clockdiff(8) [linux man page]

CLOCKDIFF(8)						 System Manager's Manual: iputils					      CLOCKDIFF(8)

NAME

       clockdiff - measure clock difference between hosts

SYNOPSIS

       clockdiff [-o] [-o1] destination

DESCRIPTION

       clockdiff  Measures  clock difference between us and destination with 1 msec resolution using ICMP TIMESTAMP [2] packets or, optionally, IP
       TIMESTAMP option [3] option added to ICMP ECHO.	[1]

OPTIONS

       -o     Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP messages. It is useful with some destinations, which do not  support  ICMP
	      TIMESTAMP (f.e. Solaris <2.4).

       -o1    Slightly	different  form  of  -o,  namely it uses three-term IP TIMESTAMP with prespecified hop addresses instead of four term one.
	      What flavor works better depends on target host. Particularly, -o is better for Linux.

WARNINGS

       o Some nodes (Cisco) use non-standard timestamps, which is allowed by RFC, but makes timestamps mostly useless.

       o Some nodes generate messed timestamps (Solaris>2.4), when run xntpd. Seems, its IP stack uses a corrupted clock source, which is synchro-
	 nized	to  time-of-day  clock periodically and jumps randomly making timestamps mostly useless. Good news is that you can use NTP in this
	 case, which is even better.

       o clockdiff shows difference in time modulo 24 days.

SEE ALSO

       ping(8), arping(8), tracepath(8).

REFERENCES

       [1] ICMP ECHO, RFC0792, page 14.

       [2] ICMP TIMESTAMP, RFC0792, page 16.

       [3] IP TIMESTAMP option, RFC0791, 3.1, page 16.

AUTHOR

       clockdiff was compiled by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>. It was based on code borrowed from BSD timed daemon.	It  is	now  main-
       tained by YOSHIFUJI Hideaki <yoshfuji@skbuff.net>.

SECURITY

       clockdiff requires CAP_NET_RAWIO capability to be executed. It is safe to be used as set-uid root.

AVAILABILITY

       clockdiff  is  part  of iputils package and the latest versions are  available in source form at http://www.skbuff.net/iputils/iputils-cur-
       rent.tar.bz2.

iputils-101006							   12 April 2011						      CLOCKDIFF(8)

ARPING(8)                                                System Manager's Manual: iputils                                                ARPING(8)

NAME

       arping - send ARP REQUEST to a neighbour host

SYNOPSIS

       arping [-AbDfhqUV] [-c count] [-w deadline] [-s source] -I interface destination

DESCRIPTION

       Ping destination on device interface by ARP packets, using source address source.

OPTIONS

       -A     The same as -U, but ARP REPLY packets used instead of ARP REQUEST.

       -b     Send only MAC level broadcasts. Normally arping starts from sending broadcast, and switch to unicast after reply received.

       -c count
              Stop  after  sending  count  ARP  REQUEST packets. With deadline option, arping waits for count ARP REPLY packets, until the timeout
              expires.

       -D     Duplicate address detection mode (DAD). See RFC2131, 4.4.1.  Returns 0, if DAD succeeded i.e. no replies are received

       -f     Finish after the first reply confirming that target is alive.

       -I interface
              Name of network device where to send ARP REQUEST packets. This option is required.

       -h     Print help page and exit.

       -q     Quiet output. Nothing is displayed.

       -s source
              IP source address to use in ARP packets.  If this option is absent, source address is:

              o In DAD mode (with option -D) set to 0.0.0.0.

              o In Unsolicited ARP mode (with options -U or -A) set to destination.

              o Otherwise, it is calculated from routing tables.

       -U     Unsolicited ARP mode to update neighbours' ARP caches.  No replies are expected.

       -V     Print version of the program and exit.

       -w deadline
              Specify a timeout, in seconds, before arping exits regardless of how many packets have been sent or received. In  this  case  arping
              does not stop after count packet are sent, it waits either for deadline expire or until count probes are answered.

SEE ALSO

       ping(8), clockdiff(8), tracepath(8).

AUTHOR

       arping was written by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>.  It is now maintained by YOSHIFUJI Hideaki <yoshfuji@skbuff.net>.

SECURITY

       arping requires CAP_NET_RAWIO capability to be executed. It is not recommended to be used as set-uid root, because it allows user to modify
       ARP caches of neighbour hosts.

AVAILABILITY

       arping is part of iputils package and the latest versions are   available  in  source  form  at  http://www.skbuff.net/iputils/iputils-cur-
       rent.tar.bz2.

iputils-101006                                                     12 April 2011                                                         ARPING(8)