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[Bug 3056] New: A non-idle sesstion always be terminated when set ClientAliveCountMax to 0

Bug ID: 3056
Summary: A non-idle sesstion always be terminated when set
ClientAliveCountMax to 0
Product: Portable OpenSSH
Version: 8.0p1
Hardware: amd64
OS: Linux
Status: NEW
Severity: enhancement
Priority: P5
Component: sshd

The issue exists from version 7.6p1.
reproduce steps:
1) set sshd_config:
ClientAliveInterval 60
ClientAliveCountMax 0

2) user ssh login, then compile our project, the compile time will take
more than 60 seconds:

[abel@AbelCentOS75 ~/build/Cloud/Agent/linux]$make
starting to compile...
<a lot of output>
Connection to localhost closed.
===> the session get closed unexpectly after 60 seconds.

I understand that with ClientAliveCountMax == 0 there will be no
"client alive packet"sent and the client ssh session will be terminated
after ClientAliveInterval seconds of idle time.

But in my use case, the client session keep receiving data from server
side, is it still an "idle" session? the user experience is terrible.

after dig into it, I found the behavior change since 7.6p1 is from

before 7.6p1, if there are any incomming or outgoing traffic from ssh
client side, sshd think the connection is not idle.

after 7.6p1, only if there are any incomming traffic from ssh client,
sshd think it's not idle.

Also, for the reason why I set the ClientAliveCountMax to 0, it is
recommended by "CIS CentOS Linux 7 Benchmark", you can get the content
easily from here:

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