sinister
November 5th 04, 11:27 AM
I connect from my home Windows XP home computer to a computer at work
through VPN. That computer (a Sun Solaris box) maintains a log file of
users and has a field for a hostname.
Apparently my ISP isn't handing the name server a hostname for my home
computer, and sometimes the record on the Solaris box has a completely
irrelevant hostname.
How can I set a hostname on my home PC so the name server will have
something to work with?
-------------------------------------------------------------
This is based on the following recent exchange I had on another newsgroup:
sinister wrote:
>I connect to a Solaris box via SSH over VPN from my home Windows XP Home
>box.
>
>I started finding all these weird names in the wtmpx file on the Solaris
>box. (It's a log file with a list of users, connect times, connecting
>IP/name, etc.)
>
>Called IT support and he said it was something like the following. (Pardon
>my obvious lack of knowledge of the subject.) One name server has been
>setup so that on reverse lookup the names resolve statically as
>vpn-xxx-xxx-xxx-xxx.domain.xxx. The other name server, the one the Solaris
>box queries, was setup to lookup the name based on technologies related to
>DDNS, DHCP, etc. (Here's where my lack of knowledge is showing.)
>Something
>like, when someone connects, their client can carry a name that their ISP
>passes on to the name server. These names are supposed to be deleted when
>the connection closes, but if it's not closed gracefully, they might not be
>deleted for a few days. He thought it likely that my home machine doesn't
>have such a name assigned to it, so when I connect there's nothing to
>overwrite the stale record there (if there is one) for that IP address.
>Then when the Solaris box tries reverse lookup, it's given the stale name.
>
>(1) Can I stick a name on my Windows box (something like
)
>so the stale records are overwritten?
>(2) What's the name of this technology? (I tried searching on DDNS, DHCP,
>BIND, etc, but didn't have enough knowledge to use keywords that would
>allow
>a google search to answer my question.)
>(3) Is the support guy's explanation accurate? Or is their name server not
>behaving according to specs?
>
I think I know what the guy is getting at. Many enterprise products for
DNS and DHCP (e.g. Nortel's NetID and Lucent's QIP are two that I've
worked with) have the ability to integrate the two subsystems, i.e.
whenever a DHCP lease is given out, a fully-qualified DNS name is
determined for that particular node, and the corresponding name is added
to DNS. Conversely when a DHCP lease is expired or relinquished, the
associated DNS name should be deleted. If the client doesn't send a
"hostname" (DHCP option 12) or a "client FQDN" (DHCP option 81), then
the DHCP/DNS system may simply make up a name for the client, based on
defaults, rules and/or heuristics. So if your client is not sending
either of those and you're getting different addresses from the dynamic
address range on different VPN connections, your reverse DNS resolution
may vary and you might see a bunch of "weird" names.
As far as I know there aren't any standards to govern how DNS and DHCP
are integrated, if at all.
Is this really a problem though? If you ever need to audit your own VPN
connections, then the contents of your Solaris box'es wtmpx, together
with the audit history from the DNS/DHCP system, and perhaps also from
your VPN system, you should have enough information to go on.
through VPN. That computer (a Sun Solaris box) maintains a log file of
users and has a field for a hostname.
Apparently my ISP isn't handing the name server a hostname for my home
computer, and sometimes the record on the Solaris box has a completely
irrelevant hostname.
How can I set a hostname on my home PC so the name server will have
something to work with?
-------------------------------------------------------------
This is based on the following recent exchange I had on another newsgroup:
sinister wrote:
>I connect to a Solaris box via SSH over VPN from my home Windows XP Home
>box.
>
>I started finding all these weird names in the wtmpx file on the Solaris
>box. (It's a log file with a list of users, connect times, connecting
>IP/name, etc.)
>
>Called IT support and he said it was something like the following. (Pardon
>my obvious lack of knowledge of the subject.) One name server has been
>setup so that on reverse lookup the names resolve statically as
>vpn-xxx-xxx-xxx-xxx.domain.xxx. The other name server, the one the Solaris
>box queries, was setup to lookup the name based on technologies related to
>DDNS, DHCP, etc. (Here's where my lack of knowledge is showing.)
>Something
>like, when someone connects, their client can carry a name that their ISP
>passes on to the name server. These names are supposed to be deleted when
>the connection closes, but if it's not closed gracefully, they might not be
>deleted for a few days. He thought it likely that my home machine doesn't
>have such a name assigned to it, so when I connect there's nothing to
>overwrite the stale record there (if there is one) for that IP address.
>Then when the Solaris box tries reverse lookup, it's given the stale name.
>
>(1) Can I stick a name on my Windows box (something like
)
>so the stale records are overwritten?
>(2) What's the name of this technology? (I tried searching on DDNS, DHCP,
>BIND, etc, but didn't have enough knowledge to use keywords that would
>allow
>a google search to answer my question.)
>(3) Is the support guy's explanation accurate? Or is their name server not
>behaving according to specs?
>
I think I know what the guy is getting at. Many enterprise products for
DNS and DHCP (e.g. Nortel's NetID and Lucent's QIP are two that I've
worked with) have the ability to integrate the two subsystems, i.e.
whenever a DHCP lease is given out, a fully-qualified DNS name is
determined for that particular node, and the corresponding name is added
to DNS. Conversely when a DHCP lease is expired or relinquished, the
associated DNS name should be deleted. If the client doesn't send a
"hostname" (DHCP option 12) or a "client FQDN" (DHCP option 81), then
the DHCP/DNS system may simply make up a name for the client, based on
defaults, rules and/or heuristics. So if your client is not sending
either of those and you're getting different addresses from the dynamic
address range on different VPN connections, your reverse DNS resolution
may vary and you might see a bunch of "weird" names.
As far as I know there aren't any standards to govern how DNS and DHCP
are integrated, if at all.
Is this really a problem though? If you ever need to audit your own VPN
connections, then the contents of your Solaris box'es wtmpx, together
with the audit history from the DNS/DHCP system, and perhaps also from
your VPN system, you should have enough information to go on.