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multihomed and isololating one nic

Question: multihomed and isololating one nic

It seems that when a machine has dual nics it likes to share that fact with other machines. Here's my scenario:

I have a server, ServerA, with two nics. One with a 150.102.x.x address to the corporate network and one with a 10.x.x.x address for a private network.

When I map a drive to another server, ServerB, over the 150.102.x.x nic it also seems to share the fact that it has a 10.x.x.x interface too. Where I see this is on ServerB. If I do a netstat command on ServerB, I will see both ServerA addresses at the time of mapping the drive and periodically at other times.

Is there some way to setup ServerA so that the two nics are totally isolated from each other. Basically that the 10.x only ever needs to communicate with 10.x machines and the 150.102.x would be the interface to use for any other type communication


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Answer: multihomed and isololating one nic

Does it seem like the info below under DETAILS might apply. If RandomAdapter = 0 (disabled) and SingleResponse = 1, would it only use the adapter the request came in on?

Load balancing over several Network Adapters Post Comment
It is possible to have the OS to balance the network load for the computer when having several Network Adapters.

This is controlled by these DWORD values :

[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \NetBT \Parameters]
RandomAdapter = 1 (Disabled = 0, Enabled = 1, Default = 0)
SingleResponse = 1 (Send All = 0, Send One = 1, Default = 0)

The RandomAdapter specifies whether it should respond back with a random IP-Address (One for each adapter), or if it should respond back with the IP Address for the adapter the request was received from.

The SingleResponse says that it should only send one IP address when WINS does a name query request.

More Info MS KB Q131736
More Info MS KB Q175767

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I have a friend that is need of a multihomed router do that she can do stuff for her business, she does alot of VOIP and remote desktop stuff. and when she does remote desktop and sending a file her VOIP goes crazy and either drops the connection or is very staticy.

I have found this product, looks promising. It is made by Edimax and can use up to 4 wan connections.

The problem is i've only found the edimax br-6541 on only a couple of websites, which makes me kind of weary about the product. however i had read good reviews.

Is there any otehr way to multihome multiple cable connections or dsl/cable connections.

Thanks for any replys

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hi guys,

my friend called me to his office as his whole network was down.
i couldnt log into the edimax dsl modem as i didnt have the password and the default password didnt work
so i had to reset it...but nothing was working

i then configured a netopia modem from eircom to use BT and its working straight into a laptop
i gave the router an ip address of as this is what dhcp is allocating to clients

from the netopia (eircom) dsl modem there is a cable to the server (win sbs2003) in the top port which the connection is called internet
it is configured
dg = which i cant ping
dns is set to

the server local connection was set to dhcp...which made no sense to me.
none of the clients were getting ip addresses just the yellow exclamation mark limited connection with a 169 network address.
i then configured the internal address of the server to
and dns for

the clients then got ip addresses through dhcp but i still had no internet...i then plugged the cable from edimax going into the server straight into the switch and i have internet now...

if you have one configured network card on a server and the brodband going into do you get the broadband to go through the internal nic to the rest of your network??? is there possibly a firewall? i cant see any firewall... do i need to setup routing on the server to move it to the other nic. this seems very confusing... Read more

Answer:internet through multihomed server

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I have a multihomed nt4 server set up the following way in a test network:
one nic plugged into a 10base hub, one nic plugged into a 100base hub. The
10base hub is built in to the router, and the 100base hub will have
workstations, servers, printers, etc. plugged into it. From the server I
can ping outside the router, but nothing inside. I also have a workstation
plugged into the 100 hub and can ping only the nic plugged into the 100
hub, nothing else. The server and workstation both have the same gateway,
subnet mask, etc. Ip forwarding is enabled on the server. Furthermore, no
new hardware (switches) may be introduced. Anyone have a clue, because I
sure dont.

Answer:Multihomed Server Question


I have a feeling that the Subnet mask for the router-hub is incorrect. It sees no IP address as being local, and all IPs as external... so it can see IPs outside the router, but not on its side of the router.

Remember, the Subnet masks do not HAVE to be the same from one router to the next, it all depends on what your IP address scheme is.

