PowerShell连接OCI Linux实例报错No such host is known排查求助

Let's break down the issues you're facing step by step—this is a common set of pitfalls when setting up SSH access to OCI instances, so we'll cover all the likely culprits:

1. SSH命令语法错误（最直接的触发点） #

Your command ssh -i'x''y' has a critical syntax issue:

• The -i flag requires a space between itself and the private key path. The correct format should be ssh -i "完整私钥路径" opc@<实例公网IP>
• By writing 'x''y' without separation, you're telling SSH to treat the combined string as the private key file path, which doesn't exist. This directly causes the "No such host is known" error, as the system misinterprets your target address as part of the key path.

2. Invalid or Unbound Public IP #

• First, confirm the public IP you're using is an Elastic IP (EIP) properly bound to your instance's VNIC: OCI Linux instances don't get a public IP by default—you have to create an EIP and attach it manually. Using a private IP or an unbound EIP will never work for public access.
• Check your instance status: Ensure it's in the Running state. If it's stopped or terminating, the public IP will be unreachable.

3. Missing Network Security Rules #

This is the most common reason for OCI instance connectivity failures:

• Inbound Rules: The Network Security Group (NSG) or Security List attached to your subnet needs two rules:
  • Allow ICMP protocol (for ping tests) with source 0.0.0.0/0 (or your local public IP for tighter security)
  • Allow TCP port 22 (SSH) with the same source range
• Double-check that these rules are applied to the correct subnet/VNIC—OCI's default security settings block all inbound public traffic by default.

4. Incorrect Route Table Configuration #

The route table linked to your subnet must include a default route (0.0.0.0/0) pointing to the Internet Gateway (IGW). Without this route, even if security rules allow traffic, your instance can't communicate with the public internet at all.

5. Local Network Restrictions #

• Check your local firewall: It might be blocking outbound SSH (port 22) or ICMP traffic. Temporarily disable it for testing if possible.
• Proxy interference: If you're using a corporate or personal proxy, SSH might not be configured to route through it. Try disabling the proxy temporarily to rule this out.
• ISP limitations: Some ISPs block port 22 by default. If this is the case, you can either switch to a different port (not ideal for security) or use OCI's Bastion Service to access your instance without opening SSH directly to the public.

内容的提问来源于stack exchange，提问作者yaya30001996