VM can't ping the host in VirtualBox host-only networking - virtualbox

Question

My host is MAC OS. In Virtualbox, I create a host-only network whose name is "vboxnet0", where adapter IPv4 address is 192.168.56.1/24, IPv6 disabled and DHCP server disabled.
I have a ubuntu server VM. I enable 2 network adapters for the VM. Adapter1 uses NAT with eth0, Adapter2 uses host-only network "vboxnet0" with eth1. In /etc/network/interfaces, I added the following commands:
auto eth1
iface eth1 inet static
address 192.168.56.50
netmask 255.255.255.0
network 192.168.56.0
broadcast 192.168.56.255
From the host, I can ping the VM; However I can't ping from VM to the host.
Host's routing table
Destination Gateway Flags Refs Use Netif Expire
default 192.168.0.1 UGSc 38 0 en1
127 127.0.0.1 UCS 0 0 lo0
127.0.0.1 127.0.0.1 UH 9 169482 lo0
169.254 link#5 UCS 0 0 en1
192.168.0 link#5 UCS 0 0 en1
192.168.0.1/32 link#5 UCS 1 0 en1
192.168.0.1 84:94:8c:91:1a:f2 UHLWIir 40 25 en1 1194
192.168.0.15/32 link#5 UCS 0 0 en1
192.168.56 link#11 UC 2 0 vboxnet
192.168.56.1 a:0:27:0:0:0 UHLWIi 1 76 lo0
192.168.56.50 8:0:27:9d:5:77 UHLWI 0 5 vboxnet 1084
VM's routing table:
Destination Gateway Genmask Flags Metric Ref Use Iface
default 10.0.2.2 0.0.0.0 UG 0 0 0 eth0
10.0.2.0 * 255.255.255.0 U 0 0 0 eth0
192.168.56.0 * 255.255.255.0 U 0 0 0 eth1
VM's arp table:
Address HWtype HWaddress Flags Mask Iface
192.168.56.1 ether 0a:00:27:00:00:00 C eth1
10.0.2.2 ether 52:54:00:12:35:02 C eth0
192.168.56.1's mac address is the same as the configuration on the host. This info means ARP works.
Start wireshark to listen to the interface "vboxnet0" on the host, I can see ARP received and ICMPs received on the host. ICMP packet says:"Expert Info (Warn/Sequence): No response seen to ICMP request in frame 14" (I can't put the screenshot because of lack of reputation)

Answer 1

Firewall settings.
(I know this is an old question, but I hope this will help anyone reading)
I'm not sure about the firewall setting on MAC OS. But on Windows 10, when I can't ping from a Host to VM but can ping from VM to Host. This is caused by Outbound Firewall rule.
If you don't know which part of which device's firewall to configure, start by disabling the whole thing and go from there.