Solved ssh works, scp timeout

[MassimoM]

Good morning, i installed two times freebsd release 13, and i have the same problem.
Even when it is freebsd is just installed (no modification to conf files), i can login on this server with ssh, no problem (sometimes it freezes without an apparent reason, i don't know why).
When i try, from a client, to scp, it just doesn't work.
It timeouts.
sometimes it works, but 90% it fails.
In /var/log/auth, i can see the logins from ssh, but nothing about an attempt to scp.
Where am i making the mistake?
i notice that sometimes when i'm logged with ssh on the server, the session "hangs" if i don't use it for a minute or two.
thank you

EDIT: it seems that if a SCP session is running, i can't login with ssh.
if i have a ssh login or a scp running, if i open another ssh, the first hangs.
I set the max connection to 20. nothing happens.

 

[eternal_noob]

freebsd current 13

There is no such thing as FreeBSD 13 CURRENT. CURRENT is/will be 14. Do you use 13.0-RELEASE, 13-STABLE or FreeBSD-CURRENT?

 

[MassimoM]

sorry, i intended "release"

 

[eternal_noob]

Please show the contents of /etc/ssh/sshd_config on the server. Maybe you need to tweak variables like ClientAliveCountMax / ClientAliveInterval / TCPKeepAlive.

See https://unix.stackexchange.com/questions/200239/how-can-i-keep-my-ssh-sessions-from-freezing

 

[MassimoM]

currently is:
Port 22
AddressFamily any
ListenAddress 0.0.0.0
ListenAddress ::

SyslogFacility AUTH
LogLevel INFO


MaxSessions 20
AuthorizedKeysFile .ssh/authorized_keys

i tried to set ClientAliveCountMax / ClientAliveInterval 60 and 60, nothing.

 

[sko]

I've seen similar hicups with borked MTUs in VMs or through (Q-in-Q) tunnels with MTUs set too low at the underlying infrastructure...
Are you using a VPN by any chance?

SSH packets are usually small enough to "just pass through", but scp transfers tend to use the full MTU size.

 

[MassimoM]

I've seen similar hicups with borked MTUs in VMs or through (Q-in-Q) tunnels with MTUs set too low at the underlying infrastructure...
Are you using a VPN by any chance?

SSH packets are usually small enough to "just pass through", but scp transfers tend to use the full MTU size.

no, it is a home server (hp g8 microserver).
the server is connected to vodafone station via copper, no vpn, tunnelling, etc.
i used slackware, debian, oraclelinux, never a single problem about ssh/scp.
it could be a mtu problem if the scp login is established and then the connection fails during transfer, but it timeouts on login.

 

[MassimoM]

Solved.
Just after installing freebsd, i load the firewall script.
For a mistake, i set the maximum ssh connection to "02" instead of "20".

Sorry for wasting your time, i appreciate your help!