Read up on MTU (Maximum transmit unit) default for all nets is 1500, meaning packets can not be any greater then 1500 bytes. Also read up on IP flags, there is a no fragmentation flag that you can set. Marek Aditya Pande wrote: > Hi everyone, > > I declared a buffer size of 4096, and in it stored a string of 20 chars. > After that, i sent this packet as an ICMP packet using raw sockets. I am > using the ICMP chk_sum function provided by the object utilities of the > Stevens free code. to this function, you supply a pointer to the start > of the packet, and the length of the packet. When i send this packet > (with check sum put in), i use the sendto() fn. TO my surprise, i found > (using tcpdump) that 3 packets (fragmants) were transmitted. When i > changed the original buffer size to 128, only one packet was sent. > Finally, when i changed the buffer size to 8192, 6 packets were sent. > > Can someone tell me what's going on? In all three cases, i sent the > exact same data of 20 chars. The data is copied into icmp->icmp_data > using strcpy() (which does add a '\0' to terminate the buffer) and use > strlen() to calculate the length of the packet. > > Any suggestions are welcome. > > Sunny days, > Aditya > > - > : send the line "unsubscribe linux-net" in > the body of a message to majordomo@vger.rutgers.edu - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.rutgers.edu
