Charles Green's questions

I've set up an Azure Application Gateway with Azure Kubernetes Service using the Azure Application Gateway Ingress Controller (AGIC) and confirmed that it's working correctly using the sample guestbook app.

I then used almost the exact configuration to deploy a Golang app that uses the gRPC-gateway to the same AKS cluster.

The default liveness and readiness health checks fail so I've configured custom exec based (not fit for prod) so that they pass the checks and are added to the backend pool.

The gateway (REST) pod is healthy however the pod that uses gRPC is still unhealthy and has the following error message.

Cannot connect to server. Check whether any NSG/UDR/Firewall is blocking 
access to server. Check if application is running on correct port.

I'm guessing that the gateway doesn't support gRPC/binary communication but I'm not positive and cannot find anything in the documentation.

Setup Details: - Greenfield - Application Gateway Ingress Controller tutorial to build the AKS cluster

I've submitted a help ticket to Microsoft however I'm still waiting for a reply. Has anyone else tried to host gRPC apps using the Application Gateway?

I am trying to step up port forwarding from port 25 to port 2025 on the same AWS EC2 Ubuntu 14.04 instance using iptables. I am using port 2025 to receive income emails using Alfresco.

The first step I took was to open port 25 for INBOUND traffic in the Security Group using the AWS Console. Next I followed the following steps using a new EC2 Ubuntu instance. My understanding is that the first command allows inbound traffic to port 25. The second command then forwards the traffic from port 25 to port 2025 and then the last step saves (but does not persist the settings).

sudo iptables -A INPUT -p tcp --dport 25 -j ACCEPT
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 25 -j REDIRECT --to-port 2025
sudo iptables-save

I've confirmed that Alfresco is listening on port 2025 and the iptable settings using the following commands:

bitnami@ip-172-30-0-000:~$ netstat -an | grep 25

tcp6       0      0 :::2025                 :::*                    LISTEN   


bitnami@ip-172-30-0-000:~$ sudo iptables -t nat -L -n -v
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source    destination         
0     0 REDIRECT   tcp  --  eth0   *       0.0.0.0/0    0.0.0.0/0    tcp dpt:25 redir ports 2025

Chain INPUT (policy ACCEPT 0 packets, 0 bytes) 
pkts bytes target     prot opt in     out     source    destination         

Chain OUTPUT (policy ACCEPT 5 packets, 431 bytes)
pkts bytes target     prot opt in     out     source    destination         

Chain POSTROUTING (policy ACCEPT 5 packets, 431 bytes)
pkts bytes target     prot opt in     out     source    destination  

When testing the connection with telnet I would expect something like the following however now the connection simply times out.

Expecting:

Trying 54.85.10.9...
Connected to 54.163.62.000.
Escape character is '^]'.
220 simplycubedholdings.com ESMTP SubEthaSMTP 3.1.6
421 Timeout waiting for data from client.

Actual:

telnet 54.163.62.000 25
Trying 54.163.62.000...
telnet: connect to address 54.163.62.000: Operation timed out
telnet: Unable to connect to remote host

Any help or direction would be greatly appreciated.

Many thanks,

Charles