SSH port mapping connection keeps being reset

Question

I just installed some updates on my EC2 instance, and now I can't maintain an SSH port remapping connection. How can I deal with this?

What I'm seeing, every 15-30 minutes or so:
```
PS C:\Users
icho> ssh ec2-user@44.234.21.89 -NL 1234:localhost:1234
client_loop: send disconnect: Connection reset
```

I also have other terminal windows just logged in to the same server without port forwarding, and they don't get disconnected.

I acknowledge that the updates might be a red herring, but not sure what else changed.

Updates that were installed:
```
Removed:
  kernel.x86_64 0:4.14.138-114.102.amzn2                  kernel-devel.x86_64 0:4.14.219-164.354.amzn2

Installed:
  kernel.x86_64 0:4.14.262-200.489.amzn2                  kernel-devel.x86_64 0:4.14.262-200.489.amzn2

Updated:
  ca-certificates.noarch 0:2021.2.50-72.amzn2.0.3             ec2-net-utils.noarch 0:1.6-1.amzn2
  ec2-utils.noarch 0:1.2-46.amzn2                             kernel-headers.x86_64 0:4.14.262-200.489.amzn2
  kernel-tools.x86_64 0:4.14.262-200.489.amzn2                openssh.x86_64 0:7.4p1-22.amzn2.0.1
  openssh-clients.x86_64 0:7.4p1-22.amzn2.0.1                 openssh-server.x86_64 0:7.4p1-22.amzn2.0.1
```

Answer

I'm having a similar problem.

On Monday (2/28), we noticed only a few ssh connections would actually connect. Once connected, the connection is stable. Running tcptrack on our bastion host in aws, and trying to ssh into the bastion host on its external interface (internal is fine), we see the connections are being "RESET" on the bastion side.

This was not a problem on Friday and is a problem on Monday (and still on going).

I'd estimate that only about 20% of connection attempts work.

I have verified we are nowhere near our port cap on the bastion host.

If you find a solution, please share.

SSH port mapping connection keeps being reset

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