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A user-mode TCP/IP stack based on linux tap device.

  • ❗ It's not a production-ready networking stack, only my practical project after learning network stack.
  • 📝 If you have already learned the TCP/IP stack and want to


  • linux tun/tap device (/dev/net/tun exists if supported)
  • pthreads

Quick start

$ make
# ./tapip                    (run as root)
[net shell]: ping   (ping linux kernel TCP/IP stack)
(waiting icmp echo reply...)
[net shell]: help            (see all embedded commands)

The corresponding network topology is here: network topology (2).

More information for hacking TCP/UDP/IP/ICMP:
See doc/net_topology, and select a script from doc/test to do.

Socket Api

_socket,_read,_write,_send,_recv,_connect,_bind,_close and _listen are provided now.
Three socket types(SOCK_STREAM, SOCK_DGRAM, SOCK_RAW) can be used.
You can use these apis to write applications working on tapip.
Good examples are app/ping.c and app/snc.c.

How to implement

I refer to xinu and Linux 2.6.11 TCP/IP stack and use linux tap device to simulate net device(for l2).
A small shell is embedded in tapip.
So this is just user-mode TCP/IP stack :)

Any use

Tapip makes it easy to hack TCP/IP stack, just compiling it to run.
It can also do some network test: arp snooping, proxy, and NAT!
I think the most important is that tapip helps me learn TCP/IP, and understand linux TCP/IP stack.


You can refer to saminiir/level-ip and its blog posts for more details.


user-mode TCP/IP stack based on linux tap device






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