SSH shows 'type -1' when it cannot find or load an identity file. This usually means the key file doesn't exist at the specified path or cannot be read. While often a harmless informational message, it indicates SSH is falling back to other authentication methods.
The 'type -1' message in SSH output indicates that SSH failed to load an identity file from the specified path. SSH probes for various key types in default locations (id_rsa, id_dsa, id_ecdsa, id_ed25519, and their corresponding certificate files). When a file is not found or cannot be read, SSH assigns it type -1 to indicate the probe failed. This is different from type 0 (RSA), type 1 (DSA), type 3 (ECDSA), etc., which indicate successfully loaded keys. The message appears during SSH debug output (-vvv flag) and is typically benign when it occurs for certificate files or key types you don't use, but becomes problematic when it occurs for the key you're actually trying to use for authentication.
Verify the key file exists at the path shown in the error message:
ls -la /home/user/.ssh/id_rsaIf the file doesn't exist, you'll see 'No such file or directory'. You can list all SSH keys in your ~/.ssh directory:
ls -la ~/.sshSSH requires specific file permissions to work correctly:
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_rsa
chmod 644 ~/.ssh/id_rsa.pubPrivate keys must be readable only by the owner (600). If permissions are wrong, SSH will skip the key and try others.
If the key file doesn't exist, generate a new key pair:
ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa -N ""For modern systems, Ed25519 keys are preferred:
ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519 -N ""During generation, you'll be prompted for a passphrase. Press Enter to skip it for passwordless authentication.
If you have multiple keys and want to use a specific one, tell SSH which identity file to use:
ssh -i ~/.ssh/id_rsa -o IdentitiesOnly=yes user@hostnameThe -o IdentitiesOnly=yes flag prevents SSH from offering other identities, which can reduce authentication attempts and type -1 messages.
If you're using an SSH config file (~/.ssh/config), verify the IdentityFile paths:
cat ~/.ssh/configIf any IdentityFile lines reference non-existent paths, either create the keys or remove/comment out those lines:
Host example.com
User myuser
IdentityFile ~/.ssh/id_rsa
# IdentityFile ~/.ssh/id_ed25519 # Remove if this file doesn't existTo understand which keys SSH is trying and why type -1 appears, use verbose mode:
ssh -vvv user@hostnameThis shows each identity file SSH probes, the result for each, and why it failed. Lines with 'type -1' indicate the file wasn't found or couldn't be loaded. Lines with 'type 0' or higher indicate the file was successfully loaded.
The 'type -1' message is normal and expected for SSH certificate files (like id_rsa-cert.pub) if you don't use SSH certificates. Certificate files are optional and most users only have standard key pairs. Type -1 is also expected for key types you haven't generated (e.g., type -1 for id_dsa if you only use RSA keys). SSH first tries to load the public key part of the certificate; if it doesn't exist, it gets type -1 and SSH continues to the next probe. This is the intended behavior and not a problem. The issue only becomes critical if the specific key you're trying to authenticate with shows type -1, which means SSH couldn't load it and will fail authentication unless another valid method is available.
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