Hi,
I attached a Second ENI to my Ubuntu OS machine on AWS VPC, the internal IP of this new ENI is 192.168.12.24. When I try to SSH in to this machine from another machine in the same VPC I get a connection time out. I am able to SSH in to the first ENI of the same machine both from inside and from outside the VPC.

Route command shows the following:
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 * 255.255.240.0 U 0 0 0 eth0
192.168.0.0 * 255.255.240.0 U 0 0 0 eth1
default 192.168.0.1 0.0.0.0 UG 100 0 0 eth0

I am new in the field of iptable and iproutes, any help would be great.
Thanks

It seems, something is wrong with your networking, There is no route to 192.168.12.0 network. Both Nic destined to same network i.e 192.168.0.0. Due to many abbreviations confusion is there. Please make it more clear. I dont know what is AWS, VPC and ENI..??

My apologies for using the abbreviations, AWS is amazon web services, VPC is virtual private cloud and ENI is elastic network interface.
Both the network interfaces I am talking are part of the same subnet in one VPC. The address range for this subnet is 192.168.0.0/16.
Please let me know if you have any more questions.

Routing table does not showing any entry for 192.168.12.0 network. Can you show your interfaces file.?

Yes it does, look at the netmask.

@OP: Could you supply the IP Addresses of your first ENI and relevant other hosts you are using?

According to my understanding, if machine has IP address 192.168.12.24. Routing table should show related entry something like..