FTP Client problems from 2008 r2 box

[fox1977]

Hi there,

 

Just wondering if anyone can offer any advice i am having with a strange FTP connection problem.

 

I have a 2008 r2 server running at one site. This is a backup server and I have a scheduled FTP job setup to transfer backups to another site through a router, over VPN, to an FTP server on another of our sites. All was working on for several weeks and now we are experiencing connection problems with any FTP client from the server (to any FTP server).

 

Here's what is happening. I am able to connect filezilla to the FTP server and I retreive the directory listing without any problems. I then start to upload any file and after anywhere between 2-4 minutes the connection/speed seems to drop. The speed then starts to crawl and eventually reconnects. The client then reconnects several times before the FTP server states too many connections.

 

I initially thought this was a firewall issues so carried out a couple of checks. I have checked the firewall rules and all are setup as they were with rules to allow for FTP access through the firewall. So far I have ruled out any isses with the FTP server by connecting to the server from the same site as the FTP server - works ok. I was able to connect to the FTP server ok from a desktop between the two sites. This is what I thought was a little odd as from other machines (win7) the FTP client running across the same site works ok going through the firewall.

 

I then tried connecting to a second FTP server from one site to another. This didn't work either and indicates an issue with the server. Connecting out to any FTP server (using any FTP client) doesn't seem to want to work. I've disabled the windows firewall on the server but this hasn't made a bit of difference.

 

As a long shot ive just been and changed the network cable and switch port.

 

Anyone any ideas on how to trouble shoot this further as I'm running out of ideas.

 

Thanks in advance

[kmount]

Is it a site to site VPN or is the server itself initiating the connection?

 

From the problematic source server can you talk to any other servers on the far end (not using FTP) to confirm the VPN link / route is valid?

 

If you try from a different source server at Site A can it see the machines at site B that the problematic server cannot?

 

Are the routing tables the same?

[sukh]

1. Capture the traffic on the site firewall and server and see what's happening.

2. Try anonther server from A to B and see if this works (FTP)

 

Sukh

[tumbleweed]

Can you try ftp Passive mode - sometimes called 'firewall friendly' ?

Have seen similar issues in the past, due to the way ftp works with both a command and a data port.

Sometimes the network connection can be killed as there's no traffic on the command port whilst a data transfer is going.

The hash command can also be useful, by creating extra data on the command port.

[fox1977]

Hi,

 

Kmount, it is a site to site vpn. The vpn is working fine as we have a number of connections/services running over it with no problems. The connection is fine and staying connected. When i ftp from my desktop (in same subnet to the same devices) it works fine and is stable.

 

Not sure about the routing tables, but the majority of services across the VPN are working ok so I guess so.

 

Sukh, I will have a look at capturing the traffic. Other servers/desktops work fine. Ive had the same job running from my desktop overnight and it has been stable

 

Stumped! Thanks for the tips anyway! Need a sanity check :-)

[fox1977]

Hi All,

 

Just an update as we are making a bit of progress. We managed to get wireshark up and running and captured the information. Whilst this worked we struggled to interpret anything useful from the captured packets.

 

We tried looking at the patch levels of two win 2008 servers as they were both experiencing the same issues. We patched one of the servers but this still made no difference.

 

We managed successfully to get the FTP jobs to run without a problem by setting the NIC on the server (within Windows 2008) to 100mb. This works seamlessly now. I have since tried to manually set the switch ports to 1gb and the NIC thinking that it may be an autosensing issue but this failed to work either.

 

At least I am getting somewhere at long last and I can try and get my FTP off site replication back up and running again. Anyone any ideas? Could it be related to the new networking stack in win 2008 (Although it works fine on a windows 7 desktop going over a 100mb link).

 

When running the FTP job it always fails between 2:30 and 3:00 minutes after starting at starts to spawn new connections

Edited May 17, 2011 by fox1977

[fox1977]

I have since installed SP2 on the box and it hasn't made any difference. If anything it has made it worse! I have also tried it with a different physical network card in the server but this seems to be the same.