What is the meaning of all nettop column names?

Question

Created Jan ’16

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I"m trying to troubleshoot some network issues and am running nettop to monitor live tcp traffic. My question is that I cannot find any documentation relating to the displayed column names. For example, what is rx ooo, or tx cwin? I can guess but would rather not assume anything. The man page is of no help and Googling has yet to return anything.

Thanks in advance!

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Answer 1

jiacai2050 OP

Mar ’18

Is there anyone knowing this ?

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Answer 2

DTS Engineer OP

Apple

Mar ’18

I’m not a

nettop

expert but it’s likely that:

```
rx_ooo
```
means “received out of order”
```
tx_cwin
```
means “transmit congestion window”

In situations like this I generally follow the breadcrumb trail from the tool’s source code in Darwin to the fundamental implementation within the kernel. Unfortunately that’s not possible in this case because

nettop

is not open source. Given that, my recommendation is that you file a bug agains the man page asking for a better explanation of the columns. Please post your bug number, just for the record.

Still, getting a better description of the column names won’t necessarily help. To make sense of values like this you really need to understand the ins and outs of TCP. My go-to reference for this sort of thing is TCP/IP Illustrated by Stevens.

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