{"id":216,"date":"2010-04-28T11:06:00","date_gmt":"2010-04-28T11:06:00","guid":{"rendered":"http:\/\/psyphi.net\/blog\/?p=216"},"modified":"2010-04-28T11:06:00","modified_gmt":"2010-04-28T11:06:00","slug":"active-directory-linux-account-integration","status":"publish","type":"post","link":"https:\/\/psyphi.net\/blog\/2010\/04\/active-directory-linux-account-integration\/","title":{"rendered":"Active Directory + Linux account integration"},"content":{"rendered":"

Firstly a note of warning. I’ve done this mostly using CentOS but there’s no reason it shouldn’t work just as well on other distributions. I’ve gleaned a lot of this information by scouring a lot of other resources around the internet, FAQs, newsgroups etc. but as far as I can remember I wasn’t able to find a coherent article which described all of the required pieces of the puzzle.<\/p>\n

Secondly the objective of this article is to have unified accounting across Windows & Linux, or at least as close as possible. We’re going to use Microsoft Active Directory, Kerberos, Samba, Winbind, pam and nsswitch. We’re also going to end up with consistent uids and gids across multiple linux clients.<\/p>\n

\/etc\/samba\/smb.conf<\/strong><\/p>\n

[global]\r\n\tworkgroup = PSYPHI\r\n\trealm = PSYPHI.LOCAL\r\n\tsecurity = ADS\r\n\tallow trusted domains = No\r\n\tuse kerberos keytab = Yes\r\n\tlog level = 3\r\n\tlog file = \/var\/log\/samba\/%m\r\n\tmax log size = 50\r\n\tprintcap name = cups\r\n\tidmap backend = idmap_rid:PSYPHI=600-20000\r\n\tidmap uid = 600-20000\r\n\tidmap gid = 600-20000\r\n\ttemplate shell = \/bin\/bash\r\n\twinbind enum users = Yes\r\n\twinbind enum groups = Yes\r\n\twinbind use default domain = Yes<\/code><\/pre>\n
\/etc\/krb5.conf<\/strong><\/p>\n
[logging]\r\n default = FILE:\/var\/log\/krb5libs.log\r\n kdc = FILE:\/var\/log\/krb5kdc.log\r\n admin_server = FILE:\/var\/log\/kadmind.log\r\n\r\n[libdefaults]\r\n default_realm = PSYPHI.LOCAL\r\n dns_lookup_realm = true\r\n dns_lookup_kdc = true\r\n ticket_lifetime = 24h\r\n forwardable = yes\r\n\r\n[realms]\r\n EXAMPLE.COM = {\r\n  kdc = kerberos.example.com:88\r\n  admin_server = kerberos.example.com:749\r\n  default_domain = example.com\r\n }\r\n\r\n PSYPHI.LOCAL = {\r\n }\r\n\r\n[domain_realm]\r\n .example.com = EXAMPLE.COM\r\n example.com = EXAMPLE.COM\r\n\r\n psyphi.local = PSYPHI.LOCAL\r\n .psyphi.local = PSYPHI.LOCAL\r\n[appdefaults]\r\n pam = {\r\n   debug = false\r\n   ticket_lifetime = 36000\r\n   renew_lifetime = 36000\r\n   forwardable = true\r\n   krb4_convert = false\r\n }<\/code><\/pre>\n
Next we join the machine to the AD domain – it’s necessary to specify a user with the right privileges. It also prompts for a password.<\/p>\n
net ads join -U administrator<\/code><\/pre>\n
We can check things are working so far by trying to create a kerberos ticket using an existing username. Again it prompts us for a password.<\/p>\n
kinit (username)<\/code><\/pre>\n
Then klist<\/code> gives us output something like this:<\/p>\n
Ticket cache: FILE:\/tmp\/krb5cc_0\r\nDefault principal: username@PSYPHI.LOCAL\r\n\r\nValid starting     Expires            Service principal\r\n04\/28\/10 10:57:32  04\/28\/10 20:57:34  krbtgt\/PSYPHI.LOCAL@PSYPHI.LOCAL\r\n\trenew until 04\/29\/10 10:57:32\r\n\r\n\r\nKerberos 4 ticket cache: \/tmp\/tkt0\r\nklist: You have no tickets cached<\/code><\/pre>\n
Cool, so we have a machine joined to the domain and able to use kerberos tickets. Now we can tell our system to use winbind for fetching account information:<\/p>\n
\/etc\/pam.d\/system-auth-ac<\/strong><\/p>\n
