Traffic rejected on Oracle Cloud (OCI) Connector

Oracle is known to have firewall rule entries by default on the VMs not to forward traffic. You can check this with the following command:

sudo iptables -L -n -v --line-numbers

 
If it has an entry similar to the underlined rules. For example: 

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out source destination 
1 200K 88M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
2 1 84 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 
3 16437 1418K ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 
4 0 0 ACCEPT udp -- * * 0.0.0.0/0 0.0.0.0/0 udp spt:123
5 10 520 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
6 1085 44016 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
7 0 0 ACCEPT all -- tun+ * 0.0.0.0/0 0.0.0.0/0 
8 0 0 ACCEPT all -- tap+ * 0.0.0.0/0 0.0.0.0/0

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out source destination 
1 172 10544 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
2 0 0 ACCEPT all -- tun+ * 0.0.0.0/0 0.0.0.0/0 
3 0 0 ACCEPT all -- tap+ * 0.0.0.0/0 0.0.0.0/0

Chain OUTPUT (policy ACCEPT 175K packets, 189M bytes)
num pkts bytes target prot opt in out source destination 
1 46893 3885K InstanceServices all -- * * 0.0.0.0/0 169.254.0.0/16

Chain InstanceServices (1 references)
num pkts bytes target prot opt in out source destination 
1 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.0.2 owner UID match 0 tcp dpt:3260 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
2 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.2.0/24 owner UID match 0 tcp dpt:3260 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
3 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.4.0/24 owner UID match 0 tcp dpt:3260 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
4 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.5.0/24 owner UID match 0 tcp dpt:3260 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
5 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.0.2 tcp dpt:80 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
6 4834 442K ACCEPT udp -- * * 0.0.0.0/0 169.254.169.254 udp dpt:53 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
7 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.169.254 tcp dpt:53 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
8 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.0.3 owner UID match 0 tcp dpt:80 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
9 0 0 ACCEPT tcp -- * * 0.0.0.0/0 169.254.0.4 tcp dpt:80 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
10 41958 3434K ACCEPT tcp -- * * 0.0.0.0/0 169.254.169.254 tcp dpt:80 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
11 4 1264 ACCEPT udp -- * * 0.0.0.0/0 169.254.169.254 udp dpt:67 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
12 0 0 ACCEPT udp -- * * 0.0.0.0/0 169.254.169.254 udp dpt:69 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
13 97 7372 ACCEPT udp -- * * 0.0.0.0/0 169.254.169.254 udp dpt:123 /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */
14 0 0 REJECT tcp -- * * 0.0.0.0/0 169.254.0.0/16 tcp /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */ reject-with tcp-reset
15 0 0 REJECT udp -- * * 0.0.0.0/0 169.254.0.0/16 udp /* See the Oracle-Provided Images section in the Oracle Cloud Infrastructure documentation for security impact of modifying or removing this rule */ reject-with icmp-port-unreachable

 
Then, you will have a block message (ICMP Host prohibited) on the traffic passing the Connector:
 

 

You can proceed to remove these rules using the following commands:

sudo iptables -D InstanceServices 15 && sudo iptables -D InstanceServices 14

sudo iptables -D FORWARD 1

sudo iptables -D INPUT 6

Note: The command shown may require modification for your scenario. For further reference, find the rule number with this information: