Hi All,
I would like to know if Windows provides the capability to determine the
TTL value of a *received* IP packet. In Linux, one can do this using the
ancillary data(Posix standard "cmsghdr" structure). I did some search and found
that there is a "WSAMSG" structure that is supported in XP. But this provides
the capability to determine only the destination IP address and the Rx Interface
Index. Is there any other mechanism that is available in Windows that can tell
the TTL value in a received packet?

I know Windows provides the option to "set" the TTL value of an *outgoing*
packet.

Thanks in advance for any help.
-Anand

Search for DefaultTTL registry key to set with needed value as
TCP/IP & NBT Configuration Parameters for Windows NT and Windows 2000

Q120642 of KB MSDN describe.

Arkady

"Anand R" <(E-Mail Removed)> wrote in message
news:bijofj$381$(E-Mail Removed)...
> Hi All,
> I would like to know if Windows provides the capability to determine
the
> TTL value of a *received* IP packet. In Linux, one can do this using the
> ancillary data(Posix standard "cmsghdr" structure). I did some search and
found
> that there is a "WSAMSG" structure that is supported in XP. But this
provides
> the capability to determine only the destination IP address and the Rx
Interface
> Index. Is there any other mechanism that is available in Windows that can
tell
> the TTL value in a received packet?
>
> I know Windows provides the option to "set" the TTL value of an *outgoing*
> packet.
>
> Thanks in advance for any help.
> -Anand
>
>

In article <bijofj$381$(E-Mail Removed)>, "Anand R" <(E-Mail Removed)>
wrote:
> I would like to know if Windows provides the capability to determine the
>TTL value of a *received* IP packet. In Linux, one can do this using the
>ancillary data(Posix standard "cmsghdr" structure). I did some search and found
>that there is a "WSAMSG" structure that is supported in XP. But this provides
>the capability to determine only the destination IP address and the Rx
> Interface
>Index. Is there any other mechanism that is available in Windows that can tell
>the TTL value in a received packet?

It would seem to me that you're most likely to have to implement some form
of raw socket to do that. This will require you to inspect the IP header on
each packet.

Can I ask what you're planning on using this for? There are some
interesting uses for TTL, but since each OS seems to choose a different
value, sometimes changing values with service packs, and the value decreases
each hop, the TTL is somewhat of a random value by the time you get to read
it.

Alun.
~~~~

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(E-Mail Removed) (Alun Jones [MS MVP]) wrote in message news:<INs4b.21$(E-Mail Removed)>...
> In article <bijofj$381$(E-Mail Removed)>, "Anand R" <(E-Mail Removed)>
> wrote:
> > I would like to know if Windows provides the capability to determine the
> >TTL value of a *received* IP packet. In Linux, one can do this using the
> >ancillary data(Posix standard "cmsghdr" structure). I did some search and found
> >that there is a "WSAMSG" structure that is supported in XP. But this provides
> >the capability to determine only the destination IP address and the Rx
> > Interface
> >Index. Is there any other mechanism that is available in Windows that can tell
> >the TTL value in a received packet?
>
> It would seem to me that you're most likely to have to implement some form
> of raw socket to do that. This will require you to inspect the IP header on
> each packet.
>
> Can I ask what you're planning on using this for? There are some
> interesting uses for TTL, but since each OS seems to choose a different
> value, sometimes changing values with service packs, and the value decreases
> each hop, the TTL is somewhat of a random value by the time you get to read
> it.
>
> Alun.
> ~~~~
>

Check out some of the packet sniffing code that is available online,
since packet sniffers can capture every TCP/IP packet you can probably
figure out how to get the TTL field.

Look into this link it might help:

http://support.microsoft.com/default...en-us%3B224829

Zoran

"Anand R" <(E-Mail Removed)> wrote in message news:<bijofj$381$(E-Mail Removed)>...
> Hi All,
> I would like to know if Windows provides the capability to determine the
> TTL value of a *received* IP packet. In Linux, one can do this using the
> ancillary data(Posix standard "cmsghdr" structure). I did some search and found
> that there is a "WSAMSG" structure that is supported in XP. But this provides
> the capability to determine only the destination IP address and the Rx Interface
> Index. Is there any other mechanism that is available in Windows that can tell
> the TTL value in a received packet?
>
> I know Windows provides the option to "set" the TTL value of an *outgoing*
> packet.
>
> Thanks in advance for any help.
> -Anand