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Unc + Other Service Fail. Ping Okay.


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I have sites all over the UK which i manage the network for, and well i have a really strange problem, which i hope someone has seen before and may be able to help.

Okay....

DR Datacenter:

Mutiple Vlans all /24 netmask

Cisco network kit.

OSPF running with three layer 3 links out. -> 2x MPLS 1 x leased line to Production Datacenter

Local DNS server -> checked working properly.

All routing is working fine.

Branch Office:

Vlan /24 netmask

Cisco network kit.

Connected to MPLS network.

Local DNS server -> checked working properly.

All routing is working fine.

MPLS Confirmed okay.

Server in data center is having problems connecting to servers in brance office.

Ping is okay.

Resolves DNS.

routing the right way.

if i ask for a service over the IP network it fails.

For example i try a UNC path to server from DR datacenter to the branch office and i get:

'no network provider accepted the given network path'

This is not isolated to 2 servers this is any servers in those two sites.

Other sites connect to each server fine.

Any experience with this ?

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Taking a stab at this, and this is going to sound really stupid, but has anyone checked to see if the servers running the services failed on the servers themselves? Can you remote desktop into the workstations over RDP/Terminal Services or such, check whats running on them? Ping simply means the machine is responding, doesn't mean the services required for the shares on the Domain Controller haven't stopped or failed.

Something may have failed on one of the servers or crashed and can't be reached and require a reboot even or restart of the "server" service, etc, you are trying to reach shares through, and may have failed or stopped, and just need restarting. Check services.msc on the main domain controller at the remote site, make sure everything is running as should be.

Also, not sure how critical it would impact you, but there was an attack on all the root name servers yesterday for DNS, but I don't know how that effects people's WAN's in general, if a ping returns replies, that simply means the host is there, but doesn't guarantee the DNS services themselves haven't went down or failed and stopped which enable the shares to be seen or other services on the remote sites main server haven't fallen over and need a restart.

You could also try nmapping the server at the remote location, but if you have firewalls or IDS that block that sort of stuff, won't see them, but if VPN'ed into the remote site, should be able to do it from the local lan through the VPN to check if the services are up, but I would RDP into the main server and just check services.msc and run down the list of whats running before even bothering with nmapping to see what it can see. If all services are running that are needed for file shares, then do the nmap stuff and trace routes, and see where they stop and if they reach their last hop for those services. Just add the traceroute command with your nmap ping for services, like a firewalk scan.

Also, make sure no one changed firewall rules at the remote site, or is filtering ports for the services.

Edited by digip
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I controll all networking and securtity for the UK and the servers are accessable via the same means.

I suspected that this was to do with NLM but i cannot see how. As the logons are from domain accounts RDP working file all ports & services are running.

As i said, our main datacenter can connect with no issues, and the DR datacenter cannot. I this this liyes well benith the basics.

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What about router and switch configurations, ACL's, ingress and egress filtering and such on the network? I know sometimes you can screw up Cisco topologies when making changes that weren't meant to propagate to certain devices and routing tables get all whacky, but if you can RDP in, then its not like services aren't working, something else on your network is foul somewhere.

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