ping
command? Give at least 3 answers. What does
ping
actually do?
traceroute
command do? How does it do
it?
/etc/mib.txt
.
ipForwarding OBJECT-TYPE ::= { ip 1 } icmpInEchos OBJECT-TYPE ::= { icmp 8 } tcpMaxConn OBJECT-TYPE ::= { tcp 4 }What are the numeric
OBJECT IDENTIFIERS
of the objects
ipForwarding
, icmpInEchoes
and
tcpMaxConn
.
OBJECT IDENTIFIERS
are encoded for transmission. In
general, the integers which
specify the OBJECT IDENTIFIER
are simply encoded in BER as
a SEQUENCE
of single byte values. However, the first two
integers (let's call them a and b) are encoded
in a compact form, taking only a single byte, of the form 40a +
b. So, for the Internet, the first two integers are 1.3,
therefore they are encoded as the single byte value 43. Can you imagine
a reason why this is done? What does it say about the values of these
first two integers?
ping
[2] command
to check reachability of various hosts at
Bendigo and elsewhere. Now investigate the command line options of
ping
. If you're not on campus, there are versions of
ping
for virtually all combinations of hardware and
operating system -- see what you
can find on the various 'net archives.
traceroute
command is available on ironbark/redgum
and the Indys, as well as for PCs and Macs. Use
traceroute
(judiciously - see its documentation). You might
also be interested to have a look at
ntping
on the SGI systems (Indys, ironbark -- try
ntping -trace 30 hostname
).
netstat
. Try a few of its command line options.
The most interesting option is netstat -C
. Can you make
sense of the display, and the various options?
/usr/etc
, which
may not be in your path.