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Lately I noticed that when I want to ssh to a server using a password I need to specify -o PubkeyAuthentication=no or I won't be asked for a password and the authentication will fail (well, for all I know, setting some other option may work too).
I use password authentication only once on freshly installed servers/vms, so it's not a huge deal, but... it still bothers me (mainly because I don't remember which option to set).
Do you guys have any idea what it may be?
client's
~/.ssh/config
Host 127.*.*.* 192.168.*.* 10.*.*.* 172.16.*.* 172.17.*.* 172.18.*.* 172.19.*.* 172.2?.*.* 172.30.*.* 172.31.*.*
LogLevel quiet
Stricthostkeychecking no
Userknownhostsfile /dev/null
Host *
ForwardAgent no
AddKeysToAgent no
Compression yes
ServerAliveInterval 10
ServerAliveCountMax 3
HashKnownHosts no
UserKnownHostsFile ~/.ssh/known_hosts
ControlMaster no
ControlPath ~/.ssh/master-%r@%n:%p
ControlPersist no
server's
/etc/ssh/sshd_config (it's from the nixos install iso)
AuthorizedPrincipalsFile none
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
GatewayPorts no
KbdInteractiveAuthentication yes
KexAlgorithms sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
LogLevel INFO
Macs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com
PasswordAuthentication yes
PermitRootLogin yes
PrintMotd no
StrictModes yes
UseDns no
UsePAM yes
X11Forwarding no
Banner none
AddressFamily any
Port 22
Subsystem sftp /nix/store/78mv13w9mgh0s0rd7rnr6ff4d7a39bpd-openssh-9.7p1/libexec/sftp-server
AuthorizedKeysFile %h/.ssh/authorized_keys /etc/ssh/authorized_keys.d/%u
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
Try putting -vvv when you connect and see what's happening. I can imagine this happening if you have multiple identities (private/public key pairs) on the client and you hit a max retry limit. Pub key is always tried first, and it should ask for password once all the local keys have been tried.
I did add a bunch of new keys to my ssh agent... this might really be it!
Having 3 or more identities often causes authentication to fail before it gets around to trying password authentication (or even all the possible keys). Recommend configuring the client to turn off PubkeyAuthentication by default (so that hosts that you don't have a key for will prompt for a password) and specify which key to use on the appropriate hosts using IdentityFile (might need to specifically turn PubkeyAuthentication back on, I don't remember how openssh handles having a default host block with specific host blocks)