From: "Dagamier *" <zayasj@hotmail.com>

On Fri, 12 Dec 1997, Lasher <wolf@wolf.mudservices.com> wrote:

>From my experience of syn floods they dont 'lag' a mud. The main 
>symptom is that the mud is running just fine, people are playing
>away quite happily, yet, no-one else can establish a new connection.
>Have never heard of syn floods causing a mud to lag bigtime, if I 
>am wrong then please correct me.. :)


Sorry it's taken so long to respond. Anyways, what you said Lasher is 
mostly true. In most cases it "shouldn't" lag a mud but it can due to 
the way that TCP connections are made. The following is a brief report I 
gave to my boss while I was working on setting up some security issues 
where I work. Please this is for informational purposes and I assume no 
responsibility for those who want to use this in a destructive nature. 
'Nuff said.

SYN Flood:  A standard TCP connection is established by sending a SYN 
packet to the destination host.  The destination host then sends a 
SYN/ACK packet to the sending host.  Now the sender sends a SYN/ACK back 
to the destination and a connection is established.  Now, here is where 
the part about lagging comes in.  Every system has a set amount of 
memory set aside to deal with all incoming connections. Depending on how 
big this chunck of memory is and if your machine is really a unix 
machine and not an x86 flavor of unix, an attacker can potentially cause 
your system to crawl by continuously send you SYN packets.  This will 
cause all the memory set aside for establishing connections to be 
exhausted thereby, as Lasher said, disallowing any more connections to 
be made. The other side effect is that if enough of these packets are 
sent it can cause your system to slow down especially if your CPU is 
doubling as part of your network management and also dependent on the 
amount of memory that your system has set aside to establish these 
connections.

Hope this information is useful and if you have any more Unix related 
questions feel free to ask. It's what I do for a living anyway and I 
enjoy mudding too much to see it pissed away by people attacking sites.  

Happy Mudding

Dagamier of "A Merging of Fates"