Re: [SLUG] iptables and session affinity

[James Morris <jmorris@xxxxxxxxxxxxxxxx>]

On Tue, 26 Feb 2002, David Peterson wrote:

> 
> Hi All,
> 
> I have a question regarding iptables and session affinity, which some of 
> you may know as "sticky sessions".
> 
> I believe for example that the linux virtual server (LVS) project 
> supports load-balancing via NAT with session affinity. What this 
> basically means is that I can have a linux box running LVS sitting in 
> front of (say) 3 web server boxes, and when a new connection comes in, 
> LVS routes it to one box for the entirety of the session - so cookies, 
> session beans under JSP (tomcat) etc are all preserved. With regular 
> round-robin load balancing or similar this is not the case, and plays 
> havoc with session-driven websites as I am sure you all can understand.
> 
> In LVS, the sticky session load balancing is accessed via the "ipvsadm" 
> command from what I am led to believe. (I think the "-i" option but I am 
> not sure).

AFAIK, this is only layer-4 persistence (i.e. TCP connection, not 
cookies).

> What I want to know is whether session affinity (sticky session) support 
> is available in iptables?

No.

This would require reconstructing, parsing and tracking HTTP exchanges in 
the kernel -- I'm not aware of anyone working on it at this stage.


- James
-- 
James Morris
<jmorris@xxxxxxxxxxxxxxxx>