TCP top

Just like top, but for TCP sockets.

Requirements

Relies on the ss command to work, so only expect it to work on Linux. Other than that, you need Python 2.7, which should also be easily available.

Download and install

The following script will automatically download and install tcptop in ~/bin/tcptop-x.y.z:

bash <(curl -s https://raw.githubusercontent.com/luciopaiva/tcptop/master/install.sh)

retries.sh

Python script to list TCP clients having retransmission problems (from a Linux server standpoint). The scripts probes the ss command to obtain the data and then sorts connections by last ACK time, oldest first.

The script shows several fields (the screenshot above shows only a few), but the most important are:

• LastACK: elapsed time since the last ACK was received from that client (the table is sorted by this field)
• Backoff: I called this so because that's how ss calls it, but this is how many retransmissions (aka retries) have been tried since the last ACK was received from the client. By default, Linux retries 15 times before finally giving up on a connection
• Timer: how long until the current retransmission attempt times out. A timeout happens in case the ACK is not received. If that happens, the Backoff counter will increase by one and a new timer will begin

For descriptions about the other fields, check the source code.

The Alias column is just something to help the human eye track a connection as it moves up the table (we are not good at reading IPs).

How to run:

./retries.sh PORT

Where PORT is an optional port to filter the results. Pass nothing to have no filter applied.

txbuffers.sh

Script to help identify sockets with largest the transmission buffers currently connected.

./txbuffers.sh PORT

Acknowledgements

I am using a list of names taken from this project (license here).