Created attachment 3214 [details]
Output of scp -v -v -v

scp cannot transfer large files (multi gigabyte) reliably from the server to the client. The client always dies in mid-transfer with the message:

  ssh_dispatch_run_fatal: Connection to 11.22.33.44 port 33333: message authentication code incorrect
  lost connection

In my case, the server is an Ubuntu 18.04 VM on Linode, and the client is an Ubuntu 16.04 workstation. The problem occurs with the supplied 16.04 ssh client (OpenSSH_7.2p2) as well as the latest hand-compiled OpenSSH client (OpenSSH_7.9p1).

Server version information:

$ uname -a
Linux myhost 4.18.16-x86_64-linode118 #1 SMP PREEMPT Mon Oct 29 15:38:25 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

$ ssh -V
OpenSSH_7.6p1 Ubuntu-4ubuntu0.1, OpenSSL 1.0.2n  7 Dec 2017

Client version information:

$ uname -a
Linux example 4.4.0-139-generic #165-Ubuntu SMP Wed Oct 24 10:58:50 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

$ ssh -V
OpenSSH_7.9p1, OpenSSL 1.0.2g  1 Mar 2016

The only options in my ~/.ssh/config (other than User and HostName and Port) were:

 Protocol 2
 StrictHostKeyChecking yes
 ForwardAgent no

Attached is the (sanitized) output of:

$ scp -v -v -v myhost:mydir/myfile .  2> logfile.txt