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  • PAM preventing login?

    Posted on

    Hello all.

    We are unable to ssh to a RHEL 6.6 server in our environment with any account except root.

    Thankfully, root still works fine.

    Below is the verbose ssh output as well as what's written to /var/log/secure when we try to log in with a non-root account.

    I changed account passwords with root and "chage -l" indicates it's been updated and never expires but the problem persists.

    I also included contents of a few PAM files.

    I compared them to other RHEL 6 servers in our environment that are not having this problem and they look the same.

    Not sure where the problem lies.

    Any suggestions would be appreciated.

    Thanks for your time.

    -Tom

    OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017
    debug1: Reading configuration data /home/c01362/.ssh/config
    debug1: /home/c01362/.ssh/config line 10: Applying options for *
    debug1: Reading configuration data /etc/ssh/ssh_config
    debug1: /etc/ssh/ssh_config line 56: Applying options for *
    debug2: resolving "ahlsnqalmob304.almob.ds.sjhs.com" port 22
    debug2: ssh_connect_direct: needpriv 0
    debug1: Connecting to ahlsnqalmob304.almob.ds.sjhs.com [10.60.8.116] port 22.
    debug1: Connection established.
    debug1: identity file /home/c01362/.ssh/id_rsa type 1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_rsa-cert type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_dsa type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_dsa-cert type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_ecdsa type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_ecdsa-cert type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_ed25519 type -1
    debug1: key_load_public: No such file or directory
    debug1: identity file /home/c01362/.ssh/id_ed25519-cert type -1
    debug1: Enabling compatibility mode for protocol 2.0
    debug1: Local version string SSH-2.0-OpenSSH_7.4
    debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
    debug1: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000000
    debug2: fd 3 setting O_NONBLOCK
    debug1: Authenticating to ahlsnqalmob304.almob.ds.sjhs.com:22 as 'c01362'
    debug3: hostkeys_foreach: reading file "/home/c01362/.ssh/known_hosts"
    debug3: record_hostkey: found key type RSA in file /home/c01362/.ssh/known_hosts:549
    debug3: load_hostkeys: loaded 1 keys from ahlsnqalmob304.almob.ds.sjhs.com
    debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa
    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,curve25519-sha256@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-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-

    sha1,diffie-hellman-group1-sha1,ext-info-c
    debug2: host key algorithms: ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-

    v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-

    nistp384,ecdsa-sha2-nistp521,ssh-ed25519,ssh-dss
    debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-

    cbc
    debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-

    cbc
    debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-

    64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
    debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-

    64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
    debug2: compression ctos: none,zlib@openssh.com,zlib
    debug2: compression stoc: none,zlib@openssh.com,zlib
    debug2: languages ctos:
    debug2: languages stoc:
    debug2: first_kex_follows 0
    debug2: reserved 0
    debug2: peer server KEXINIT proposal
    debug2: KEX algorithms: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
    debug2: host key algorithms: ssh-rsa,ssh-dss
    debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-

    cbc,arcfour,rijndael-cbc@lysator.liu.se
    debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-

    cbc,arcfour,rijndael-cbc@lysator.liu.se
    debug2: MACs ctos: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
    debug2: MACs stoc: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
    debug2: compression ctos: none,zlib@openssh.com
    debug2: compression stoc: none,zlib@openssh.com
    debug2: languages ctos:
    debug2: languages stoc:
    debug2: first_kex_follows 0
    debug2: reserved 0
    debug1: kex: algorithm: diffie-hellman-group-exchange-sha256
    debug1: kex: host key algorithm: ssh-rsa
    debug1: kex: server->client cipher: aes128-ctr MAC: umac-64@openssh.com compression: none
    debug1: kex: client->server cipher: aes128-ctr MAC: umac-64@openssh.com compression: none
    debug1: kex: diffie-hellman-group-exchange-sha256 need=16 dh_need=16
    debug1: kex: diffie-hellman-group-exchange-sha256 need=16 dh_need=16
    debug3: send packet: type 34
    debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(102430728192) sent
    debug3: receive packet: type 31
    debug1: got SSH2_MSG_KEX_DH_GEX_GROUP
    debug2: bits set: 1547/3072
    debug3: send packet: type 32
    debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
    debug3: receive packet: type 33
    debug1: got SSH2_MSG_KEX_DH_GEX_REPLY
    debug1: Server host key: ssh-rsa SHA256:kuRZVN43wP1Q0+lQe11MWcBt/u9p2H6gOtNZP8xkG1A
    debug3: hostkeys_foreach: reading file "/home/c01362/.ssh/known_hosts"
    debug3: record_hostkey: found key type RSA in file /home/c01362/.ssh/known_hosts:549
    debug3: load_hostkeys: loaded 1 keys from ahlsnqalmob304.almob.ds.sjhs.com
    debug1: Host 'ahlsnqalmob304.almob.ds.sjhs.com' is known and matches the RSA host key.
    debug1: Found key in /home/c01362/.ssh/known_hosts:549
    debug2: bits set: 1515/3072
    debug3: send packet: type 21
    debug2: set_newkeys: mode 1
    debug1: rekey after 4294967296 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 after 4294967296 blocks
    debug2: key: /home/c01362/.ssh/id_rsa (0x55d8540c7480)
    debug2: key: /home/c01362/.ssh/id_dsa ((nil))
    debug2: key: /home/c01362/.ssh/id_ecdsa ((nil))
    debug2: key: /home/c01362/.ssh/id_ed25519 ((nil))
    debug3: send packet: type 5
    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,gssapi-keyex,gssapi-with-mic,password
    debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,password
    debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
    debug3: authmethod_lookup gssapi-keyex
    debug3: remaining preferred: gssapi-with-mic,publickey,keyboard-interactive,password
    debug3: authmethod_is_enabled gssapi-keyex
    debug1: Next authentication method: gssapi-keyex
    debug1: No valid Key exchange context
    debug2: we did not send a packet, disable method
    debug3: authmethod_lookup gssapi-with-mic
    debug3: remaining preferred: publickey,keyboard-interactive,password
    debug3: authmethod_is_enabled gssapi-with-mic
    debug1: Next authentication method: gssapi-with-mic
    debug1: Unspecified GSS failure. Minor code may provide more information
    No Kerberos credentials available (default cache: FILE:/tmp/krb5cc_103085)

