Unable to ssh to Debian 9 from 9 or 11
I have three Debian machines on a 192.168.1/24 WiFi network. One is debian 11
and the two others are debian 9. The network is connected, I can ping from any
machine to any other.
The problem is that I can ssh from the debian 9's to the debian 11, but not to
any debian 9, although all the machines can ssh to themselves:
Some ascii art for people with fixed width fonts:
.------OK--->-----debian 11--<--OK------.
| .----<--FAIL---- titan----->--FAIL--. |
| | | |
| v v |
debian 9---------FAIL--->------------debian 9
maria ---------<---FAIL------------kananga
# Debian 9 to debian 11: OK
rprice@kananga:~$ ssh rprice@titan
Linux titan 5.10.0-15-amd64 #1 SMP Debian 5.10.120-1 (2022-06-09) x86_64 ...
# Debian 9 to debian 9: FAIL
rprice@kananga:~$ ssh -v rprice@maria
OpenSSH_7.4p1 Debian-10+deb9u2, OpenSSL 1.0.2l 25 May 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to maria [192.168.1.13] port 22.
debug1: connect to address 192.168.1.13 port 22: Connection timed out
ssh: connect to host maria port 22: Connection timed out
The same problem also exists for port 3493 used for UPS management, with the
same pattern of success and failure between the three machines.
# Debian 9 to debian 11: OK
rprice@kananga:~$ upsc Eaton@titan battery.charge
100
# Debian 9 and 11 to debian 9: FAIL
rprice@kananga:~$ upsc Eaton@maria battery.charge
Error: Connection failure: Connection timed out
rprice@titan /mnt/home upsc Eaton@maria battery.charge
Error: Connection failure: Connection timed out
Any hint or suggestion as to what the problem is would be very welcome, Roger
_____________________________________________________________________________
The debian 9 machines are listening on ports 22 and 3493:
root@maria ~ netstat -pnlt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 822/apache2
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 791/sshd
tcp 0 0 0.0.0.0:3493 0.0.0.0:* LISTEN 1919/upsd
tcp 0 0 0.0.0.0:873 0.0.0.0:* LISTEN 666/rsync
Has systemctl enabled the ssh service?
rprice@kananga:~$ systemctl status ssh
● ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2023-07-14 09:35:17 CEST; 3h 45min ago
Process: 2856 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCESS)
Process: 2848 ExecReload=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Process: 438 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Main PID: 521 (sshd)
Tasks: 1 (limit: 4915)
CGroup: /system.slice/ssh.service
└─521 /usr/sbin/sshd -D
Jul 14 09:51:09 kananga sshd[521]: Received SIGHUP; restarting.
Jul 14 09:51:09 kananga systemd[1]: Reloaded OpenBSD Secure Shell server.
Jul 14 09:51:09 kananga sshd[521]: Server listening on 0.0.0.0 port 22.
Jul 14 10:10:43 kananga sshd[2905]: Accepted password for root from 127.0.0.1 port 50124 ssh2
Jul 14 10:10:43 kananga sshd[2905]: pam_unix(sshd:session): session opened for user root by (uid=0)
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What about ssh from non-Debian? I can ssh to debian 11 from a Samsung
Galaxy Tab S, but not to any debian 9 box.
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