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
  • ik5pvx@lemmy.world
    30·
    2 months ago

    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.

    • gomp@lemmy.mlOP
      5·
      2 months ago

      I did add a bunch of new keys to my ssh agent… this might really be it!

        • gomp@lemmy.mlOP
          3·
          2 months ago

          The ones I added recently are all git-related (one key for signing and I started using different keys for codehaus, gitlab and github)

      • flubba86@lemmy.world
        5·
        2 months ago

        Yep, this is the reason. I have many different identity key files in my ~/.ssh folder, and for some reason ssh always tries all of those first, then exhausts the login tries and doesn’t ask for a password.

        I have the same problem when I specify a specific private key file with -i ./path/to/priv.key. If that key is different than the ones in my .ssh folder, it will use all those first before the specified one, and often exhausts login attempts giving a very hard to diagnose login failure. In that case I need -o IdentitiesOnly yes option to tell ssh to only use the one I specified.

      • cdombroski@programming.devEnglish
        5·
        2 months ago

        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)