Once the server agrees to take part in the connection, the server will return a SYN-ACK and wait for a final ACK to start the connection.
In frame 2, you will see the field values, which are similar, although the acknowledgment number has changed. The sequence and acknowledgment numbers in frame 2 are as follows:
- Sequence number: 0 (relative sequence number)
- Acknowledgment number: 1
In addition, the TCP flags are now set to SYN-ACK, as shown in the following screenshot:
TCP SYN-ACK flags set
Before any data is exchanged, the handshake must complete with the acknowledgment packet, as discussed next.
