Hi Thomas, That kind of makes since. I had a customer in CA with a site to site vpn with watch guard and after I had turned off 445 from each end most of the sync stuff disappeared. They also had tons of Trojans that were attacking The gateway! Joseph -----Original Message----- From: Thomas W Shinder [mailto:tshinder@xxxxxxxxxxx] Sent: Wednesday, December 22, 2004 7:19 PM To: [ISAserver.org Discussion List] Subject: [isalist] RE: TCP: Syn Flooding Issue http://www.ISAserver.org Hi Joseph, I'm guessing the problem isn't that the connections are overtaxing the firewall, but that the customer's end of the pipe is full with what is essentially a DDoS. The *only* was to solve the DDoS issue is by having the ISP block the connections from the fat end of the pipe, 'cause there's nothing you can do on your end. The ISP can block via IP address (which gettings pretty hard with DDoS's) but much easier if they're all going for the same port. Tom www.isaserver.org/shinder Tom and Deb Shinder's Configuring ISA Server 2004 http://tinyurl.com/3xqb7 MVP -- ISA Firewalls -----Original Message----- From: josephk [mailto:josephk@xxxxxxxxx] Sent: Wednesday, December 22, 2004 7:22 PM To: [ISAserver.org Discussion List] Subject: [isalist] RE: TCP: Syn Flooding Issue http://www.ISAserver.org Hi Amy, What kind of firewall? Watchguard or something like that? If, it's watchguard you can bock the incoming 445 from The VPN connections and that should eliminate most Of the strange hits. Joseph -----Original Message----- From: Amy Babinchak [mailto:amy@xxxxxxxxxxxxxxxxxxxxxxxxxx] Sent: Wednesday, December 22, 2004 4:36 PM To: [ISAserver.org Discussion List] Subject: [isalist] TCP: Syn Flooding Issue http://www.ISAserver.org I've got an office with tcp syn flooding. It slows the internet down to a crawl and makes accessing secure websites almost impossible. It has this real estate office almost shut down. The weird thing is that the tide goes out of this DOS attack everyday around 4:00. It just stops and then it starts up in the morning. The logs show that the flood is coming from about a dozen IP addresses on the Internet. But is it really? It seems to coincide with the end of work day for about 1/2 of the staff. What's the best way to get rid of a tcp syn flood attack? Should I assume that it's external and not triggered by an internal machine? Wed, 12/22/2004 16:17:44 - TCP connection dropped - Source:66.178.17.36, 53263, WAN - Destination:66.178.207.200, 445, WAN - 'TCP:Syn Flooding' Wed, 12/22/2004 16:17:44 - TCP connection dropped - Source:66.178.17.36, 53263, WAN - Destination:66.178.207.200, 445, WAN - 'TCP:Syn Flooding' Wed, 12/22/2004 16:17:46 - TCP connection dropped - Source:66.178.17.36, 53263, WAN - Destination:66.178.207.200, 445, WAN - 'TCP:Syn Flooding' Wed, 12/22/2004 16:18:26 - TCP connection dropped - Source:220.141.51.234, 3040, WAN - Destination:66.178.207.200, 445, WAN - 'TCP:Syn Flooding' Wed, 12/22/2004 16:18:28 - TCP connection dropped - Source:220.141.51.234, 3040, WAN - Destination:66.178.207.200, 445, WAN - 'TCP:Syn Flooding' FYI: The firewall isn't an ISA Server (working on them to change) and there are 3 VPN connections to other offices on this firewall. If I can get to the bottom of this I'll be the hero and then I can put in some ISA servers. They really need them. They've got site-to-site VPN's, RAS, and Exchange. The place is screaming ISA. Thanks, Amy ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=isalist ISA Server Newsletter: http://www.isaserver.org/pages/newsletter.asp ISA Server FAQ: http://www.isaserver.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: World of Windows Networking: http://www.windowsnetworking.com Leading Network Software Directory: http://www.serverfiles.com No.1 Exchange Server Resource Site: http://www.msexchange.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this ISAserver.org Discussion List as: josephk@xxxxxxxxxxxxxxxxx To unsubscribe visit http://www.webelists.com/cgi/lyris.pl?enter=isalist Report abuse to listadmin@xxxxxxxxxxxxx ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=isalist ISA Server Newsletter: http://www.isaserver.org/pages/newsletter.asp ISA Server FAQ: http://www.isaserver.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: World of Windows Networking: http://www.windowsnetworking.com Leading Network Software Directory: http://www.serverfiles.com No.1 Exchange Server Resource Site: http://www.msexchange.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this ISAserver.org Discussion List as: tshinder@xxxxxxxxxxxxxxxxxx To unsubscribe visit http://www.webelists.com/cgi/lyris.pl?enter=isalist Report abuse to listadmin@xxxxxxxxxxxxx ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=isalist ISA Server Newsletter: http://www.isaserver.org/pages/newsletter.asp ISA Server FAQ: http://www.isaserver.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: World of Windows Networking: http://www.windowsnetworking.com Leading Network Software Directory: http://www.serverfiles.com No.1 Exchange Server Resource Site: http://www.msexchange.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this ISAserver.org Discussion List as: josephk@xxxxxxxxxxxxxxxxx To unsubscribe visit http://www.webelists.com/cgi/lyris.pl?enter=isalist Report abuse to listadmin@xxxxxxxxxxxxx