[Bug 3615] Host Based Authentication is failing

bugzilla-daemon at mindrot.org bugzilla-daemon at mindrot.org
Fri Sep 22 11:12:51 AEST 2023 

https://bugzilla.mindrot.org/show_bug.cgi?id=3615

--- Comment #12 from Richard Kreutzer <tunerooster at gmail.com> ---
OK, for the sake of simplicity, I have tested with rsa only...

Here is basement-gentoo:/etc/ssh/ssh_host_rsa_key.pub

basement-gentoo.krautclan.com ssh-rsa
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
root at basement-gentoo


Here is gemini:/etc/ssh/ssh_known_hosts

basement-gentoo.krautclan.com ssh-rsa
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
root at basement-gentoo

Running this on basement-gentoo:

ssh -p 1023 -o PreferredAuthentications=hostbased gemini pwd 

And this on gemini:

/usr/sbin/sshd -dddep 1023

I get this from the server debug output:


debug3: fd 4 is not O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug3: send_rexec_state: entering fd = 7 config len 3337
debug3: ssh_msg_send: type 0
debug3: send_rexec_state: done
debug1: rexec start in 4 out 4 newsock 4 pipe -1 sock 7
debug3: recv_rexec_state: entering fd = 5
debug3: ssh_msg_recv entering
debug3: recv_rexec_state: done
debug2: parse_server_config_depth: config rexec len 3337
debug3: rexec:15 setting AddressFamily inet
debug3: rexec:19 setting HostKey /etc/ssh/ssh_host_rsa_key
debug3: rexec:20 setting HostKey /etc/ssh/ssh_host_dsa_key
debug3: rexec:21 setting HostKey /etc/ssh/ssh_host_ecdsa_key
debug3: rexec:22 setting HostKey /etc/ssh/ssh_host_ed25519_key
debug3: rexec:34 setting PermitRootLogin yes
debug3: rexec:53 setting HostbasedAuthentication yes
debug3: rexec:54 setting HostbasedUsesNameFromPacketOnly yes
debug3: rexec:58 setting IgnoreRhosts no
debug3: rexec:66 setting ChallengeResponseAuthentication no
debug3: rexec:87 setting UsePAM yes
debug3: rexec:92 setting X11Forwarding yes
debug3: rexec:93 setting X11DisplayOffset 10
debug3: rexec:94 setting X11UseLocalhost yes
debug3: rexec:96 setting PrintMotd no
debug3: rexec:97 setting PrintLastLog no
debug3: rexec:114 setting Subsystem sftp       
/usr/lib64/misc/sftp-server
debug3: rexec:124 setting AcceptEnv LANG LC_*
debug3: rexec:126 setting UseDNS yes
debug1: sshd version OpenSSH_9.4, OpenSSL 3.1.2 1 Aug 2023
debug1: private host key #0: ssh-rsa
SHA256:RBjUkH7i6jeYKf3M6UdiArktuWuxFQxkbbd3RNkYmTc
debug1: private host key #1: ssh-dss
SHA256:QCavFBV4tIu+5+hai4IGqFZIF1hxkCTsagLiE05LlkQ
debug1: private host key #2: ecdsa-sha2-nistp256
SHA256:kJT1D+9lFXkt7xG/8Ix1eHQx0SYVqyU5K+euSHHX+vE
debug1: private host key #3: ssh-ed25519
SHA256:sHM5dcf+1bWQpNjiA5x+kkhWpMO5EdMIfh7TqeTHcY8
debug1: inetd sockets after dupping: 3, 3
debug3: process_channel_timeouts: setting 0 timeouts
debug3: channel_clear_timeouts: clearing
Connection from 192.168.1.17 port 46500 on 192.168.1.101 port 1023
rdomain ""
debug1: Local version string SSH-2.0-OpenSSH_9.4
debug1: Remote protocol version 2.0, remote software version
OpenSSH_9.4
debug1: compat_banner: match: OpenSSH_9.4 pat OpenSSH* compat
0x04000000
debug2: fd 3 setting O_NONBLOCK
debug3: ssh_sandbox_init: preparing seccomp filter sandbox
debug2: Network child is on pid 18370
debug3: preauth child monitor started
debug3: privsep user:group 22:22 [preauth]
debug1: permanently_set_uid: 22/22 [preauth]
debug3: ssh_sandbox_child: setting PR_SET_NO_NEW_PRIVS [preauth]
debug3: ssh_sandbox_child: attaching seccomp filter program [preauth]
debug3: append_hostkey_type: ssh-rsa key not permitted by
