How to obtain remote ip address without using DNS?

[Fabricio_5]

How do I obtain the remote ip address of a computer connected via telnet using the 23 port without using hostname and any dns service. Imaging that DNS and hostname does not exist, how can I do that?

[RAC_1]

who -u (Check the last column)
arp -a

Hope this helps.

Anil

[Muthukumar_5]

You can get the specific login informations with who command as,

getip `who -mu | awk '{ print $8 }'`

You can use netstat -na | grep 'localserverip.23'
will give all ip-address login in the system.

You can also use last command to get login informations there with ip-address.

HTH.

[Fabricio_5]

The arp -a command gives me lots of hostnames and ip addresses and the who -u command gives me the hostname.

I want to print only the remote ip address in the screen.

[Sanjay_6]

hi,

Try "who -R" which gives the ip address. It gives a list.

Hope this helps.

regds

[rick jones]

The manpage for arp describes the '-n' option that suppresses host and port number lookups.

Just as the -n option in netstat does.

[Geoff Wild]

I'd say that to answer your question - this is impossible.

Basically - everything mentioned uses the DNS resovler routines to provide the result.

who uses gethostname and gethostbyaddr...

Right from the who man page:

-R Displays the user's host name. If the user is
logged in on a tty, who displays the string
returned from gethostname() (see gethostname(2)).
If the user is not logged in on a tty and the host
name stored in the /etc/utmp or named file has not
been truncated when stored (meaning that the
entire host name was stored with no loss of
information), it is displayed as it was stored.
Otherwise, the gethostbyaddr() function is called
with the internet address of the host (see
gethostent(3N)). The host name returned by
gethostbyaddr() is displayed unless it returns an
error, in which case the truncated host name is
displayed.

Rgds...Geoff