[root@linux ~]# rpm -qa | grep telnet
telnet-0.17-31.EL4.3
telnet-server-0.17-31.EL4.3
# WO CentOS 4.x w]M󪩥CpGOL distributionA
# ɦWi|Ӥ@ˡiQ yum  apt 觋Ӧw˳I

ȾAX Red Hat tC / Mandriva tCDҰʤ觋
[root@linux ~]# service xinetd restart
Stopping xinetd:                       [  OK  ]
Starting xinetd:                       [  OK  ]

AXUDҰʤ觋
[root@linux ~]# /etc/init.d/xinetd restart
Stopping xinetd:                       [  OK  ]
Starting xinetd:                       [  OK  ]
# YǪèS restart ﶵAoӮɭԴNݭnGstop A start oI

[root@linux ~]# netstat -tlup
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address  Foreign Address   State   PID/Program name
tcp        0      0 *:telnet       *:*               LISTEN  23817/xinetd

Step 1: ק]w
[root@linux ~]# vi /etc/xinetd.d/telnet
service telnet
{
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = yes  <== NOo̰աINL令 yes NOI
}

Step 2: sҰ xinetd o super daemon
[root@linux ~]# /etc/init.d/xinetd restart

[root@linux ~]# vi /etc/xinetd.d/telnet
# This file had been modified by VBird 2002/11/04
# ѼƳ]w
service telnet
{
        disable         = no
        bind            = 192.168.1.2
        only_from       = 192.168.1.0/24
        # Wo满ȴѤI
        instance        = UNLIMITED
        nice            = 0
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/telnetd
        server_args     = -a none
        log_on_failure  += USERID
}

# AӫhOw~쪺]w
service telnet
{
        disable         = no
        bind            = 140.116.142.196
        only_from       = 140.116.0.0/16
        no_access       = 140.116.32.{10,26}
        # WoT]w~Y檺
        instance        = 10   <==̦h\P 10 ӳsu
        umask           = 022
        nice            = 10
        flags           = REUSE
        socket_type     = stream
        wait            = no
        user            = root
        server          = /usr/sbin/telnetd
        server_args     = -a none
        log_on_failure  += USERID
}

[root@linux ~]# mv /etc/securetty /etc/securetty.bak

[root@linux ~]# vi /etc/pam.d/login
#%PAM-1.0
#auth       required     pam_securetty.so  <== NOoˤ@ANLѧYiI
auth       required     pam_stack.so service=system-auth
auth       required     pam_nologin.so
account    required     pam_stack.so service=system-auth
password   required     pam_stack.so service=system-auth
# pam_selinux.so close should be the first session rule
session    required     pam_selinux.so close
session    required     pam_stack.so service=system-auth
session    required     pam_loginuid.so
session    optional     pam_console.so
# pam_selinux.so open should be the last session rule
session    required     pam_selinux.so multiple open

iptables -A INPUT -p tcp -i $INIF  -s 192.168.0.0/24 --dport 23 -j ACCEPT
iptables -A INPUT -p tcp -i $EXTIF -s 61.xxx.xxx.xxx --dport 23 -j ACCEPT
iptables -A INPUT -p tcp -i $EXTIF                   --dport 23 -j DROP

[root@linux ~]# vi /etc/hosts.allow
in.telnetd: 192.168.0.1, 192.168.0.2, 192.168.0.3, 192.168.0.4
in.telnetd: 192.168.0.5

[root@linux ~]# vi /etc/hosts.deny
in.telnetd : ALL : spawn (/bin/echo Security notice from `/bin/hostname`; \
/bin/echo; /usr/sbin/safe_finger @%h ) | \
/bin/mail -s "%d -%h security" root@localhost & \
: twist ( /bin/echo -e "\n\nWARNING connectin not allowed. \n\n\n" )

1. nJDkG
[root@linux ~]# ssh account@hostname
# sڭ̦ۤvW ssh AȡIhTA man ssh I
[root@linux ~]# ssh dmtsai@localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
RSA key fingerprint is f8:ae:67:0e:f0:e0:3e:bb:d9:88:1e:c9:2e:62:22:72.
Are you sure you want to continue connecting (yes/no)? yes
# WܭnIȥJ㪺 "yes" ӤO Y  y ӤwC
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
dmtsai@localhost's password: <== bo̶JKXAP˪Aù|TI
Last login: Fri Jul  1 14:23:27 2005 from localhost.localdomain
[dmtsai@linux ~]$      <== @IwgnJo
[dmtsai@linux ~]$ exit <== J exit N}DoI

2. nJDAbDOkG
[root@linux ~]# ssh dmtsai@localhost date
dmtsai@localhost's password:
Tue Nov 22 11:57:27 CST 2005
[root@linux ~]# 
# ݡI٬O root IuOH dmtsai bݥDWF@ӫOӤwI

[root@linux ~]# sftp dmtsai@localhost
Connecting to localhost...
dmtsai@localhost's password: <== o̽пJKXڡI
sftp> <== o̴NObݱzJ ftp OaFI

1. NƥѥWǨ컷ݥDWh
[root@linux ~]# scp /etc/crontab dmtsai@localhost:/home/dmtsai/
dmtsai@localhost's password: <== o̽пJKXڡI
crontab                  100%  620     0.6KB/s   00:00
# oӨҤlbAڱNؿ /etc/crontab oɮ׶ǰe dmtsai 
# oӨϥΪ̡AӳoӨϥΪ̬Ob "localhost" DWI
# JӬݤ@UA|@ӶǿƪT]XӳI