    debug1: Unspecified GSS failure. Minor code may provide more information
    No Kerberos credentials available (default cache: FILE:/tmp/krb5cc_103085)

    debug2: we did not send a packet, disable method
    debug3: authmethod_lookup publickey
    debug3: remaining preferred: keyboard-interactive,password
    debug3: authmethod_is_enabled publickey
    debug1: Next authentication method: publickey
    debug1: Offering RSA public key: /home/c01362/.ssh/id_rsa
    debug3: send_pubkey_test
    debug3: send packet: type 50
    debug2: we sent a publickey packet, wait for reply
    debug3: receive packet: type 60
    debug1: Server accepts key: pkalg ssh-rsa blen 279
    debug2: input_userauth_pk_ok: fp SHA256:PjaIknqBmBoRT8kFWw0wzsEpk4qohK+DryxKLNB7ApA
    debug3: sign_and_send_pubkey: RSA SHA256:PjaIknqBmBoRT8kFWw0wzsEpk4qohK+DryxKLNB7ApA
    debug3: send packet: type 50
    debug3: receive packet: type 53
    debug3: input_userauth_banner
    You are required to change your password immediately (root enforced)
    Authentication failed.

    Written to /var/log/secure during ssh attempt to this server:
    Feb 22 15:41:19 sshd[5950]: pam_unix(sshd:account): expired password for user (root enforced)
    Feb 22 15:41:19 sshd[5951]: fatal: Access denied for user by PAM account configuration
    Feb 22 15:58:11 passwd: pam_unix(passwd:chauthtok): password changed for user
    Feb 22 15:58:11 passwd: gkr-pam: couldn't update the 'login' keyring password: no old password was entered
    Feb 22 15:58:29 sshd[6458]: fatal: Access denied for user by PAM account configuration

    cat /etc/pam.d/sshd

    %PAM-1.0

    auth required pam_sepermit.so
    auth include password-auth
    account required pam_nologin.so
    account include password-auth
    password include password-auth

    pam_selinux.so close should be the first session rule

    session required pam_selinux.so close
    session required pam_loginuid.so

    pam_selinux.so open should only be followed by sessions to be executed in the user context

    session required pam_selinux.so open env_params
    session optional pam_keyinit.so force revoke
    session include password-auth

    cat /etc/pam.d/password-auth

    %PAM-1.0

    This file is auto-generated.

    User changes will be destroyed the next time authconfig is run.

    auth required pam_env.so
    auth sufficient pam_unix.so nullok try_first_pass
    auth requisite pam_succeed_if.so uid >= 500 quiet
    auth required pam_deny.so

    account required pam_unix.so
    account sufficient pam_localuser.so
    account sufficient pam_succeed_if.so uid 500 quiet
    account required pam_permit.so

    password requisite pam_cracklib.so try_first_pass retry=3 type=
    password sufficient pam_unix.so sha512 shadow nullok try_first_pass use_authtok
    password required pam_deny.so

    session optional pam_keyinit.so revoke
    session required pam_limits.so
    session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
    session required pam_unix.so

    cat /etc/pam.d/system-auth

    %PAM-1.0

    This file is auto-generated.

    User changes will be destroyed the next time authconfig is run.

    auth required pam_env.so
    auth sufficient pam_fprintd.so
    auth sufficient pam_unix.so nullok try_first_pass
    auth requisite pam_succeed_if.so uid >= 500 quiet
    auth required pam_deny.so

    account required pam_unix.so
    account sufficient pam_localuser.so
    account sufficient pam_succeed_if.so uid 500 quiet
    account required pam_permit.so

    password requisite pam_cracklib.so try_first_pass retry=3 type=
    password sufficient pam_unix.so sha512 shadow nullok try_first_pass use_authtok
    password required pam_deny.so

    session optional pam_keyinit.so revoke
    session required pam_limits.so
    session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
    session required pam_unix.so

    chage -l output for the account:
    Last password change : Feb 22, 2020
    Password expires : never
    Password inactive : never
    Account expires : never
    Minimum number of days between password change : 0
    Maximum number of days between password change : 99999
    Number of days of warning before password expires : 7

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