Hi Ole, On 28.09.2015 16:29, Ole Reinhardt wrote: > - th = (TCPHDR *) ((char *) ih) + sizeof(IPHDR); > + th = (TCPHDR *) (((char *) ih) + sizeof(IPHDR)); Wow, this one hid for more than 11 years! Btw. most other parts of the stack use this one: th = (TCPHDR *) (ih + 1); Regards, Harald