Why setting host github.com is fine, but host GitHub isn't

[Saltsmart]

I've created a ed25519 file C:/Users/Administrator/.ssh/id_GitHub, with C:/Users/Administrator/.ssh/config:

Host github.com
    HostName github.com
    User git
    IdentityFile C:/Users/Administrator/.ssh/id_GitHub
    IdentitiesOnly yes

ssh -T [email protected] returns Hi Saltsmart! You've successfully authenticated, but GitHub does not provide shell access..
It's OK!

But when I change the Host (alias?) in C:/Users/Administrator/.ssh/config:

Host GitHub
    HostName github.com
    User git
    IdentityFile C:/Users/Administrator/.ssh/id_GitHub
    IdentitiesOnly yes

ssh -T [email protected] returns [email protected]: Permission denied (publickey)..

[Saltsmart]

OpenSSH_for_Windows_9.5p2, LibreSSL 3.8.2
debug1: Reading configuration data C:\\Users\\Administrator/.ssh/config
debug3: Failed to open file:C:/ProgramData/ssh/ssh_config error:2
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> 'C:\\Users\\Administrator/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> 'C:\\Users\\Administrator/.ssh/known_hosts2'
debug2: resolving "github.com" port 22
debug3: resolve_host: lookup github.com:22
debug3: ssh_connect_direct: entering
debug1: Connecting to github.com [20.205.243.166] port 22.
debug1: Connection established.
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_rsa error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_rsa.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_rsa error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_rsa type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_rsa-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_rsa-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_rsa-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_rsa-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ecdsa error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ecdsa type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ecdsa-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ecdsa-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ecdsa_sk type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ecdsa_sk-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ecdsa_sk-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519 error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ed25519 error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ed25519 type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ed25519-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ed25519-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ed25519_sk type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_ed25519_sk-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_ed25519_sk-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_xmss error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_xmss.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_xmss error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_xmss type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_xmss-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_xmss-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_xmss-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_xmss-cert type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_dsa error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_dsa.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_dsa error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_dsa type -1
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_dsa-cert error:2
debug3: Failed to open file:C:/Users/Administrator/.ssh/id_dsa-cert.pub error:2
debug3: failed to open file:C:/Users/Administrator/.ssh/id_dsa-cert error:2
debug1: identity file C:\\Users\\Administrator/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_for_Windows_9.5
debug1: Remote protocol version 2.0, remote software version 1a4a900
debug1: compat_banner: no match: 1a4a900
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to github.com:22 as 'git'
debug3: record_hostkey: found key type ED25519 in file C:\\Users\\Administrator/.ssh/known_hosts:4
debug3: record_hostkey: found key type RSA in file C:\\Users\\Administrator/.ssh/known_hosts:5
debug3: record_hostkey: found key type ECDSA in file C:\\Users\\Administrator/.ssh/known_hosts:6
debug3: load_hostkeys_file: loaded 3 keys from github.com
debug3: Failed to open file:C:/Users/Administrator/.ssh/known_hosts2 error:2
debug1: load_hostkeys: fopen C:\\Users\\Administrator/.ssh/known_hosts2: No such file or directory
debug3: Failed to open file:C:/ProgramData/ssh/ssh_known_hosts error:2
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts: No such file or directory
debug3: Failed to open file:C:/ProgramData/ssh/ssh_known_hosts2 error:2
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts2: No such file or directory
debug3: order_hostkeyalgs: have matching best-preference key type [email protected], using HostkeyAlgorithms verbatim
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c,[email protected]
debug2: host key algorithms: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],rsa-sha2-512,rsa-sha2-256
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: sntrup761x25519-sha512,[email protected],curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,[email protected]
debug2: host key algorithms: ssh-ed25519,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],[email protected],[email protected],aes256-ctr,aes192-ctr,aes128-ctr
debug2: ciphers stoc: [email protected],[email protected],[email protected],aes256-ctr,aes192-ctr,aes128-ctr
debug2: MACs ctos: [email protected],[email protected],hmac-sha2-512,hmac-sha2-256
debug2: MACs stoc: [email protected],[email protected],hmac-sha2-512,hmac-sha2-256
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug3: kex_choose_conf: will use strict KEX ordering
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ssh-ed25519 SHA256:+DiY3wvvV6TuJJhbpZisF/zLDA0zPMSvHdkr4UvCOqU
debug3: record_hostkey: found key type ED25519 in file C:\\Users\\Administrator/.ssh/known_hosts:4
debug3: record_hostkey: found key type RSA in file C:\\Users\\Administrator/.ssh/known_hosts:5
debug3: record_hostkey: found key type ECDSA in file C:\\Users\\Administrator/.ssh/known_hosts:6
debug3: load_hostkeys_file: loaded 3 keys from github.com
debug3: Failed to open file:C:/Users/Administrator/.ssh/known_hosts2 error:2
debug1: load_hostkeys: fopen C:\\Users\\Administrator/.ssh/known_hosts2: No such file or directory
debug3: Failed to open file:C:/ProgramData/ssh/ssh_known_hosts error:2
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts: No such file or directory
debug3: Failed to open file:C:/ProgramData/ssh/ssh_known_hosts2 error:2
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts2: No such file or directory
debug1: Host 'github.com' is known and matches the ED25519 host key.
debug1: Found key in C:\\Users\\Administrator/.ssh/known_hosts:4
debug3: send packet: type 21
debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
debug2: ssh_set_newkeys: mode 1
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: ssh_packet_read_poll2: resetting read seqnr 3
debug1: SSH2_MSG_NEWKEYS received
debug2: ssh_set_newkeys: mode 0
debug1: rekey in after 134217728 blocks
debug3: ssh_get_authentication_socket_path: path '\\\\.\\pipe\\openssh-ssh-agent'
debug3: unable to connect to pipe \\\\.\\pipe\\openssh-ssh-agent, error: 2
debug1: get_agent_identities: ssh_get_authentication_socket: No such file or directory
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_rsa
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_ecdsa
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_ecdsa_sk
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_ed25519
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_ed25519_sk
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_xmss
debug1: Will attempt key: C:\\Users\\Administrator/.ssh/id_dsa
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa>
debug1: kex_ext_info_check_ver: [email protected]=<0>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_rsa
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_rsa: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_ecdsa
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_ecdsa_sk
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_ecdsa_sk: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_ed25519
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_ed25519_sk
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_ed25519_sk: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_xmss
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_xmss: No such file or directory
debug1: Trying private key: C:\\Users\\Administrator/.ssh/id_dsa
debug3: no such identity: C:\\Users\\Administrator/.ssh/id_dsa: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
[email protected]: Permission denied (publickey).

