NIS
Network Information Service (NIS) is a protocol developed by Sun to allow one to defer user authentication to a server. The server software is in the ypservAUR package, and the client software is in the yp-toolsAUR package. ypbind-mtAUR is also available, which is a multi threaded version of the client daemon.
Contents
NIS Server
Install Packages
Install the ypbind-mtAUR, ypservAUR, and yp-toolsAUR packages.
Configuration
/etc/hosts
Add your server's external (not 127.0.0.1) IP address to the hosts file. Make sure it is the first non-commented line in the file, yes, even above the localhost line, like so:
# # /etc/hosts: static lookup table for host names # #<ip-address> <hostname.domain.org> <hostname> #::1 localhost.localdomain localhost 192.168.1.10 nis_server.domain.com nis_server 127.0.0.1 localhost.localdomain localhost nis_server # End of file
This is due to a peculiarity in ypinit (maybe it's a bug, maybe it's a feature), which will always add the first line in /etc/hosts to the list of ypservers.
/etc/nisdomainname
Add the domain name to /etc/nisdomainname:
# NISDOMAINNAME="nis-domain-name"
/etc/ypserv.conf
Add rules to /etc/ypserv.conf for your your nis clients of this form:
# ip-address-of-client : nis-domain-name : rule : security
For example:
# 192.168. : home-domain : * : port
For more information see man ypserv.conf.
/var/yp/Makefile
Add or remove files you would like NIS to use to /var/yp/Makefile under the "all" rule.
Default:
# all: passwd group hosts rpc services netid protocols netgrp \ # shadow # publickey networks ethers bootparams printcap mail \ # # amd.home auto.master auto.home auto.local passwd.adjunct \ # # timezone locale netmasks
After that you have to build your NIS database:
# cd /var/yp # make
Or you can do it in a more automated fashion:
# /usr/lib/yp/ypinit -m
If you use this way you may skip manually adding lines to /var/yp/ypservers.
/var/yp/securenets
Add rules to /var/yp/securenets to restrict access:
# 255.255.0.0 192.168.0.0 # Gives access to anyone in 192.168.0.0/16
Be sure to comment out this line, as it gives access to anyone.
# 0.0.0.0 0.0.0.0
/var/yp/ypservers
Add your server to /var/yp/ypservers:
# your.nis.server
Set your domain name
# ypdomainname EXAMPLE.COM
Now edit the /etc/yp.conf file and add your ypserver or nis server.
ypserver nis_server
Start NIS Daemons
Start/enable the following systemd units:
rpcbind.serviceypbind.serviceypserv.service-
yppasswdd.service(to allow clients to change their password withpasswd)
NIS Client
Install Packages
The first step is to install the tools that you need. This provides the configuration files and general tools needed to use NIS.
# pacman -S yp-tools ypbind-mt
Configuration
Set your domain name
# ypdomainname EXAMPLE.COM
You can apply this permanently by editing /etc/nisdomainname and adding:
# NISDOMAINNAME="EXAMPLE.COM"
Now edit the /etc/yp.conf file and add your ypserver or nis server.
ypserver nis_server
/etc/hosts
It may be a good idea to add your NIS server to /etc/hosts
192.168.1.10 nis_server.domain.com nis_server
Start NIS Daemons
Start/enable the rpcbind.service and ypbind.service systemd units.
Early testing
To test the setup so far you can run the command yptest:
# yptest
If it works you will, among other things, see the contents of the NIS user database (which is printed in the same format as /etc/passwd).
/etc/nsswitch.conf
To actually use NIS to log in you have to edit /etc/nsswitch.conf. Modify the lines for passwd, group and shadow to read:
passwd: files nis group: files nis shadow: files nis
And then do not forget
# systemctl restart ypbind
/etc/pam.d/passwd
To allow a user on a client machine to change their password on the server, be sure that yppasswdd.service is started/enabled on the server.
Edit /etc/pam.d/passwd on the client to add the nis parameter to password/pam_unix.so:
password required pam_unix.so sha512 shadow nullok nis
See section 7 of The Linux NIS HOWTO for further information on configuring NIS clients.
Attention on Systemd V235 since 10/2017 (and V239 since 06/2018)
Due a problem with sandboxing on systemd-logind, any IP connections from and to the systemd-logind service are now denied. This will cause failures to log in, even though yptest works as expected, and can also cause accounts-daemon to crash outright. The basic problem is that the default /usr/lib/systemd/system/systemd-logind.service file that ships with systemd specifies IPAddressDeny=any, and this prevents it from communicating with the NIS server at login. Moreover, since V239, that file also specifies RestrictAddressFamilies=AF_UNIX AF_NETLINK, dropping AF_INET AF_INET6 from the list.
There are a few possible solutions:
- Whitelist the address or address range of your NIS server:
This can be done by creating a new .conf file within the /etc/systemd/system/systemd-logind.service.d/, with these lines (the following allows connections from 10.0.*.*, edit as appropriate):
/etc/systemd/system/systemd-logind.service.d/open_network_interface.conf
[Service] RestrictAddressFamilies=AF_UNIX AF_NETLINK AF_INET AF_INET6 IPAddressAllow=10.0.0.0/16
This survives a reboot and updates of the systemd toolchain. It also avoid having to open your system to any IP address.
IPAddressAllow=any, this is does not override the default IPAddressDeny=any set in the main unit file.- Override the system's default
systemd-logind.servicewith a modified local version:
# cp -a /usr/lib/systemd/system/systemd-logind.service /etc/systemd/system # nano /etc/systemd/system/systemd-logind.service
and comment out the line IPAddressDeny=any to read # IPAddressDeny=any. As of V239, you will also need to add AF_INET AF_INET6 to the RestrictAddressFamilies=AF_UNIX AF_NETLINK line.
This solution survives an update of the systemd toolchain and keeps working after a reboot. It does however override all settings in the unit file supplied with systemd, which may cause issues down the track if other unrelated settings are changed upstream. It also opens up access to any IP address, which is not recommended.
- Modify the system's default
systemd-logind.servicedirectly:
Works, but not a recommended solution since it will not survive an update of the systemd toolchain:
# nano /usr/lib/systemd/system/systemd-logind.service
and comment out the line IPAddressDeny=any to read # IPAddressDeny=any. As of V239, you will also need to add AF_INET AF_INET6 to the RestrictAddressFamilies=AF_UNIX AF_NETLINK line.
Note that this also opens up access to any IP address, which is not recommended.
More resources
- The Linux NIS HOWTO,very helpful and generally applicable to Arch Linux.
- YoLinux NIS tutorial
- Quick HOWTO, Configuring NIS