Troubleshooting IIS 7 network performance issues and TCP Chimney Offload, Receive Side Scaling, and Network Direct Memory Access

There is a lot of posts on related to network performance.  Actually, there was two today!.  The problems can be different, but the common thread seems to be network performance.  Windows Server 2008 (and R2) enabled a new network feature by default which has been referred to as “Scalable Networking Pak”.  Some people refer to the feature as TCP Chimney Offload.  Either way, in my experience this feature causes more issues than it solves.  If you are having a network related issue or performance, this is a easy setting to check and verify if disabling portions or all of them can resolve the issue.  

KB article on TCP Chimney Offload

KB Article how to show your settings and disable

I strongly encourage test these changes in a non-production environment before making changes to your production systems!


Steve Schofield
Microsoft MVP – IIS

New Article on using IISLogs with UAC (user account control) enabled

UAC  was introduced in Vista and in my personal opinion was not done very well.  With the introduction of Windows 7, Windows Server 2008 R2, Microsoft did a better job with UAC.   The jury is still out if it’s universal setting that stays enabled.  🙂  I wrote an article discussing how to configure IISLogs 2.0 with UAC enabled.


Steve Schofield
Microsoft MVP – IIS

WinSCP, command line SFTP and automation

I had a co-worker ask me about using WinSCP for automating SFTP puts to a remote host.    I personally have never setup a SFTP server nor use SFTP client (or it’s been a while :)).   There is a thread on that has great information.   I included the link to the post.  The one thing I used for my test was FreeFTPD, which was real straight forward.  It seems to support NT Authentication.  I tried a couple of times, seems to be lacking a easy feature to extend to an entire Active Directory environment.  For my testing, it was very good.    I setup on Windows Server 2008 R2 with no issues.  I’ve setup FTP over SSL too and it’s a different solution.  Depends on your requirements. 

//Syntax I used on my client to automate. 
//”C:\Program Files\WinSCP\” /script:”C:\Program Files\WinSCP\WinSCP.txt”                                                                          

option batch on
option confirm off
open sftp://SCS:MyPass@ -hostkey=”ssh-rsa 1024 42:9e:c7:f4:7f:8b:50:10:6a:06:04:b1:d4:f2:04:6d”
cd /CDrive
put c:\Default.htm

//How I got the -hostkey using WinSCP from client
//”C:\Program Files\WinSCP\” /command

winscp> help
call     Executes arbitrary remote command
cd       Changes remote working directory
chmod    Changes permissions of remote file
close    Closes session
exit     Closes all sessions and terminates the program
get      Downloads file from remote directory to local directory
help     Displays help
keepuptodate Continuously reflects changes in local directory on remote one
lcd      Changes local working directory
lls      Lists the contents of local directory
ln       Creates remote symbolic link
lpwd     Prints local working directory
ls       Lists the contents of remote directory
mkdir    Creates remote directory
mv       Moves or renames remote file
open     Connects to server
option   Sets or shows value of script options
put      Uploads file from local directory to remote directory
pwd      Prints remote working directory
rm       Removes remote file
rmdir    Removes remote directory
session  Lists connected sessions or selects active session
synchronize Synchronizes remote directory with local one
winscp> open
Host: web1
Searching for host…
Connecting to host…
The server’s host key was not found in the cache. You have no guarantee that the
 server is the computer you think it is.

//This is not a internet facing system.  I just wanted to mention. 🙂
The server’s rsa2 key fingerprint is:
ssh-rsa 1024 42:9e:c7:f4:7f:8b:50:10:6a:06:04:b1:d4:f2:04:6d
If you trust this host, press Yes. To connect without adding host key to the cac
he, press No. To abandon the connection press Cancel.
Continue connecting and add host key to the cache?
(Y)es, (N)o, C(a)ncel, (C)opy Key: Cancel


Steve Schofield
Microsoft MVP – IIS