Machine will not see network at other site

you have two firewalls between you?

for ping to work ICMP needs to be open on both firewalls in both directions

to actually see domain resources theres a raft of other ports that need to be open

Logging into the domain through a Firewall

Note this is to log in - NOT for Exchange, SQL or a Domain Controller, I’ve not tried those so I can't comment.

The following ports have to be open from the outside (or DMZ) to the domain controllers.
NB: I know having these open from outside/DMZ has security implications but sometimes it needs to be done.

Ports open from DMZ\Outside


UDP      domain            53
TCP      domain            53
UDP      Kerberos            88
TCP      Kerberos            88
UDP      Time                  123
TCP      Kerberos Auth      135
UDP      netbios-ns            137
TCP      netbios-ssn            139
TCP      ldap                  389
UDP      ldap                  389
TCP      microsoft-ds            445
TCP      ldap to GC            3268

However the process still fails (or runs like a two legged dog and appears to work) this is because
of the RPC system that runs on the domain controllers, when you log in the client fires up a
communication over port 135 the Domain controller, which then fires back a port number it wants to communicate
with the client over (this can be any number over 1024) your firewall lets this through outbound.

When it hits your client, it tries to open comms on that port, which is inevitably blocked on the firewall

When this happens you will see errors like

Error 1053
There are no more endpoints available from the endpoint mapper.

if you run netdiag on the machine you will see errors like
[WARNING] Cannot call DsBind to servername.domain_name.com (<ip address>). [EPT_S_NOT_REGISTERED]

There are two ways to solve the problem

1. Open every port above 1024 on your firewall, however this is about as sensible as eating yellow snow.

2. Change the way your domain controller handles RPC requests,

NOTE this must be done on EVERY domain controller

Click Start > Run > regedit {enter}

Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\

Create a new DWORD value called "TCP/IP Port"  (remove the quotes and include the space)
double click it and change the "base" to decimal type in a port number (between 1024 and 64000) for the sake of argument use 1024

Exit the Registry Editor and you MUST reboot the server.

Now go back to the Firewall and open the following port

 
TCP      static RPC      1024


Now the process will work.

Hi there,

Ping works fine from every other machine. We have about 50 machines here that have no problem at all in seeing the network at the other site.

So I assumed it must be a problem with the laptop...

Do I need to add a route on the laptop? We had to do this to some other machines a while back but that was to see a different server at the other site... not sure on the theory behind it all...

If so, what is the syntax for the route? Thanks.

gjirvine3000,
OK can the laptop ping other resources on the same LAN?


Pete

Hi Pete,

Yes the laptop can ping our domain server here and all other machines on our network here - just can't see across to the other site.

gjirvine3000,
also run

ipconfig /all

on the laptop and make sure it has the SAME default gateway as all the other PC's on the same site (that work)

if still no joy run (connectivity wise) run this http://www.petenetlive.com/Downloads/software/WinsockFix.exe
Pete

PeteLong,
if its the only machine that cant access the other side

then either

the subnet mask is wrong on the laptop
the default gateway is wrong on the client
The clients IP address id blocked on the firewall

go toy a working Client and get its IP address (ipconfig/ all) turn that client off!
put the IP address you got above on the laptop - if it suddenly starts working then you have a routing/firewall problem
if it still doesnt work the problem is on the laptop

Pete

How's pinging the ip address of the other side's machines? What is the network mask and default gateway of the laptop? Have you installed w2k sp4 on laptop?

Hello chaps,

Thanks for your responses. Further investigation has shown that:

- It makes no difference if I add a static IP to the laptop that I know is working
- I cannot ping any machine at the other site
- the network mask of the laptop is 255.255.255.0 and the default gateway is 192.9.200.254 (same as a working machine)
- w2k sp4 is installed on the laptop
- the IP we are trying to reach is 192.10.200.94 (or any 192.10.200.x address)
- I think that the route is at fault but don't know what the syntax should be for the route?

Thanks

Hi there,

I have been using the wrong default gateway in the route I was setting up on the machine.

I did actually add a route with the right default gateway to try it out and it didn't work, I hadn't realised I needed to also delete the route with the wrong default gateway!

Thanks for all your help. Sorted and working now.

ThanQ