auth        required      pam_env.so\r\nauth        sufficient    pam_unix.so nullok try_first_pass\r\nauth        requisite     pam_succeed_if.so uid >= 500 quiet\r\nauth        sufficient    pam_krb5.so use_first_pass\r\nauth        required      pam_deny.so\r\n\r\naccount     required      pam_unix.so broken_shadow\r\naccount     sufficient    pam_localuser.so\r\naccount     sufficient    pam_succeed_if.so uid < 500 quiet\r\naccount     [default=bad success=ok user_unknown=ignore] pam_krb5.so\r\naccount     required      pam_permit.so\r\n\r\npassword    requisite     pam_cracklib.so try_first_pass retry=3\r\npassword    sufficient    pam_unix.so md5 shadow nullok try_first_pass use_authtok\r\npassword    sufficient    pam_krb5.so use_authtok\r\npassword    required      pam_deny.so\r\n\r\nsession     optional      pam_keyinit.so revoke\r\nsession     required      pam_limits.so\r\nsession     [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid\r\nsession     required      \/lib\/security\/pam_mkhomedir.so \r\nsession     required      pam_unix.so\r\nsession     optional      pam_krb5.so<\/code><\/code><\/pre>\n
If we’re on a 64-bit distribution we’ll find that references to \/lib need to be switched for \/lib64, e.g. \/lib64\/security\/pam_mkhomedir.so . This file will also create new home directories for users if they’re not present during first log-in.<\/p>\n
\/etc\/nsswitch.conf<\/strong><\/p>\n
passwd:     files winbind\r\nshadow:     files winbind\r\ngroup:      files winbind\r\n\r\nhosts:      files dns\r\n\r\nbootparams: nisplus [NOTFOUND=return] files\r\n\r\nethers:     files\r\nnetmasks:   files\r\nnetworks:   files\r\nprotocols:  files\r\nrpc:        files\r\nservices:   files\r\n\r\nnetgroup:   nisplus\r\n\r\npublickey:  nisplus\r\n\r\nautomount:  files nisplus\r\naliases:    files nisplus<\/code><\/pre>\n
Now we need to tell a few services to start on boot<\/p>\n
chkconfig smb on\r\nchkconfig winbind on<\/code><\/pre>\n
and start a few services now<\/p>\n
service smb start\r\nservice winbind start<\/code><\/pre>\n
The Winbind+pam configuration can sometimes take a few minutes to settle down – I occasionally find it’s necessary to wait 5 or 10 minutes before accounts are available. YMMV.<\/p>\n
getent passwd<\/code><\/pre>\n
Should now list local accounts (which take precedence) followed by domain accounts. Using ssh to the box as a domain user should make new home directories in \/home\/PSYPHI\/username. If you decide to migrate home directories from \/home make sure you change uid and gid to the new domain values for that user, then remove the old local account.<\/p>\n
There are a handful of limitations of this approach –<\/p>\n
    \n
  1. Though usernames and groupnames map ok, linux uids still don’t map to the windows uids so permissions don’t quite work across smb\/cifs mounts<\/li>\n
  2. The standard linux tools for user & group modification don’t work for domain accounts (adduser\/usermod\/groupadd\/… etc.)<\/li>\n
  3. Winbind seems unstable. On a lot of systems I’ve resorted to cronning a service winbind restart<\/code> every 15 minutes, which seriously sucks<\/li>\n
  4. … and probably others too<\/li>\n<\/ol>\n
    For debugging \/var\/log\/secure<\/code> is very useful, as are the samba logs in \/var\/log\/samba\/<\/code>.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Firstly a note of warning. I’ve done this mostly using CentOS but there’s no reason it shouldn’t work just as well on other distributions. I’ve gleaned a lot of this information by scouring a lot of other resources around the internet, FAQs, newsgroups etc. but as far as I can remember I wasn’t able to … Continue reading “Active Directory + Linux account integration”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[17],"tags":[340,338,337,336,317,335,199,339,334,341,200],"class_list":["post-216","post","type-post","status-publish","format-standard","hentry","category-sysadmin","tag-accounts","tag-activedirectory","tag-ad","tag-authentication","tag-integration","tag-kerberos","tag-linux","tag-nsswitch","tag-samba","tag-winbind","tag-windows"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t