It would help to know the actual Ips of all the relevant hardware in this scenario, and what kind of subnetting you have in place.


Reuel Miller
Windows NT Moderator (yes, that does make me biased )

[email protected]

Every morning is the dawn of a new error...

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I have a Cisco router connecting my network to the internet. Its address is I have a NTv4 web server at and it browses fine. I want to have a NTv4 LAN server with 2 NICs, the 1st NIC at exposed to the router and the 2nd NIC at to give out DHCP addresses to the LAN clients.

When I first set this up, all servers can easily browse the internet. What isn't happening is for the LAN clients to browse the internet. At first, DHCP wasn't giving them a gateway value. I now know how to give the DHCP clients a default gateway value. Still, no good. These are the values in Network Properties:

WAN exposed NIC:
Addr -
Mask -
Gate -

Addr -
Mask -
Gate - blank (also tried )

WINS - (Primary and Sencondary)
DNS - from ISP
IP Forwarding Enabled
RIP for IP installed

DHCP - - 170
DHCP Scope Router value -
no proxy server installed
have had no luck with static routing either.

Goal: Would like LAN client browsing to pass through NT 4 Router to the Cisco Router. Call me paranoid.

Answer:NT 4.0 Multihomed - Internal Routing?

Do I need to have the DHCP Relay Agent installed to cross the subnets? I wonder if that might be what's missing.

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Hi. Is it possible to exclude a network interface from NetBIOS? When i run nbtstat -A * i see a list of 2 interfaces (as i have 2 NICs). I've searched google, msdn the forum and cannot find a way to exclude an interface from being in this list (and therefore not being included in the response to name queries). I've tried disabling NetBIOS over TCP in the advanced TCP/IP tab of the interface and also unchecking "file sharing" - the interface is always in the list. Is this possible on windows xp?


Answer:NetBIOS on multihomed PC - excluding interfaces?

Please explain what you are trying to achieve by doing this as there could be another way.

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Hey there,

The only thing I love more than working on sunday is the fact that my exchange server sends all of it's mail out from the wrong NIC.

Here's the deal:
Exchange 2000 running on Windows 2000
internal nic: 1gbps, 10.0.223.x
external-ish nic: 100mbps, 10.0.222.x (static nat'd to a public ip)

The thing is...most of my mail is leaving the exchange server through the 10.0.223 interface instead of the 10.0.222 int.

Is is choosing the 223 nic, because of it's capacity or something?
Well either way, is there a way of directing the email through the correct nic?

fyi~This is causing some emails to not be delivered to places that check the header/sent-from ip to the registered ip for the email server...and if they don't match, the mail gets dropped.

Thank ye's...

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Hopefully I can finally get this figured out since I've been pulling my hair out searching for a solution. Here's the situation :

In the office we have a fiber line with 5 IP's going into an external nic on a multihomed windows 2003 RRAS server using NAT. 2nd internal nat goes into internal network with private IPs :

Ext Nic IP with assigned netmask and gateway 209.x.x.98
Int Nic subnet no gateway.

The NAT is working fine for sharing the internet within the office but I also have a block of IPs from 100-105 that i want to use on internal servers (with direct access to the outside world)

IPRouting is enabled in the registry

Basically I have an internal IIS6 server on and I want to add an external IP (not just port forward) of 209.x.x.105. I can only ping the 105 IP when I add it directly to the RRAS server (obviously not what I want)

If someone could please shed any light on the subject or point me in the right direction I'd appreciate it as I'd have my sanity back.

Answer:Multihomed RRAS server IP forwarding help.

Wow, I think what you need is a real firewall. I've never seen RRAS in a production environment doing multiple NAT translations for separate internal clients. Is this just a vanilla 2003 server runnint RRAS or is this at least ISA server?

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OK so here's my situation:
So, I got blowed up

My office building is closed and off limits, and probably will be until next week sometime (building management says there is asbestos contamination)

What that means for me is that the users that work out of this office are all working from home, either through OWA or remote desktop.
We have a second site in Stamford CT, which is the initial e-mail entry point (mail flows from internet to CT then to NY via exchange transports)

My problem is, due to the situation in that area, the building MAY have to be without power.
If that happens, then NY users will be without mail.

