如何向同一主机发送HTTPS GET请求并指定目标IP？

Great question! Since you already have the HTTP case working by specifying the host header alongside an IP-based URL, HTTPS needs a small adjustment because of SSL certificate validation—certificates are tied to domain names, not raw IP addresses. Let’s break down how to make this work with HTTPoison:

The Core Issue #

If you tried using https://104.16.110.208/ with a Host header directly, HTTPoison would reject the connection. That’s because the SSL certificate for digitalocean.com doesn’t match the IP address in the URL. Instead, we need to:

1. Use the actual domain in the request URL (so certificate validation passes)
2. Force the underlying socket to connect to your manually chosen IP address

Working Code Example #

# Pick your target IP from the dig results
target_ip = "104.16.110.208"
# The domain the SSL certificate is issued for
target_domain = "digitalocean.com"

# Convert the IP string to an Erlang-style tuple (required for socket options)
ip_tuple = target_ip |> String.split(".") |> Enum.map(&String.to_integer/1) |> List.to_tuple()

# Send the HTTPS request
case HTTPoison.get("https://#{target_domain}/", [], 
  transport_options: [
    socket_opts: [
      {:inet, :addr, ip_tuple} # Force connection to this specific IP
    ]
  ]
) do
  {:ok, response} -> IO.inspect(response.status_code)
  {:error, reason} -> IO.inspect(reason)
end

How This Works #

• We use https://digitalocean.com as the URL, so HTTPoison automatically validates the SSL certificate against the domain (no certificate errors)
• The transport_options[:socket_opts][{:inet, :addr, ip_tuple}] tells the underlying Erlang socket to connect directly to your chosen IP, skipping standard DNS resolution for the domain
• The Host header is automatically set to digitalocean.com from the URL, so the server knows which virtual host to route the request to

Custom Host Header (If Needed) #

If you need to specify a custom Host header (like www.digitalocean.com instead of the root domain), just add it to the headers list:

HTTPoison.get("https://#{target_domain}/", [{"Host", "www.digitalocean.com"}], 
  transport_options: [
    socket_opts: [
      {:inet, :addr, ip_tuple}
    ]
  ]
)

IPv6 Notes #

If you’re working with IPv6 addresses, convert the string to an Erlang tuple using :inet.parse_address/1 instead:

{:ok, ip_tuple} = :inet.parse_address("2604:a880:400:d1::891:6001")

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