topic Re: Getting Network Mask Address in Operating System - OpenVMS

Getting Network Mask Address

Vineet Deshpande — Thu, 26 Nov 2009 08:35:43 GMT

Hi,

I want to know if there is any DCL command which will give me the Network Mask address. I am getting it from "tcpip show interface" but this command won't work if MultiNet is present. Is there any generic command which will give me the Mask address?

Please help.

Thanks,

Vineet

Re: Getting Network Mask Address

Joseph Huber_1 — Thu, 26 Nov 2009 09:58:03 GMT

Since TCP/IP is not generic in VMS, there is no generic interface. And there is no programming API I know of.

What comes nearest would be using "ifconfig -a"
and parse the output.
But the output format is still TCPIP stack dependent, so You have to write your own parsing (DCL-)program to extract the info wanted.

Re: Getting Network Mask Address

Joseph Huber_1 — Thu, 26 Nov 2009 10:02:32 GMT

And be aware:there is no such thing than "the" network mask:
each interface has its own, and will be different: if one IF is connected to the outside world, the another to the local LAN (e.g. a 10.* or 192.168.*.* network), then they certainly have different netmask and broadcast addresses.

Re: Getting Network Mask Address

Robert Gezelter — Thu, 26 Nov 2009 12:27:36 GMT

Vineet,

There is no universal DCL command to get the network address.

In Multinet, the information is generally accessed by looking at the configuration information by using the MULTINET CONFIGURE command.

- Bob Gezelter, http://www.rlgsc.com

Re: Getting Network Mask Address

Ian Miller. — Thu, 26 Nov 2009 12:38:23 GMT

For TCPWARE and MULTINET this data may be available in a logical name

Re: Getting Network Mask Address

labadie_1 — Thu, 26 Nov 2009 13:08:24 GMT

The following works with Alpha VMS 7.3-2 (and not Itanium :-)

$ @sys$startup:tcpip$define_commands
$ awk :== $ sys$common:[syshlp.examples.tcpip.snmp]gawk.exe
$ pipe ifconfig -a | awk/command="/broadcast/ {print $1}" sys$pipe

This will print the broadcast mask, not the network mask.

Re: Getting Network Mask Address

Joseph Huber_1 — Thu, 26 Nov 2009 13:37:15 GMT

On my TCPIP system the following

pipe ifconfig -a | awk/command="/netmask/ {print $4}" sys$pipe

prints all netmasks on all interfaces.

Re: Getting Network Mask Address

labadie_1 — Thu, 26 Nov 2009 14:02:02 GMT

Taking Joseph'idea, the following works if you have only a network card (but you get the idea)

$ pipe ifconfig -a | awk/command="/netmask/ {print $4}" sys$pipe | (read sys$pipe in ; def/job in &in)
$ x1=%X'f$extract(0,2,f$trn("in"))
$ x2=%X'f$extract(2,2,f$trn("in"))
$ x3=%X'f$extract(4,2,f$trn("in"))
$ x4=%X'f$extract(6,2,f$trn("in"))
$ res:='X1'"."'X2'"."'X3'"."'X4'
$ wr sys$output "the network mask is ''res'"

Re: Getting Network Mask Address

Hoff — Thu, 26 Nov 2009 14:08:51 GMT

This usually ends up involving prompting the user directly, or querying the lower-level IP stack APIs (the C socket library) within the application.

As for the request, please lodge a formal request with HP.

It is long past time that there be a DCL lexical function for this, and/or a DCL command interface that works with all of the IP stacks.

And FWIW as you proceed with this, remember that IPv6 is in play here, too. (Yes, there are OpenVMS systems running on IPv6 networks. More will be coming on-line, too.)