We are given a pcap for this challenge. We can see there are two hosts communicating with each other and  `10.19.31.85` looks like it's the host sending messages to the PLC at `192.168.110.40`
If we look at all the ACK packets coming from `10.19.31.85` there is some interesting padding at the end of the packet that looks like it follows the format `<sequence#>:<data>`. If we extract the padding data and put it in order we get the flag.
```text1:MAPNA{y2:0U_sHOu3:Ld_4lW44:yS__CaR5:3__PaAD6:d1n9!!}
MAPNA{y0U_sHOuLd_4lW4yS__CaR3__PaADd1n9!!}
```