When using ssh -vvvT [email protected]

[ellebrink]

Hey, the Host in your SSH config is what you use in your command. When you changed it to Host GitHub, you need to run

ssh -T git@GitHub

(not [email protected]).

If you want both to work, use:

Host GitHub github.com
    HostName github.com
    User git
    IdentityFile C:/Users/Administrator/.ssh/id_GitHub

The Host line is basically the alias/pattern that SSH looks for when you type your command.

[Saltsmart]

Thanks to @ellebrink and @luke21678-eng❤️, so why linking to GitHub behaves different from linking to an IP?

For example, I have a server aaa.bbb.ccc.ddd:

Host Server
    HostName aaa.bbb.ccc.ddd
    User name

ssh -T [email protected] will successfully match the HostName, not Host.
I have checked the manual and ChatGPT, it's still not clear.

[ellebrink]

You're welcome @Saltsmart! Feel free to accept my answer above so other users with the same problem can easily find it.

As for your other question: actually, ssh [email protected] is not matching your Host Server entry. It's just connecting directly to the IP without using your config at all. SSH doesn't need a config file to connect to an address.

The Host directive only matches what you type in the command. From the manual: "matched against the host name given on the command line".

To use your Host Server config, you'd need to run ssh Server (then it applies the HostName, User, etc.).

Both GitHub and your IP work the same way: Host is always a pattern matcher for what you type, never for the HostName value.

[Saltsmart]

It seems HostName is never used as matcher, just for re-location after the entry is matched.
ssh -T [email protected] still needs password, so I should believe the config entry is not used.