HostkeyAlgorithms [preauth]
debug3: append_hostkey_type: ssh-dss key not permitted by
HostkeyAlgorithms [preauth]
debug1: list_hostkey_types:
rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug3: send packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT sent [preauth]
debug3: receive packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT received [preauth]
debug2: local server KEXINIT proposal [preauth]
debug2: KEX algorithms:
sntrup761x25519-sha512 at openssh.com,curve25519-sha256,curve25519-sha256 at libssh.org,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
[preauth]
debug2: host key algorithms:
rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug2: ciphers ctos:
chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
[preauth]
debug2: ciphers stoc:
chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
[preauth]
debug2: MACs ctos:
umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
[preauth]
debug2: MACs stoc:
umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
[preauth]
debug2: compression ctos: none,zlib at openssh.com [preauth]
debug2: compression stoc: none,zlib at openssh.com [preauth]
debug2: languages ctos:  [preauth]
debug2: languages stoc:  [preauth]
debug2: first_kex_follows 0  [preauth]
debug2: reserved 0  [preauth]
debug2: peer client KEXINIT proposal [preauth]
debug2: KEX algorithms:
sntrup761x25519-sha512 at openssh.com,curve25519-sha256,curve25519-sha256 at libssh.org,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
[preauth]
debug2: host key algorithms:
ssh-ed25519-cert-v01 at openssh.com,ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,sk-ssh-ed25519-cert-v01 at openssh.com,sk-ecdsa-sha2-nistp256-cert-v01 at openssh.com,rsa-sha2-512-cert-v01 at openssh.com,rsa-sha2-256-cert-v01 at openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519 at openssh.com,sk-ecdsa-sha2-nistp256 at openssh.com,rsa-sha2-512,rsa-sha2-256
[preauth]
debug2: ciphers ctos:
chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
[preauth]
debug2: ciphers stoc:
chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
[preauth]
debug2: MACs ctos:
umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
[preauth]
debug2: MACs stoc:
umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
[preauth]
debug2: compression ctos: none,zlib at openssh.com,zlib [preauth]
debug2: compression stoc: none,zlib at openssh.com,zlib [preauth]
debug2: languages ctos:  [preauth]
debug2: languages stoc:  [preauth]
debug2: first_kex_follows 0  [preauth]
debug2: reserved 0  [preauth]
debug1: kex: algorithm: sntrup761x25519-sha512 at openssh.com [preauth]
debug1: kex: host key algorithm: ssh-ed25519 [preauth]
debug1: kex: client->server cipher: chacha20-poly1305 at openssh.com MAC:
<implicit> compression: none [preauth]
debug1: kex: server->client cipher: chacha20-poly1305 at openssh.com MAC:
<implicit> compression: none [preauth]
debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
debug3: receive packet: type 30 [preauth]
debug1: SSH2_MSG_KEX_ECDH_INIT received [preauth]
debug3: mm_sshkey_sign: entering [preauth]
debug3: mm_request_send: entering, type 6 [preauth]
debug3: mm_sshkey_sign: waiting for MONITOR_ANS_SIGN [preauth]
debug3: mm_request_receive_expect: entering, type 7 [preauth]
debug3: mm_request_receive: entering [preauth]
debug3: mm_request_receive: entering
debug3: monitor_read: checking request 6
debug3: mm_answer_sign: entering
debug3: mm_answer_sign: ssh-ed25519 KEX signature len=83
