Solved

Sonicwall - NSA 2400 TCP Handshake Violation

Posted on 2013-11-04
3
8,411 Views
Last Modified: 2013-11-08
Good morning,
I have a Sonciwall NSA 2400 with multiple Sub Interfaces/VLAN's.  One of these VLAN's hosts an WIN2K8 RDS Server.  When users logon and try to access the internet, loads of the below errors get logged on the Sonicwall.  The users web connections never resolve properly.  

We have tried.

 1.  Turning off TCP timeout.
 2.  Disable Content Filtering


Any ideas?

1      11/04/2013 11:11:21.384      Debug      Network      TCP packet received on non-existent/closed connection; TCP packet dropped      20.0.201.8, 51782, X2:V201      207.240.254.97, 443, X1      TCP Flag(s): ACK              
2      11/04/2013 11:10:21.192      Debug      Network      TCP packet received on non-existent/closed connection; TCP packet dropped      20.0.201.8, 51746, X2:V201      207.240.254.97, 443, X1      TCP Flag(s): ACK              
3      11/04/2013 11:08:51.704      Debug      Network Access      Broadcast packet dropped      20.0.201.8, 0, X2:V201      20.0.201.255, 20584      Protocol:137              
4      11/04/2013 11:05:56.128      Notice      Network Access      TCP handshake violation detected; TCP connection dropped      20.0.201.8, 51604, X2:V201      192.168.0.23, 8059, X1      Handshake Timeout              
5      11/04/2013 11:05:43.880      Debug      Network Access      Broadcast packet dropped      20.0.201.8, 0, X2:V201      20.0.201.255, 20584      Protocol:137              
6      11/04/2013 11:04:51.160      Notice      Network Access      TCP handshake violation detected; TCP connection dropped      20.0.201.8, 51563, X2:V201      192.168.20.27, 445, X1      Handshake Timeout              
7      11/04/2013 11:04:39.544      Debug      Network      TCP packet received on non-existent/closed connection; TCP packet dropped      20.0.201.8, 51316, X2:V201      143.166.83.190, 80, X1      TCP Flag(s): ACK              
8      11/04/2013 11:03:01.112      Notice      Network Access      TCP handshake violation detected; TCP connection dropped      20.0.201.8, 51499, X2:V201      192.168.0.23, 8059, X1      Handshake Timeout              
9      11/04/2013 11:02:59.144      Debug      Network      TCP packet received on non-existent/closed connection; TCP packet dropped      20.0.201.8, 51449, X2:V201      64.18.20.10, 80, X1      TCP Flag(s): ACK
0
Comment
Question by:GeminiTechnology
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 25

Accepted Solution

by:
Diverse IT earned 500 total points
ID: 39621678
Hi GeminiTechnology,

What is the SonicOS firmware version? (you most likely need to upgrade your firmware)
Have you performed any hardening on the security appliance?
What type of WAN connection is being used?

This Log message is displayed when the SonicWALL firewall receives a TCP packet after a particular connection was closed.

This is a generic error message as there are a number of root causes that can create this error. For example: A packet was delayed in transition for some reason and reaches the SonicWALL after the connection was closed. The SonicWALL Firewall drops the packet and logs the message.

Login to the SonicWALL and go to Firewall Settings > Flood Protection then match the following settings:
Under TCP Settings
• Enforce strict TCP compliance with RFC 793 and RFC 1122: Uncheck
        • Enable TCP handshake enforcement: Uncheck
• Enable TCP checksum enforcement: Uncheck
• Enable TCP handshake timeout: Uncheck
Layer 3 SYN Flood Protection - SYN Proxy
• SYN Flood Protection Mode: select Watch and report possible SYN floods
Then re-test with new connections (terminating the old ones by closing the browsers).

If that still fails to resolve, follow below:
Increase the Inactivity timeout of the rules on the SonicWALL.
VPN tunnels: You may need to increase activity timeout on the LAN to VPN as well as the VPN to LAN rule to avoid timeout conditions.
Make sure the upstream device, source and destination computers connecting to each other do not have latency.

Let me know how it goes and please answer the above questions in the interim.
Thanks!
0
 

Author Closing Comment

by:GeminiTechnology
ID: 39633304
Thank you!
0
 
LVL 25

Expert Comment

by:Diverse IT
ID: 39634254
You're welcome! Glad I could help...thanks for the points!
0

Featured Post

Get MongoDB database support online, now!

At Percona’s web store you can order your MongoDB database support needs in minutes. No hassles, no fuss, just pick and click. Pay online with a credit card. Handle your MongoDB database support now!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When it comes to security, there are always trade-offs between security and convenience/ease of administration. This article examines some of the main pros and cons of using key authentication vs password authentication for hosting an SFTP server.
Use of TCL script on Cisco devices:  - create file and merge it with running configuration to apply configuration changes
Viewers will learn how to connect to a wireless network using the network security key. They will also learn how to access the IP address and DNS server for connections that must be done manually. After setting up a router, find the network security…
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…
Suggested Courses

627 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question