2. NƥѻݥDU쥻WI
[root@linux ~]# scp dmtsai@localhost:~/.bashrc .
# oӨҤlhObAڭnN localhost W dmtsai oӤHA
# LaؿU .bashrc ƻsڪWI

psftp: no hostname specified; use "open host.name" to connect
psftp>

psftp: no hostname specified; use "open host.name" to connect
psftp> open test.linux.org
login as: dmtsai
Using username "dmtsai".
dmtsai@linux.dmtsai.tw's password:
Remote working directory is /home/dmtsai
psftp> <== o̴NbݱzJ FTP OFI

[root@linux ~]# vi /etc/hosts.allow
sshd: 192.168.0.1, 192.168.0.2, 192.168.0.3, 192.168.0.4, 192.168.0.5: allow

[root@linux ~]# vi /etc/hosts.deny
sshd : ALL : spawn (/bin/echo Security notice from host `/bin/hostname`; \ 
/bin/echo; /usr/sbin/safe_finger @%h ) | \ 
/bin/mail -s "%d -%h security" root@localhost & \ 
: twist ( /bin/echo -e "\n\nWARNING connectin not allowed.". ) 

0. аȥnb X Window AiJ X Window 觋G
[root@client ~]# startx
# 
[root@client ~]# init 5
@
1. b X Window eAҥΤ@ shell AMJG
[root@client ~]# xhost + 192.168.1.100
192.168.1.100 being added to access control list
# ]ڭ诊 Linux D IP  192.168.1.100
[root@client ~]# init 3   <==  X Server

2. brUJG
[root@client ~]# X -query 192.168.1.100
# iJ X Window oI

[root@linux ~]# vi /etc/xinetd.d/rsh
service shell
{
        disable                 = no
        socket_type             = stream
        wait                    = no
        user                    = root
        log_on_success          += USERID
        log_on_failure          += USERID
        server                  = /usr/sbin/in.rshd
}
# SIunN disable 令 no  YiI

[root@linux ~]# /etc/init.d/xinetd restart

[root@linux ~]# netstat -tlnp | grep 514
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State  PID/Program name
tcp        0      0 0.0.0.0:514   0.0.0.0:*       LISTEN 23369/xinetd
# ݨ 514  port X{NFI

[root@linux ~]# vi /etc/hosts
127.0.0.1       localhost       localhost.localdomain
192.168.1.2     rsh.server      rshserver
192.168.1.100   rsh.client      rshclient
# WȦⳡDA] RSH server  IP O 192.168.1.2 աI

[root@linux ~]# vi /etc/hosts.equiv
rsh.client dmtsai
# oɮת榡O [hostname] [username]
# NAn}񪺨ϥΪ̻PYDLngWhYiI

[root@linux ~]# vi ~dmtsai/.rhosts
rsh.client

[root@linux ~]# vi /etc/skel/.rhosts
rsh.client

[root@linux ~]# vi /etc/pam.d/rsh
#%PAM-1.0
# For root login to succeed here with pam_securetty, "rsh" must be
# listed in /etc/securetty.
auth       required     pam_nologin.so
#auth       required    pam_securetty.so
auth       required     pam_env.so
auth       required     pam_rhosts_auth.so
account    required     pam_stack.so service=system-auth
session    required     pam_stack.so service=system-auth

[root@linux ~]# vi /etc/securetty
.....(ٲ).....
rsh

[dmtsai@rshclient ~]$ rsh [-l ݱb] [ݥDW] [ݥDO]
ѼơG
-l   G@ӻA server P client ynۦPϥΪ̱bW١znI
       pGSܡAznw server ϥΪ̱bW~I
ݥDW  GznnJ rsh.server DW١AOoP /etc/hosts I
ݥDOGznbݾWUFOH

dҤ@Gb rsh.server WUF ls -l / oӫOG
[dmtsai@rshclient ~]$ rsh rsh.server 'ls -l /'
.....Xٲ.....
# `NAڬOϥ dmtsai oӤ@먭ϥΪ̡AӥB rshserver rshclient
# ⳡDW@ӦW dmtsai ϥΪ̱b~Iܩ󨺭 ls -l /
# hOb rsh.server DWOIdNdNI

dҡGd\ݥDơAMNLƻsLӡG
[dmtsai@rshclient ~]# rsh rsh.server 'ls -l ~'
drwx------  3 dmtsai dmtsai     4096 Dec 27  2005 Desktop
-rw-r--r--  1 dmtsai dmtsai     3385 May 29 17:52 bashrc
drwx------  3 dmtsai dmtsai     4096 Mar  6  2006 mail
-rw-r--r--  1 dmtsai dmtsai   883888 May 29 17:51 netcdf.tar.gz
drwxr-xr-x  2 dmtsai dmtsai     4096 Jul 26 16:05 test
-rw-rw-r--  1 dmtsai dmtsai    34816 Mar 19  2006 testing.ppt

[dmtsai@rshclient ~]# rcp -r dmtsai@rsh.server:~/mail .
# [W -r OFnƻsؿI_hܡAiHƻsYiI