Tunnel network interface and Sock

[Zhu Ying Jie]

Hi,
   I got several questions about the structures in TCP/IP implementation
in Linux kernel version 2.4.2.
   1. In freebsd, there is structure called "tun_softc" which controls the
interface property of the tunnel network. In Linux, i just found structure
of "net_device" doing same thing for all the network device. I am
wondering if there is some structures which directly controls the tunnel
network instead of the general network device? E.g. I want to get the info
whether the interface has packet in its sending queue.
   2. I am wondering in linux whether ALL the sending or receiving tcp
"sock" are linked together as a link list? And how can I find the first
element in the list?
   Please cc the reply to [e-mail] and thanks a lot for
the help.

Zhu Ying jie
Department of Computer Science,
School of Computing, 
National University of Singapore

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