[Planetlab-users] Raw sockets & TCP

[Guohan Lu]

Hi,

Vitaliy Gleyzer wrote:
> from PlanetLab CVS server, and modified the probe packet to send a SYN, ACK, SYN/ACK, RST, RST/ACK and FIN packets.  It seems the only ones that do not generate an "Operation not permitted" errors are SYN and ACK.
> 
> Could anyone offer any suggestion or experience?
Basically if you want to send a TCP packet, you need emulate the TCP 
setup process, send SYN first, then wait for the SYN/ACK, then send 
data, and finally send RST or FIN. You cannot send data, RST, FIN, 
SYN/ACK without first setup the connection.

If this is not enough to solve your problem, VNET is using Linux iptable
to check if a packet is legitimate or not, the ip_conntrack module to be 
specific. I always find it useful by browsing the ip_conntrack code to 
see why my packet is not permitted.

-Guohan