In sec_auth.cc, get_server_groups contains this clause:
if (get_logon_server (domain, server, false)
&& !get_user_groups (server, grp_list, user, domain)
&& get_logon_server (domain, server, true))
get_user_groups (server, grp_list, user, domain);The first call to get_logon_server retrieves cached domain information. We try to look up user groups based on this information, and if fail to find this group information (for any reason), we re-query the AD domain, get a new server, and try again. get_logon_server is a thin wrapper around DsGetDcName; get_logon_server's third parameter determines whether we pass the DS_FORCE_REDISCOVERY flag to DsGetDcName. DsGetDcName's documentation suggests that when doing AD operations, we first retrieve cached information (by omitting DS_FORCE_REDISCOVERY), try doing whatever it is that we're going to do, and if we can't reach the domain controller, ask for another DC name, this time with DS_FORCE_REDISCOVERY, and having found a better DC, try the operation again. The problem I'm having is that this rediscover-and-retry step is slowing down my ssh logons by about three seconds. The DCs on my network (for reasons I don't understand) reject anonymous connections to PIPE\SAMR, making NetUserGetGroups fail with ERROR_ACCESS_DENIED. The first call to get_user_groups fails almost instantaneously, but there's a delay of about three seconds querying the second server, the one found when we call get_logon_server (domain, server, true), and this second call also eventually fails with ERROR_ACCESS_DENIED, probably because the failure is a matter of policy, not of connectivity. Would it be possible not to make the second call to NetUserGetGroups if the first fails for a reason that doesn't have anything to do with network connectivity? The purpose of DS_FORCE_REDISCOVERY seems to be to support failover, and it doesn't seem useful to try a different server if we successfully asked the first server and it just happened to say "no". (By the way: how on earth does logon eventually succeed if group enumeration fails? I'm using the stored-password authentication method, and when sshd eventually connects, my user (according to whoami.exe /priv) is a member of the groups I expect.)
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