Is there ANY way, *without* moving their mailboxes, to have them setup in such a way that mail will be delivered to a mailbox store in CT, and have them be able to login to that mailbox?
Mailbox store replication? Some other means?

We use GFI Mailarchiver in the CT site, which will allow our users to read their mail (I hope, not sure how exchange journaling works). Is there something I can use in conjunction with that to allow them to send mail?

Can I finagle say a second mailbox (minus a user account in AD) and set alternate recipients, and then have my users login to those alternate mailboxes?
(say via OWA, IMAP, or even outlook?)

I am by no means an exchange expert, and everything I am reading is telling me "NO".
I see things for geographically seperate clustered exchange backup sites, but 1) It looks VERY cost proh... Read more

Answer:multihomed mailboxes in Exchange 2003?

I would say you observations are all correct. The systems that allow you to do this are fairly expensive and need to be in place before something like this happens. I think you are SOL...

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Relevance 49.61% I'm a security analyst, not a network engineer. As such, all my understanding of how networks are set up is basically conceptual. That said, I have a few extra computers laying around, and decided to run a NIDS on my home network. The machine I plan to use as a sensor has two ethernet NICs and a wifi card. Basically, I want to plug the modem into one ethernet port, and the router into the other, and have the machine inspect the packets as they pass through...this should give me visibility on every packet that enters or leaves my network. Problem is, I have no idea how to configure this. I wish it was as easy as 'plug and play,' but clearly that isn't going to work. How do I set up the machine to take traffic coming from the modem on one ethernet card, and pass it along to the router on the other?

Let's router, unfortunately, is not configurable for SPAN, so that won't work. I have a DIR-868L Wireless AC router, and the machine I want to use as a sensor is running Windows 8.1

What other information might anyone need in order to help me out with this?

Answer:Using a multihomed PC to sniff traffic inline

Let's sync up on the concept, you want

ISP=>modem<--->MonitoringPC<-->siteRouter <- - -> all lan attached users.

You realize that the MonitoringPC will need to disable its firewall and thus be exposed to all sorts of exposures.

You have at least two instrumentation points (a) the modem-side port vs (b) the router side port AND
you need the routing table tweaked.

If you place software between (a) & (b) ports, then there's a proxy to be configured.

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My topology is as in the attachment. I cannot understand what I am doing wrong.

I am wanting the network to be setup to where my 2 machines (that are wired to the router, and multihomed, the second port with a 1gb NIC using crossover to each machine for file transfers. Any time I have it set up, it either refuses to connect to the internet (using various commands I found that it is because I had a default gateway set to the 1gb NIC with the crossover, and it was choosing to use it for internet access) or the two machines refuse to even ping one another (without a gateway).

I've tried under different subnets (eg, with subnet and I've tried with subnet and neither work, bot have the same problems. I have Homegroups disabled, file and print sharing set with accounts.

Windows 7 Professional on each machine, Linksys BEFVP41 router.

What am I missing??

Thanks for reading.

Answer:Help with simple setup - two multihomed PC's, one router, one patch cable

I think your problem is using the crossover. AFAIK, you are supposed to use the regular CAT5E/CAT6 cable in order to connect to the internet, and as well hooking the rest network to the internet.

I assumed that your modem has more than one ports for hooking up your network, so use that, it's there for the reasons, or you could buy the used/new router to hook up the rest of your computers on a network.
This simple topology on network should be at:

COMPUTER 1----\..............................................................................................
...........................|======= ROUTER / MODEM =============== INTERNET
COMPUTER 2----/..........(DHCP/ STATIC IP from ISP).................( ISP provided IP)

The " === " is translated as cable connection between devices and computers.
Good way of using your network efficiently is to research info between the network router and ISP. ( Assigned IP at; Router IP ( check manual); and assigned router IP for your computers. )
Hope I helped.
Edited: I just realized that you set Computer 1 as assigned IP while the computer 2 has DHCP enabled. I think you need to set both computer as your router address, and then set the IP to be assigned from Router to your computer's DHCP.

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