From: grahn+nntp@snipabacken.se   
      
   On Tue, 08 Sep 2009 09:08:26 -0400, Roy Smith  wrote:   
   > In article   
   > ,   
   >  David Schwartz  wrote:   
   >   
   >> On the Internet, a lot of connections pass through firewalls and   
   >> transparent proxies that find it very hard to DTRT with half-open TCP   
   >> connections.   
      
   Ok. But note that at least some of the earlier discussion applied to   
   "fully open" TCP connections too -- ones which simply had no data   
   going in one of the directions.   
      
   > This is a specific case of the more general statement, "This which are not   
   > commonly used tend to be broken".  Forget about firewalls, I wouldn't be   
   > surprised if you found kernels which can't handle simplex connections.   
   > It's just not something that's commonly done, so it doesn't get a lot of   
   > testing.   
   >   
   > We've found the same is true for TCP urgent (i.e. "out of band") data.  I'm   
   > currently working on an application which depends on OOB data to implement   
   > keepalive messages.  In theory, the design is fine.  The problem is, we   
   > keep running into real-life examples of systems with broken   
   > implementations.  Not to mention that the security world seems to have   
   > gotten into its head that urgent data is a security issue and we're seeing   
   > firewalls which are administratively configured to block any TCP packet   
   > with the urgent bit set.   
   >   
   > Bottom line: stick to the mainstream features, because they're more likely   
   > to work in the real world.   
      
   I won't argue against that ... but I note that there is another   
   way to think about it:   
      
   "Don't work around broken routers, IP stacks or muddy security   
   reasoning. Place the blame where it belongs, because otherwise pretty   
   soon we'll all have to use XML-RPC to port 80 for everything."   
      
   /Jorgen   
      
   --   
     // Jorgen Grahn    O  o   .   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)