ExhibitYou are using traceoptions to verify NAT session information on your SRX Series device.

The SRX Series device is performing both source and destination NAT on this session because the traceoptions output shows that both source and destination IP addresses and ports are translated. The source IP address 192.168.5.2 is translated to 192.168.100.1 and the destination IP address 1.1.1.1 is translated to 192.168.5.1. The source port 0 is translated to 14777 and the destination port 80 is translated to 80. The traceoptions output also shows the rule and pool IDs for both source and destination NAT: 2/32770 and 1/1 respectively.

This is the first packet in the session because the traceoptions output shows the flag flow_first_packet, which indicates that this is the first packet of a new session. The traceoptions output also shows the flag flow_first_src_xlate and flow_first_rule_dst_xlate, which indicate that this is the first time that source and destination NAT are applied to this session.

References:

traceoptions (Security NAT) | Junos OS | Juniper Networks

[SRX] How to interpret Flow TraceOptions output for NAT troubleshooting