debug3: mm_request_send: entering, type 7
debug2: monitor_read: 6 used once, disabling now
debug3: send packet: type 31 [preauth]
debug3: send packet: type 21 [preauth]
debug2: ssh_set_newkeys: mode 1 [preauth]
debug1: rekey out after 134217728 blocks [preauth]
debug1: SSH2_MSG_NEWKEYS sent [preauth]
debug1: Sending SSH2_MSG_EXT_INFO [preauth]
debug3: send packet: type 7 [preauth]
debug1: expecting SSH2_MSG_NEWKEYS [preauth]
debug3: receive packet: type 21 [preauth]
debug1: SSH2_MSG_NEWKEYS received [preauth]
debug2: ssh_set_newkeys: mode 0 [preauth]
debug1: rekey in after 134217728 blocks [preauth]
debug1: KEX done [preauth]
debug3: receive packet: type 5 [preauth]
debug3: send packet: type 6 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user rwk service ssh-connection method
none [preauth]
debug1: attempt 0 failures 0 [preauth]
debug3: mm_getpwnamallow: entering [preauth]
debug3: mm_request_send: entering, type 8 [preauth]
debug3: mm_getpwnamallow: waiting for MONITOR_ANS_PWNAM [preauth]
debug3: mm_request_receive_expect: entering, type 9 [preauth]
debug3: mm_request_receive: entering [preauth]
debug3: mm_request_receive: entering
debug3: monitor_read: checking request 8
debug3: mm_answer_pwnamallow: entering
debug3: Trying to reverse map address 192.168.1.17.
debug2: parse_server_config_depth: config reprocess config len 3337
debug3: mm_answer_pwnamallow: sending MONITOR_ANS_PWNAM: 1
debug3: mm_request_send: entering, type 9
debug2: monitor_read: 8 used once, disabling now
debug3: process_channel_timeouts: setting 0 timeouts [preauth]
debug3: channel_clear_timeouts: clearing [preauth]
debug2: input_userauth_request: setting up authctxt for rwk [preauth]
debug3: mm_start_pam entering [preauth]
debug3: mm_request_send: entering, type 100 [preauth]
debug3: mm_inform_authserv: entering [preauth]
debug3: mm_request_send: entering, type 4 [preauth]
debug2: input_userauth_request: try method none [preauth]
debug3: user_specific_delay: user specific delay 0.000ms [preauth]
debug3: ensure_minimum_time_since: elapsed 6.643ms, delaying 0.551ms
(requested 7.194ms) [preauth]
debug3: mm_request_receive: entering
debug3: monitor_read: checking request 100
debug1: PAM: initializing for "rwk"
debug1: PAM: setting PAM_RHOST to "basement-gentoo.krautclan.com"
debug1: PAM: setting PAM_TTY to "ssh"
debug2: monitor_read: 100 used once, disabling now
debug3: userauth_finish: failure partial=0 next
methods="publickey,password,hostbased" [preauth]
debug3: send packet: type 51 [preauth]
Connection closed by authenticating user rwk 192.168.1.17 port 46500
[preauth]
debug1: do_cleanup [preauth]
debug3: PAM: sshpam_thread_cleanup entering [preauth]
debug1: monitor_read_log: child log fd closed
debug3: mm_request_receive: entering
debug3: monitor_read: checking request 4
debug3: mm_answer_authserv: service=ssh-connection, style=
debug2: monitor_read: 4 used once, disabling now
debug3: mm_request_receive: entering
debug1: do_cleanup
debug1: PAM: cleanup
debug3: PAM: sshpam_thread_cleanup entering
debug1: Killing privsep child 18370

And basement-gentoo just says:

rwk at basement-gentoo /etc/ssh $ ssh -p 1023 -o
PreferredAuthentications=hostbased gemini pwd 
rwk at gemini: Permission denied (publickey,password,hostbased).

NOTE this line in the server debug output above:

debug3: append_hostkey_type: ssh-rsa key not permitted by
HostkeyAlgorithms [preauth]

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