I'm trying to configure sudo in such a way that I don't have to enter my password when I connect from a specific IP range. I tried to this with the following line in my /etc/sudoers file:
%wheel 10.1.2.0/24 = (ALL) NOPASSWD: ALL visudo doesn't give an error when I close it, so the syntax is valid. But when I log in from an server in the 10.1.2.0/24 ip range with a user which is in the wheel group, I still need to supply the password of the account:
[cybertinus@server ~]$ id uid=500(cybertinus) gid=500(cybertinus) groups=500(cybertinus),10(wheel),48(apache) [cybertinus@server ~]$ who cybertinus pts/0 2015-09-30 09:57 (10.1.2.3) cybertinus pts/1 2015-09-30 13:03 (10.1.2.3) [cybertinus@server ~]$ sudo -i [sudo] password for cybertinus: What I did notice however is that the following line is added to my /var/log/secure when I enter an incorrect password at this prompt:
Sep 30 13:04:31 server sudo: pam_unix(sudo-i:auth): authentication failure; logname=cybertinus uid=500 euid=0 tty=/dev/pts/1 ruser=cybertinus rhost= user=cybertinus rhost= is empty. So my theory is that sudo doesn't get the remote host passed on from the ssh session. Is there a way to let sudo know from which host this interactive ssh session is running?
I do know that this is a security risk. But the IP range in question is the IP range I use on my VPN network. In other words: it is not connected to the internet directly. If an hacker gets onto my VPN network, I have another problem ;).
In order for you to get the complete picture, this is my entier /etc/sudoers file:
## Sudoers allows particular users to run various commands as ## the root user, without needing the root password. ## ## Examples are provided at the bottom of the file for collections ## of related commands, which can then be delegated out to particular ## users or groups. ## ## This file must be edited with the 'visudo' command. ## Host Aliases ## Groups of machines. You may prefer to use hostnames (perhaps using ## wildcards for entire domains) or IP addresses instead. # Host_Alias FILESERVERS = fs1, fs2 # Host_Alias MAILSERVERS = smtp, smtp2 ## User Aliases ## These aren't often necessary, as you can use regular groups ## (ie, from files, LDAP, NIS, etc) in this file - just use %groupname ## rather than USERALIAS # User_Alias ADMINS = jsmith, mikem ## Command Aliases ## These are groups of related commands... ## Networking # Cmnd_Alias NETWORKING = /sbin/route, /sbin/ifconfig, /bin/ping, /sbin/dhclient, /usr/bin/net, /sbin/iptables, /usr/bin/rfcomm, /usr/bin/wvdial, /sbin/iwconfig, /sbin/mii-tool ## Installation and management of software # Cmnd_Alias SOFTWARE = /bin/rpm, /usr/bin/up2date, /usr/bin/yum ## Services # Cmnd_Alias SERVICES = /sbin/service, /sbin/chkconfig ## Updating the locate database # Cmnd_Alias LOCATE = /usr/bin/updatedb ## Storage # Cmnd_Alias STORAGE = /sbin/fdisk, /sbin/sfdisk, /sbin/parted, /sbin/partprobe, /bin/mount, /bin/umount ## Delegating permissions # Cmnd_Alias DELEGATING = /usr/sbin/visudo, /bin/chown, /bin/chmod, /bin/chgrp ## Processes # Cmnd_Alias PROCESSES = /bin/nice, /bin/kill, /usr/bin/kill, /usr/bin/killall ## Drivers # Cmnd_Alias DRIVERS = /sbin/modprobe # Defaults specification # # Disable "ssh hostname sudo <cmd>", because it will show the password in clear. # You have to run "ssh -t hostname sudo <cmd>". # #Defaults requiretty # # Refuse to run if unable to disable echo on the tty. This setting should also be # changed in order to be able to use sudo without a tty. See requiretty above. # Defaults !visiblepw # # Preserving HOME has security implications since many programs # use it when searching for configuration files. Note that HOME # is already set when the the env_reset option is enabled, so # this option is only effective for configurations where either # env_reset is disabled or HOME is present in the env_keep list. # Defaults always_set_home Defaults env_reset Defaults env_keep = "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS_COLORS" Defaults env_keep += "MAIL PS1 PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE" Defaults env_keep += "LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES" Defaults env_keep += "LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE" Defaults env_keep += "LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY" # # Adding HOME to env_keep may enable a user to run unrestricted # commands via sudo. # # Defaults env_keep += "HOME" Defaults secure_path = /sbin:/bin:/usr/sbin:/usr/bin ## Next comes the main part: which users can run what software on ## which machines (the sudoers file can be shared between multiple ## systems). ## Syntax: ## ## user MACHINE=COMMANDS ## ## The COMMANDS section may have other options added to it. ## ## Allow root to run any commands anywhere root ALL=(ALL) ALL ## Allows members of the 'sys' group to run networking, software, ## service management apps and more. # %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE, DRIVERS ## Allows people in group wheel to run all commands %wheel 10.1.2.3=(ALL) NOPASSWD: ALL %wheel ALL=(ALL) ALL ## Same thing without a password # %wheel ALL=(ALL) NOPASSWD: ALL ## Allows members of the users group to mount and unmount the ## cdrom as root # %users ALL=/sbin/mount /mnt/cdrom, /sbin/umount /mnt/cdrom ## Allows members of the users group to shutdown this system # %users localhost=/sbin/shutdown -h now ## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment) #includedir /etc/sudoers.d You see a reference to /etc/sudoers.d at the end. This is the contents of that directory:
[root@server ~]# ls /etc/sudoers.d | wc -l 0 In other words: In /etc/sudoers.d is nothing that could overrule the normal /etc/sudoers file.
