How did I mess up receiving UDP datagrams?
by mikedodd from LinuxQuestions.org on (#523FS)
I just installed Debian 10 (buster) on a home server, and migrated everything from the old server to it.
I have a solar power system that transmits UDP datagrams. A C program on the server receives these and populates a MySQL (MariaDB) database. This program has been working for 8 years on the old box and now on the new box. Until yesterday.
The new server had local Ethernet connectivity, but no Internet connectivity. On the LAN it shared drives with Samba, ping worked, SSH worked, and it until yesterday it received the UDP packets. Just no Internet.
My routing table had no default route, so I thought that be the reason the box had no Internet. Yesterday I used route to add a default gateway. After I did this, the C program no longer received any UDP packets -- it sits in a loop waiting for a packet from the solar power system.
My routing table currently looks like this (my router has static IP .55, and the solar power system is .66):
Code:Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.55 0.0.0.0 UG 0 0 0 eno1
192.168.1.0 192.168.1.55 255.255.255.0 UG 0 0 0 eno1
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eno1Without the default route, the Internet was not available. After I added the default route, the UDP packets stopped flowing.
But I deleted the default route, and again no Internet as expected. But the UDP packets still weren't coming through. I added the default route again to get to the Internet.
I even issued route -host 192.168.1.66 to describe a route directly to the the solar power system, but that made no difference.
I'm lost. Can anyone suggest how I can get the UDP packets flowing again>
Thanks very much.
--- Mike
I have a solar power system that transmits UDP datagrams. A C program on the server receives these and populates a MySQL (MariaDB) database. This program has been working for 8 years on the old box and now on the new box. Until yesterday.
The new server had local Ethernet connectivity, but no Internet connectivity. On the LAN it shared drives with Samba, ping worked, SSH worked, and it until yesterday it received the UDP packets. Just no Internet.
My routing table had no default route, so I thought that be the reason the box had no Internet. Yesterday I used route to add a default gateway. After I did this, the C program no longer received any UDP packets -- it sits in a loop waiting for a packet from the solar power system.
My routing table currently looks like this (my router has static IP .55, and the solar power system is .66):
Code:Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.55 0.0.0.0 UG 0 0 0 eno1
192.168.1.0 192.168.1.55 255.255.255.0 UG 0 0 0 eno1
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eno1Without the default route, the Internet was not available. After I added the default route, the UDP packets stopped flowing.
But I deleted the default route, and again no Internet as expected. But the UDP packets still weren't coming through. I added the default route again to get to the Internet.
I even issued route -host 192.168.1.66 to describe a route directly to the the solar power system, but that made no difference.
I'm lost. Can anyone suggest how I can get the UDP packets flowing again>
Thanks very much.
--- Mike