileged users. It will drop its root
privileges before any attempt is made to send or receive data from the network so as to reduce the
possible impact of a security vulnerability.
BUGS
However useful they might be, -i and -r options are ignored by the official Linux kernel at the time of
writing this manpage, and hence do not work as documented.
Support for option -t was broken until Linux kernel version 2.6.18.
Usage of Routing Header, with option -g, triggers an OOPS on Linux kernel versions below 2.6.17.12.
Receiving TCP/SYN-ACK packets does not work on FreeBSD at all. This severely limits the usefulness of
tcptraceroute6 on FreeBSD.
Packet length takes the IPv6 header and, if present, extension headers into account. rltraceroute6
versions before 0.7.4 used it as IPv6 payload length instead, i.e. did not include the layer-3 headers in
the computation. Linux iputils traceroute6 does not even include the UDP header. On the whole, the
packet length semantic is very inconsistent among IPv6 traceroute implementations.
SEE ALSO
ipv6(7), traceroute(8), tcptraceroute(8), traceroute6(8)
AUTHOR
Rémi Denis-Courmont <remi at remlab dot net>
http://www.remlab.net/ndisc6/
traceroute6 $Date$ TRACEROUTE6(8)