Software⏱️ 4 min read📅 2026-06-11

How to Fix: Why does adding local IP and username in scp return public key error?

Understanding SCP command behavior with local IP and username.

Quick Answer: The issue arises from the incorrect use of the scp command with a local IP address and username, which is not compatible with the default SCP protocol. Use absolute paths instead.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🚀 How to Resolve This Issue
  3. ✨ Wrapping Up

Adding local IP and username in scp returns public key error because the scp command is attempting to use an SSH connection with authentication, but the destination server does not recognize the source server's identity. This can happen when using SCP with a non-standard port or when the username and IP are specified instead of relying on the default SSH connection.

This issue can be frustrating for users who are familiar with SSH connections, as it requires additional configuration and troubleshooting to resolve. In this guide, we will explore the root causes of this error and provide two primary fix methods to resolve the issue.

⚠️ Common Causes

  • The first main reason why this error happens is that SCP uses a different authentication mechanism than SSH. When you specify a local IP and username with SCP, it attempts to establish an SSH connection using the specified credentials, but the destination server does not recognize the source server's identity because SCP does not use the default SSH port (22) or the SSH protocol's built-in authentication mechanisms.
  • An alternative reason for this error is that the destination server may have specific security policies or configuration settings that restrict access to certain IP addresses or usernames. In such cases, SCP may fail to establish a connection even if the username and IP are correctly specified.

🚀 How to Resolve This Issue

Using SSH with SCP's -N Option

  1. Step 1: To resolve this issue, you can use the -N option with SCP. This option tells SCP to connect to the remote server without attempting to execute a command on the local machine. Instead, it will establish an SSH connection and copy files between the two servers.
  2. Step 2: To do this, modify your scp command to include the -N option: scp -i ~/keyfile -N -r ognjen@100.100.100.1:/path/1/ ognjen@100.100.100.2:/path/2/.
  3. Step 3: By using the -N option, SCP will establish an SSH connection to the destination server and use the specified username and IP for authentication, resolving the public key error.

Using SCP's -o Option with HostKeyAlgorithms

  1. Step 1: Another way to resolve this issue is to specify the hostkey algorithms used by the destination server in the scp command. This can be done using the -o option.
  2. Step 2: To do this, modify your scp command to include the -o option with the HostKeyAlgorithms parameter: scp -i ~/keyfile -r ognjen@100.100.100.1:/path/1/ ognjen@100.100.100.2:/path/2/ -o PubkeyFile=/path/to/public/key/.
  3. Step 3: By specifying the hostkey algorithms, SCP will attempt to use a specific key file for authentication, which may resolve the public key error.

✨ Wrapping Up

In summary, adding local IP and username in scp returns public key error because of differences in authentication mechanisms between SCP and SSH. By using the -N option or specifying hostkey algorithms, you can resolve this issue and successfully copy files between remote servers.

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