불필요한 서비스 정리

• https://fedoraproject.org/wiki/SysVinit_to_Systemd_Cheatsheet

# SysV 서비스
$ /sbin/chkconfig --list
 
Note: This output shows SysV services only and does not include native
      systemd services. SysV configuration data might be overridden by native
      systemd configuration.
 
      If you want to list systemd services use 'systemctl list-unit-files'.
      To see services enabled on particular target use
      'systemctl list-dependencies [target]'.
 
hostagent_kr    0:off   1:off   2:on    3:on    4:on    5:on    6:off
network         0:off   1:off   2:on    3:on    4:on    5:on    6:off
noms_nsight     0:off   1:off   2:on    3:on    4:on    5:on    6:off
xe-linux-distribution   0:off   1:off   2:on    3:on    4:on    5:on    6:off
 
xinetd based services:
        eklogin:        on
        eklogin.nhn:    on
        klogin:         on
        klogin.nhn:     on
        kshell:         on
        kshell.nhn:     on
  
# systemd 서비스
$ systemctl list-unit-files --type=service
UNIT FILE                                     STATE
abrt-ccpp.service                             masked
abrt-oops.service                             masked
abrt-pstoreoops.service                       disabled
abrt-vmcore.service                           masked
abrt-xorg.service                             masked
abrtd.service                                 masked
arp-ethers.service                            disabled
atd.service                                   enabled
auditd.service                                masked
[email protected]                               enabled
blk-availability.service                      disabled
...
  
$  ls /etc/systemd/system/*.wants/
/etc/systemd/system/basic.target.wants/:
total 0
lrwxrwxrwx. 1 root root 41 Aug 12  2015 microcode.service -> /usr/lib/systemd/system/microcode.service
 
/etc/systemd/system/default.target.wants/:
total 0
lrwxrwxrwx. 1 root root 57 Aug 12  2015 systemd-readahead-collect.service -> /usr/lib/systemd/system/systemd-readahead-collect.service
lrwxrwxrwx. 1 root root 56 Aug 12  2015 systemd-readahead-replay.service -> /usr/lib/systemd/system/systemd-readahead-replay.service
 
/etc/systemd/system/getty.target.wants/:
total 0
lrwxrwxrwx. 1 root root 38 Aug 12  2015 [email protected] -> /usr/lib/systemd/system/[email protected]
...

root 로그인 터미널 (/etc/securetty)

• /etc/securetty 에는 루트 계정으로 로그인이 가능한 터미널이 명시되어있음
• http://man7.org/linux/man-pages/man5/securetty.5.html
• https://mug896.github.io/bash-shell/tty.html
  • tty:  ****teletypewriter - 콘솔/터미널
  • pty: pseudo tty - 가상 TTY, X윈도우에서의 가상 터미널
  • pts: pseudo tty slave - 원격접속했을 때의 가상 터미널

$ tty
/dev/pts/0

SSH 루트 계정 로그인 (/etc/ssh/sshd_config)

• /etc/ssh/sshd_config
  • PermitRootLogin no 로 하면 SSH를 통한 루트 로그인 거부
  • 그 후 sshd 서비스 재시작