Can't make sshd+pam+ldap to work (AuthorizedKeysCommand?)

Question

What I did:

• Installed libpam-ldapd

• Set up /etc/ldap/ldap.conf

• Set up /etc/ssh/ldap-keys.sh as root:root 0755, confirmed it works (/etc/ssh/ldap_keys.sh amadan returns my public keys from LDAP).

• Set up /etc/nsswitch.conf: passwd, sudo and shadow now say compat ldap, and new line sudoers has ldap.

• Set up /etc/ssh/sshd_config: AuthorizedKeysCommand points to the file above, AuthorizedKeysCommandUser to a newly created dedicated user

• Set up /usr/share/pam-configs/mkhomedir; ran pam-auth-update.

Current situation is that when I try to log in, AuthorizedKeysCommand (/etc/ssh/ldap-keys.sh) is never run. I also do not know whether or not the rest of my configuration is correct or not, but I can't tell yet on account of sshd always reporting "invalid user":

Oct 17 17:22:59 xxx sshd[86244]: Invalid user amadan from yyy
Oct 17 17:22:59 xxx sshd[86244]: input_userauth_request: invalid user amadan [preauth]
Oct 17 17:23:01 xxx sshd[86244]: Connection closed by yyy [preauth]

I know I'm doing something wrong... but what?

EDIT: relevant PAM settings:

# auth
auth    [success=2 default=ignore]  pam_unix.so nullok_secure debug
auth    [success=1 default=ignore]  pam_ldap.so minimum_uid=1000 use_first_pass debug
auth    requisite           pam_deny.so
auth    required            pam_permit.so
auth    optional            pam_cap.so 

# account
account [success=2 new_authtok_reqd=done default=ignore]    pam_unix.so 
account [success=ok new_authtok_reqd=done ignore=ignore user_unknown=ignore authinfo_unavail=ignore default=bad]    pam_ldap.so minimum_uid=1000
account requisite           pam_deny.so
account required            pam_permit.so

EDIT: strace excerpt on this sshd:

open("/lib/x86_64-linux-gnu/security/pam_ldap.so", O_RDONLY|O_CLOEXEC) = 8
read(8, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\20\0\0\0\0\0\0"..., 832) = 832
fstat(8, {st_mode=S_IFREG|0644, st_size=26544, ...}) = 0
mmap(NULL, 2121744, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 8, 0) = 0x7f58df52b000
mprotect(0x7f58df531000, 2093056, PROT_NONE) = 0
mmap(0x7f58df730000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 8, 0x5000) = 0x7f58df730000
close(8)                                = 0
mprotect(0x7f58df730000, 4096, PROT_READ) = 0
open("/lib/x86_64-linux-gnu/security/pam_deny.so", O_RDONLY|O_CLOEXEC) = 8

Strace excerpt from a working sshd (on another server):

open("/lib/x86_64-linux-gnu/security/pam_ldap.so", O_RDONLY|O_CLOEXEC) = 8
read(8, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360\37\0\0\0\0\0\0"..., 832) = 832
fstat(8, {st_mode=S_IFREG|0644, st_size=47792, ...}) = 0
mmap(NULL, 2142888, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 8, 0) = 0x7f8ef8a3c000
mprotect(0x7f8ef8a46000, 2097152, PROT_NONE) = 0
mmap(0x7f8ef8c46000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 8, 0xa000) = 0x
close(8)                                = 0
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 8
fstat(8, {st_mode=S_IFREG|0644, st_size=152262, ...}) = 0
mmap(NULL, 152262, PROT_READ, MAP_PRIVATE, 8, 0) = 0x7f8efcee1000
close(8)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2", O_RDONLY|O_CLOEXEC) = 8

In the working sshd, pam_ldap.so invokes libldap_r-2.4.so.2; in this one, it does not; it exits without doing much, and immediately proceeds to the next PAM module. I do not know why.

Answer 1

It would appear that the cache maintained by the Name Service Caching Daemon has grown stale/was not updated to reflect the new LDAP settings.

sudo /etc/init.d/nscd restart

should restart the service and update the cache.