The Industrial Raspberry Pi Forum

Dear Sir or Madams,

I have problems to connnect to Rasperry Pis with SSH.

When the Rasperries are directly through a switch connected to my device the ssh connection works. So the SSH-configuration of my Raspberries should be right.
If I want to connect them through a VLAN (so without routing) it just partly works.
If I want to connect through a firewall from another network the ssh-connection doesn't work. A trace of the firewall shows that my Raspberries (e.g. IP adress: 10.44.110.50) do not answer to arp-requests.

Here the results of the firewall trace:
"
A-DE-LAU-DCNFG01M (lan) $ diagnose sniffer packet any 'host 10.44.110.50' 4 0 a
interfaces=[any]
filters=[host 10.44.110.50]
2019-07-11 11:09:51.935769 port17 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:09:51.935770 lag3 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:09:51.935788 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:09:52.931746 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:09:53.931882 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:09:54.940344 port17 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:09:54.940346 lag3 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:09:54.940352 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:09:55.932159 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:09:56.932298 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:10:00.938033 port17 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:10:00.938035 lag3 in 10.44.14.93.49253 -> 10.44.110.50.22: syn 1968618601
2019-07-11 11:10:00.938042 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:10:01.933000 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
2019-07-11 11:10:02.933142 port16 out arp who-has 10.44.110.50 tell 10.44.110.8
"

The Raspberry (Jessie Debian as OS) has an static ip-adress which is configured in /etc/dhcpcd.conf
The configuration is (also se appendix):
IP-Adress: 10.44.110.50/ 25
Gateway: 10.44.110.8


This looks like an arp-problem, but I can say within the VLAN it is possible to connect to this Raspberry from different other devices. So this looks like that arp ist working.
Maybe arp does not work reliable. I don't know and do not have any clue, what the problem could be.

Can anyone help me. If you need further information, please do not hesitate to aks.

Best regards and thanks in advance

Tobi

Maybe your firewall blocks ICMP?

The Raspberries do not have any firewall.
The firewall is configared that ICMP and SSH is allowed.

Do you work with RaspberryPis or RevolutionPis? If you are working with VLANs do you have the chance to debug your Trunk ports?