Damien Miller wrote:
> On Sun, 20 Oct 2019, Ted Unangst wrote:
> 
> > I have two OpenBSD machines, let's call them laptop and desktop. desktop is 
> > a
> > bit older, and has a ecdsa-sha2-nistp256 key in .ssh/authorized_keys. laptop
> > is configured with a ssh-ed25519 .ssh/id_ed25519 key file. The keyfile has a
> > password and I use ssh-agent and ssh-add to unlock it.
> > 
> > What happens: I ssh from laptop to desktop and ssh asks for the id_ed25519
> > password. This doesn't accomplish much, since it isn't authorized on desktop
> > anyway.
> > 
> > Expected: If the key doesn't work, I should be asked for the remote system
> > password, not the key password. The key has already been unlocked via 
> > ssh-add.
> > 
> > Theory: ssh tries the key, doesn't work, then gets confused when it goes 
> > back
> > into the .ssh for more options and asks to unlock a key it's already seen.
> > 
> > I think this is a regression, I've had similar setup for ages and never
> > noticed this before.
> 
> Could you send the output of "ssh -vvv desktop" from the laptop side?
> Also, what are the permissions for ~/.ssh/id_ed25519*?

Ah, so when this happens, it's on a machine that doesn't have id_ed25519.pub.
Here's a before and after ssh -vvv for reference.

Note that it works fine (without the pub key) connecting to a host that does
have authorized_keys including ed25519.

ativ:~> ssh -vvv 10.3.3.32
OpenSSH_8.1, LibreSSL 3.0.2
debug1: Reading configuration data /home/tedu/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug2: resolve_canonicalize: hostname 10.3.3.32 is address
debug1: auto-mux: Trying existing master
debug1: Control socket "/home/tedu/.ssh/[email protected]:22" does not exist
debug2: ssh_connect_direct
debug1: Connecting to 10.3.3.32 [10.3.3.32] port 22.
debug1: Connection established.
debug1: identity file /home/tedu/.ssh/id_rsa type -1
debug1: identity file /home/tedu/.ssh/id_rsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_dsa type -1
debug1: identity file /home/tedu/.ssh/id_dsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_ecdsa type -1
debug1: identity file /home/tedu/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_ed25519 type -1
debug1: identity file /home/tedu/.ssh/id_ed25519-cert type -1
debug1: identity file /home/tedu/.ssh/id_xmss type -1
debug1: identity file /home/tedu/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.9
debug1: match: OpenSSH_7.9 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 10.3.3.32:22 as 'tedu'
debug3: hostkeys_foreach: reading file "/home/tedu/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file 
/home/tedu/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from 10.3.3.32
debug3: order_hostkeyalgs: prefer hostkeyalgs: 
[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
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,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: 
[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: 
[email protected],aes128-ctr,[email protected]
debug2: ciphers stoc: 
[email protected],aes128-ctr,[email protected]
debug2: MACs ctos: 
[email protected],[email protected],hmac-sha2-256,hmac-sha1
debug2: MACs stoc: 
[email protected],[email protected],hmac-sha2-256,hmac-sha1
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: 
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,diffie-hellman-group14-sha1
debug2: host key algorithms: 
rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
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],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: 
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
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 
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
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: Server host key: ecdsa-sha2-nistp256 
SHA256:UpvWuBaD8CYqnkQgE6dt7VhdMVRYl8qOiwArZ0ngiuI
debug3: hostkeys_foreach: reading file "/home/tedu/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file 
/home/tedu/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from 10.3.3.32
debug1: Host '10.3.3.32' is known and matches the ECDSA host key.
debug1: Found key in /home/tedu/.ssh/known_hosts:5
Host key fingerprint is SHA256:UpvWuBaD8CYqnkQgE6dt7VhdMVRYl8qOiwArZ0ngiuI
+---[ECDSA 256]---+
|. .    .==o ..   |
|.= . . ... ..    |
|*.o + . .. .     |
|o+o+ o o =o      |
|oo.+o = So.      |
|* =..o o.+.      |
|+=.  . .o.       |
|oE.   ...        |
| o               |
+----[SHA256]-----+
debug3: send packet: type 21
debug2: 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: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: [email protected] ED25519 
SHA256:KQM4nnWGRt2PxBx9AZIST6zCR6j4XQAQLSdpRfm9jfg agent
debug1: Will attempt key: /home/tedu/.ssh/id_rsa 
debug1: Will attempt key: /home/tedu/.ssh/id_dsa 
debug1: Will attempt key: /home/tedu/.ssh/id_ecdsa 
debug1: Will attempt key: /home/tedu/.ssh/id_ed25519 
debug1: Will attempt key: /home/tedu/.ssh/id_xmss 
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=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
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,password,keyboard-interactive
debug3: start over, passed a different list 
publickey,password,keyboard-interactive
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: Offering public key: [email protected] ED25519 
SHA256:KQM4nnWGRt2PxBx9AZIST6zCR6j4XQAQLSdpRfm9jfg agent
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
debug1: Trying private key: /home/tedu/.ssh/id_rsa
debug3: no such identity: /home/tedu/.ssh/id_rsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_dsa
debug3: no such identity: /home/tedu/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_ecdsa
debug3: no such identity: /home/tedu/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_ed25519
Enter passphrase for key '/home/tedu/.ssh/id_ed25519': 
debug2: no passphrase given, try next key
debug1: Trying private key: /home/tedu/.ssh/id_xmss
debug3: no such identity: /home/tedu/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug3: send packet: type 50
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
debug3: userauth_kbdint: disable: no info_req_seen
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: 
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
[email protected]'s password: 
debug3: send packet: type 50
debug2: we sent a password packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
Permission denied, please try again.
[email protected]'s password: 

