Hi Viacheslav.
- I can’t ping dgw, but I think it is normal, no one of my GCP instances (Linux & Windows) can ping dgw.
- I will run dmesg in a bit and submit it as separate replay (i just restarted the system).
- for the “before the problem” output below I added ping 10.150.0.10 with show arp so you can visualise that ARP is not resolving for LAN units (10.150.0.10 is one of my lan units with no OS firewall or an other protection).
- Finally: the rest of requested info is below: (disregard dum interfaces created only for VPN testing purposes).
== after the problem ===
adm@rtr1:~$ ping 8.8.8.8
connect: Network is unreachable
adm@rtr1:~$ sh ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
F - PBR, f - OpenFabric,
> - selected route, * - FIB route
C>* 10.150.0.0/20 is directly connected, eth0, 09:08:51
K>* 10.150.0.1/32 [0/0] is directly connected, eth0, 09:08:55
C * 10.150.0.5/32 is directly connected, eth0, 09:08:57
C>* 10.150.0.5/32 is directly connected, eth0, 09:08:57
C>* 192.168.7.0/24 is directly connected, dum7, 09:08:51
C>* 192.168.8.0/24 is directly connected, dum8, 09:08:51
adm@rtr1:~$ sh arp
Address HWtype HWaddress Flags Mask Iface
10.150.0.11 (incomplete) eth0
10.150.0.1 ether 42:01:0a:96:00:01 C eth0
10.150.0.10 (incomplete) eth0
adm@rtr1:~$ sudo arp -an
? (10.150.0.11) at on eth0
? (10.150.0.1) at 42:01:0a:96:00:01 [ether] on eth0
? (10.150.0.10) at on eth0
adm@rtr1:~$ sudo netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
10.150.0.0 0.0.0.0 255.255.240.0 U 0 0 0 eth0
10.150.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.7.0 0.0.0.0 255.255.255.0 U 0 0 0 dum7
192.168.8.0 0.0.0.0 255.255.255.0 U 0 0 0 dum8
adm@rtr1:~$ sudo ip r
10.150.0.0/20 dev eth0 proto kernel scope link src 10.150.0.5
10.150.0.1 dev eth0 scope link
192.168.7.0/24 dev dum7 proto kernel scope link src 192.168.7.1
192.168.8.0/24 dev dum8 proto kernel scope link src 192.168.8.1
adm@rtr1:~$ sudo ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc pfifo_fast state UP group default qlen 1000
link/ether 42:01:0a:96:00:05 brd ff:ff:ff:ff:ff:ff
inet 10.150.0.5/32 brd 10.150.0.5 scope global eth0
valid_lft forever preferred_lft forever
inet 10.150.0.5/20 brd 10.150.15.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::4001:aff:fe96:5/64 scope link
valid_lft forever preferred_lft forever
3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether d2:da:37:23:e9:b2 brd ff:ff:ff:ff:ff:ff
4: dum7: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether 5e:59:92:b4:c4:b2 brd ff:ff:ff:ff:ff:ff
inet 192.168.7.1/24 brd 192.168.7.255 scope global dum7
valid_lft forever preferred_lft forever
inet6 fe80::5c59:92ff:feb4:c4b2/64 scope link
valid_lft forever preferred_lft forever
5: dum8: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether da:d7:c6:8a:b1:52 brd ff:ff:ff:ff:ff:ff
inet 192.168.8.1/24 brd 192.168.8.255 scope global dum8
valid_lft forever preferred_lft forever
inet6 fe80::d8d7:c6ff:fe8a:b152/64 scope link
valid_lft forever preferred_lft forever
== before the problem ===
adm@rtr1:~$ show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
F - PBR, f - OpenFabric,
> - selected route, * - FIB route
K * 0.0.0.0/0 [0/0] via 10.150.0.1, eth0 inactive, 00:02:39
C>* 10.150.0.0/20 is directly connected, eth0, 00:02:34
K>* 10.150.0.1/32 [0/0] is directly connected, eth0, 00:02:39
C * 10.150.0.5/32 is directly connected, eth0, 00:02:40
C>* 10.150.0.5/32 is directly connected, eth0, 00:02:41
C>* 192.168.7.0/24 is directly connected, dum7, 00:02:34
C>* 192.168.8.0/24 is directly connected, dum8, 00:02:34
adm@rtr1:~$ show arp
Address HWtype HWaddress Flags Mask Iface
10.150.0.1 ether 42:01:0a:96:00:01 C eth0
adm@rtr1:~$ sudo arp -an
? (10.150.0.1) at 42:01:0a:96:00:01 [ether] on eth0
adm@rtr1:~$ sudo netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 10.150.0.1 0.0.0.0 UG 0 0 0 eth0
10.150.0.0 0.0.0.0 255.255.240.0 U 0 0 0 eth0
10.150.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.7.0 0.0.0.0 255.255.255.0 U 0 0 0 dum7
192.168.8.0 0.0.0.0 255.255.255.0 U 0 0 0 dum8
adm@rtr1:~$ sudo ip r
default via 10.150.0.1 dev eth0
10.150.0.0/20 dev eth0 proto kernel scope link src 10.150.0.5
10.150.0.1 dev eth0 scope link
192.168.7.0/24 dev dum7 proto kernel scope link src 192.168.7.1
192.168.8.0/24 dev dum8 proto kernel scope link src 192.168.8.1
adm@rtr1:~$ sudo ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc pfifo_fast state UP group default qlen 1000
link/ether 42:01:0a:96:00:05 brd ff:ff:ff:ff:ff:ff
inet 10.150.0.5/32 brd 10.150.0.5 scope global eth0
valid_lft forever preferred_lft forever
inet 10.150.0.5/20 brd 10.150.15.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::4001:aff:fe96:5/64 scope link
valid_lft forever preferred_lft forever
3: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 1e:c6:06:40:da:a7 brd ff:ff:ff:ff:ff:ff
4: dum7: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether e2:04:f9:24:49:90 brd ff:ff:ff:ff:ff:ff
inet 192.168.7.1/24 brd 192.168.7.255 scope global dum7
valid_lft forever preferred_lft forever
inet6 fe80::e004:f9ff:fe24:4990/64 scope link
valid_lft forever preferred_lft forever
5: dum8: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether 42:b6:7f:d2:f7:2d brd ff:ff:ff:ff:ff:ff
inet 192.168.8.1/24 brd 192.168.8.255 scope global dum8
valid_lft forever preferred_lft forever
inet6 fe80::40b6:7fff:fed2:f72d/64 scope link
valid_lft forever preferred_lft forever
admin@rtr1:~ ping 10.150.0.10
PING 10.150.0.10 (10.150.0.10) 56(84) bytes of data.
From 10.150.0.5 icmp_seq=1 Destination Host Unreachable
From 10.150.0.5 icmp_seq=2 Destination Host Unreachable
From 10.150.0.5 icmp_seq=3 Destination Host Unreachable
^C
--- 10.150.0.10 ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3066ms
pipe 4
adm@rtr1:~ sudo arp -an
? (10.150.0.10) at on eth0
? (10.150.0.1) at 42:01:0a:96:00:01 [ether] on eth0
adm@rtr1:~$ sho arp
Address HWtype HWaddress Flags Mask Iface
10.150.0.10 (incomplete) eth0
10.150.0.1 ether 42:01:0a:96:00:01 C eth0