Linux kernel network debug mode

Hi!

I'm troubleshooting a complicated issue where server replies to one
specific client initial TCP three-way-handshake SYN packet with a long
delay, i.e one can see several TCP SYN packets from the client before
server TCP/IP stack replies with a SYN+ACK. Is it possible to see what
happens with a packet in Linux TCP stack? I checked kernel ring
buffer, but there was nothing interesting/helpful. For example some
network equipment vendors allow one to enable packet tracing which
shows in great detail the day in the life of an packet in device.


thanks,
Martin