如何将在 AWS Linux 上运行的 C websocket 服务器与本地虚拟机上的客户端链接？

Question

I recently wrote an echoserver / echoclient program in C for the online class I'm taking (Graduate Introduction to Operating Systems, here ). I was able to complete it with the help of (and modification from Beej's Network guide ( here ). I can run it just fine on my Ubuntu 20.04 virtual machine, running on my Windows 10 laptop. However, I'm trying to run the echoserver on an AWS Linux instance and the echoclient from the Ubuntu VM, as my end goal is building a client program that has a central server data repository. However, I'm running into issues where I start the echoserver C code on the AWS EC2 instance through SSH-ing by PuTTy, then I run the echoclient on the Ubuntu VM, but it can't connect (the error I receive on the client side is that it failed the connect phase of the socket call). I've tried the following steps:

• Editing the inbound rules of the security configuration of the EC2 instance to allow for 'All TCP' connections from the IP address that comes up when I run curl ifconfig.me on my Ubuntu machine
• Changing the network setting of my Ubuntu VM from NAT to Bridged Network
• Testing port access by telnet <AWS Public IP> <PortNo> - which led to "Connection Refused" error
• Ensuring that my outgoing ports aren't blocked by following these instructions

I've looked through the AWS pages ( here ) as well as multiple developer / SO threads (best one I found so far here ) and I just can't seem to figure out out. If anyone could help me out, I'd really appreciate it. I'm happy to post my server & client code if that would be of help.

Answer 1

Figured it out: was missing the following line of code in my server.

hints.ai_flags = AI_PASSIVE;