Edit: The issue came about because our machines did not have external IP address and so outgoing traffic was going through Cloud NAT, which was misconfigured (min connections per vm)
I am having issues with a GCP machine being able to connect to an external HTTP server. Below is a line from tcpdump
16:17:26.561616 IP 2.2.2.2 > 3.3.3.3.http: Flags [S], seq 1152634327, win 28400, options [mss1420,sackOK,TS val3415260604 ecr 0,nop,wscale 7], length 0
16:17:26.561736 IP 1.1.1.1 > 2.2.2.2: ICMP host 3.3.3.3 unreachable - admin prohibited filter, length 68
1.1.1.1 is a GCP gateway
2.2.2.2 is my machine on GCP
3.3.3.3 is the external server
How do I know which machine is enforcing the rule that blocks the connection attempt?