topic Re: Hardware-address with IP-address in Operating System - OpenVMS

Hardware-address with IP-address

Kirsten Knüttel — Thu, 29 Sep 2005 06:03:01 GMT

Hi,

I'm using TCPIP V. 5.3 Eco2 and have a question. For a program I need the following thing. I have the IP-address of a client and I'm now searching for the hardware / mac-address. Normally we use TCPIP show arp but at the moment (the collegues are installing a new network) I don't receive the hardware address.
Under windows I can use for this
nbtstat -A ip-address
Does I have something like this under VMS, too or does somebody know another way to find the hardware address when I only have the IP-address?

Regards,

Kirsten

Re: Hardware-address with IP-address

Karl Rohwedder — Thu, 29 Sep 2005 06:15:10 GMT

I assume that in that case a

$ TCPIP netstat "-H"

doesn't work either (don't know for sure if it is supported under V5.3)?

regards Kalle

Re: Hardware-address with IP-address

Volker Halle — Thu, 29 Sep 2005 06:26:30 GMT

Kirsten,

I don't think there is any way to obtain the remote node's hardware address, if that node is not currently connected to the network and it's entries in the ARP cache have timed out.

Volker.

Re: Hardware-address with IP-address

Kirsten Knüttel — Thu, 29 Sep 2005 06:36:37 GMT

Hi Volker,

the problem is, that the client is connected to the network, I can ping the client, no problem. Under windows with nbtstat I receive the hardware address. But I don't know a way under VMS.

Regards,

Kirsten

Re: Hardware-address with IP-address

Volker Halle — Thu, 29 Sep 2005 06:41:21 GMT

Kirsten,

then the client is most probably on another LAN and you are communicating to the client via a router. ARP only works on the local LAN. You would have to ask the router about the client's hardware address.

nbtstat may only show you the client's hardware address, IF any NetBIOS over TCP/IP connection is currently active.

Volker.

Re: Hardware-address with IP-address

Willem Grooters — Thu, 29 Sep 2005 06:53:02 GMT

A wild shot or hint: could SNMP deliver the requested information (it must then be enabled, I know)

Re: Hardware-address with IP-address

Uwe Zessin — Thu, 29 Sep 2005 06:58:04 GMT

Another reason why you might not be able to find it out from a remote system is if there is a router between both nodes.

Re: Hardware-address with IP-address

Joseph Huber_1 — Thu, 29 Sep 2005 07:01:59 GMT

TCPIP netstat "-H" (or "netstat -H" after executing TCPIP$DEFINE_COMMANDS.COM) does work under TCPIP 5.3 as well.

But as said, it needs the address in the ARP tables.

Maybe a difference to Windoze is: the TCPIP services ARP cache interval seems to be shorter.