title: ESP protocol packet doesn't show payload information while transferring data after IPsec tunnel creation using strongswan
body: <p>We have created Ipsec tunnel using strong-swan as follows,</p>
  
  <p>server (eth interface- 13.13.7.13)  --> clinet (eth interface - 13.13.7.18)</p>
  
  <p>when ikev2 phase1 and phae2 messages exchanges happens, source IP  and destination IP are same as IP address assigned to eth interfaces. (confirmed via wire-shark). And ISAKMP message exchange has been done successfully.</p>
  
  <p>1) When I started transmitting data via SCP protocol between client &amp; sever , I have noticed ESP and SSH packets.
     In which ESP packets just have sequence number but not encrypted payload and SSH  packets have encrypted payload. But as per Ipsec protocol data should be encrypted in ESP protocol itself. why there is no payload info in ESP packets ?</p>
  
  <p>FI : I noticed continuous ESP packets after ISAKMP exchange (negotiation and authentication done)</p>
  
  <p>SSH and ESP Packets look like below:</p>
  
  <pre><code>   **SSH Protocol** 
      SSH Version 2 (encryption:chacha20-poly1305@openssh.com mac:&lt;implicit&gt; compression:none)
      Packet Length (encrypted): e78d1cd9
      Encrypted Packet: 9679398c167c33ca6c1eecc4879e59d417b39545c80b0e40...
      MAC: 27b594b6290dcdf3a09fd2fb84884cd7
  
     **ESP Protocol**
     Encapsulating Security Payload
     ESP SPI: 0xc86cb75d (3362568029)
     ESP Sequence: 19
  </code></pre>