Printer FriendlyEmail Article Link

Spirent TestCenter: TCP SYN/ACK number configured to be 0 but always appears as 1 in Wireshark

Environment/Versions
  • Spirent TestCenter, any version
  • Wireshark, any version
Answer
Wireshark behavior:
  • by default, Wireshark reports relative SYN/ACK numbers
  • SYN/ACK number appears as 1 regardless, because it is the first in a TCP session
Way to see actual values:
  • check the real SYN/ACK number in the binary representation of the frame
  • disable relative SYN/ACK numbers in Wireshark to see the actual SYN/ACK number
    • link may change over time

Product : Windows GUI