I have linux system which is connected to the internet via an lte modem and I am communicating with it via modemManager. So I am having a little bit of difficulty in understanding the number of data bytes consumed.
root@raspberrypi-cm3:~# mmcli -b 0
-------------------------
Status | connected : 'yes'
| suspended : 'no'
| interfaces: 'wwan0'
| IP timeout: '20'
-------------------------
Properties | apn: 'myapn'
| roaming: 'allowed'
| IP type: 'none'
| user: 'none'
| password: 'none'
| number: 'none'
-------------------------
Stats | Duration: '105060'
| Bytes received: '6300'
| Bytes transmitted: '6209'
root@raspberrypi-cm3:~# ping -c 1 -s 0 www.opendns.com
8 bytes from ****.****.****.*** seq =0 ttl=50
1 packet transmitted, 1 packet received, 0% packet loss
root@raspberrypi-cm3:~# mmcli -b 0
-------------------------
Status | connected : 'yes'
| suspended : 'no'
| interfaces: 'wwan0'
| IP timeout: '20'
-------------------------
Properties | apn: 'myapn'
| roaming: 'allowed'
| IP type: 'none'
| user: 'none'
| password: 'none'
| number: 'none'
-------------------------
Stats | Duration: '105090'
| Bytes received: '6512'
| Bytes transmitted: '6359'
So according to modem manager. I am consuming 150 bytes of data to send a ping to opendns and I am receiving 212 bytes of data?
But how is this possible. I am transmitting 8 bytes and receiving 8 bytes with ICMP header the total will be 16 bytes of data received.
Can someone explain me where are these addition data bytes coming from? Are they simply an over-head when I am communicating with my nameserver? If thats an over-head is there some sort of formula that I can use to calculate the approximate data consumed?
My end goal is just to cross-verify the total data bytes consumed
I found my answer by using
tcpdump
to create a pcap file. Thanks for down voting my question and not providing any answer. For other beginners like me. If you are facing a similar problem. Please usetcpdump
this will give you an detailed explanation on packets sent and received by your device.