ativ:~> 
ativ:~> 
ativ:~> 
ativ:~> ssh -vvv 10.3.3.32 
OpenSSH_8.1, LibreSSL 3.0.2
debug1: Reading configuration data /home/tedu/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug2: resolve_canonicalize: hostname 10.3.3.32 is address
debug1: auto-mux: Trying existing master
debug1: Control socket "/home/tedu/.ssh/[email protected]:22" does not exist
debug2: ssh_connect_direct
debug1: Connecting to 10.3.3.32 [10.3.3.32] port 22.
debug1: Connection established.
debug1: identity file /home/tedu/.ssh/id_rsa type -1
debug1: identity file /home/tedu/.ssh/id_rsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_dsa type -1
debug1: identity file /home/tedu/.ssh/id_dsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_ecdsa type -1
debug1: identity file /home/tedu/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/tedu/.ssh/id_ed25519 type 3
debug1: identity file /home/tedu/.ssh/id_ed25519-cert type -1
debug1: identity file /home/tedu/.ssh/id_xmss type -1
debug1: identity file /home/tedu/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.9
debug1: match: OpenSSH_7.9 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 10.3.3.32:22 as 'tedu'
debug3: hostkeys_foreach: reading file "/home/tedu/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file 
/home/tedu/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from 10.3.3.32
debug3: order_hostkeyalgs: prefer hostkeyalgs: 
[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
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,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: 
[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: 
[email protected],aes128-ctr,[email protected]
debug2: ciphers stoc: 
[email protected],aes128-ctr,[email protected]
debug2: MACs ctos: 
[email protected],[email protected],hmac-sha2-256,hmac-sha1
debug2: MACs stoc: 
[email protected],[email protected],hmac-sha2-256,hmac-sha1
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: 
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,diffie-hellman-group14-sha1
debug2: host key algorithms: 
rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
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],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: 
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
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 
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
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: Server host key: ecdsa-sha2-nistp256 
SHA256:UpvWuBaD8CYqnkQgE6dt7VhdMVRYl8qOiwArZ0ngiuI
debug3: hostkeys_foreach: reading file "/home/tedu/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file 
/home/tedu/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from 10.3.3.32
debug1: Host '10.3.3.32' is known and matches the ECDSA host key.
debug1: Found key in /home/tedu/.ssh/known_hosts:5
Host key fingerprint is SHA256:UpvWuBaD8CYqnkQgE6dt7VhdMVRYl8qOiwArZ0ngiuI
+---[ECDSA 256]---+
|. .    .==o ..   |
|.= . . ... ..    |
|*.o + . .. .     |
|o+o+ o o =o      |
|oo.+o = So.      |
|* =..o o.+.      |
|+=.  . .o.       |
|oE.   ...        |
| o               |
+----[SHA256]-----+
debug3: send packet: type 21
debug2: 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: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /home/tedu/.ssh/id_ed25519 ED25519 
SHA256:KQM4nnWGRt2PxBx9AZIST6zCR6j4XQAQLSdpRfm9jfg agent
debug1: Will attempt key: /home/tedu/.ssh/id_rsa 
debug1: Will attempt key: /home/tedu/.ssh/id_dsa 
debug1: Will attempt key: /home/tedu/.ssh/id_ecdsa 
debug1: Will attempt key: /home/tedu/.ssh/id_xmss 
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=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
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,password,keyboard-interactive
debug3: start over, passed a different list 
publickey,password,keyboard-interactive
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: Offering public key: /home/tedu/.ssh/id_ed25519 ED25519 
SHA256:KQM4nnWGRt2PxBx9AZIST6zCR6j4XQAQLSdpRfm9jfg agent
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
debug1: Trying private key: /home/tedu/.ssh/id_rsa
debug3: no such identity: /home/tedu/.ssh/id_rsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_dsa
debug3: no such identity: /home/tedu/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_ecdsa
debug3: no such identity: /home/tedu/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/tedu/.ssh/id_xmss
debug3: no such identity: /home/tedu/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug3: send packet: type 50
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: 
publickey,password,keyboard-interactive
debug3: userauth_kbdint: disable: no info_req_seen
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: 
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
[email protected]'s password: 

-rw-------  1 tedu  tedu    484 Mar  1  2019 id_ed25519
-rw-r--r--  1 tedu  tedu    116 Mar  1  2019 id_ed25519.pub

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