>What is pcb?

protocol control block.  i think.  :)

>I've been examining the code in sys/netinet/tcp_input.c and keep coming 
>across pcb, like the findpcb function that locates pcb in a segment.  
>What is it?

i've played around in there too, but not much.  findpcb() will (i
believe) look over the appropriate list of pcb's for a pcb that
matches the current segment (ie, src and dst addr, src and dest port).
it finds a pcb.

>By the way, is there a newsgroup for this, I hate to bug everyone on a 
>mailing list.

there probably is.  i would suggest that comp.protocols.tcp-ip et al,
are probably the closest to what you're looking for.

-- 
|-----< "CODE WARRIOR" >-----|
andrew@echonyc.com (TheMan)        * "ah!  i see you have the internet
codewarrior@daemon.org                               that goes *ping*!"
warfare@graffiti.com      * "information is power -- share the wealth."