在LINUX系统上建立FTP加密传输

作者：llzqq
联系：llzqq@126.com
来自：www.chinaunix.net

在众多的FTP服务器中PROFTPD由于它的配置灵活，安装简便。近年来一直受到人们的喜爱。通常情况下FTP包括认证过程，传输是明文传输的，在传输一些敏感数据时总是不能让人放心。今天我在网上找了一些零散的资料结合自己的实作写了个帖子贡献给大家。

下载最新的软件版本：

# wget ftp://ftp.proftpd.org/distrib/source/proftpd-1.3.0rc3.tar.gz

首先创建ROFTPD运行的用户和组：

# groupadd nogroup
# useradd –g nogroup –d /dev/null –s /sbin/nologin nobody

首先创建上传下载的用户和组：

# groupadd ftp
# useradd –g ftp –d /home/down –s /sbin/nologin down
# useradd –g ftp –d /home/upload –s /sbin/nologin upload
用户密码设置略

编译安装PROFRPD:

# tar –zxvf proftpd-1.3.0rc3.tar.gz
# cd proftpd-1.3.0rc3
# ./configure
--prefix=/usr/local/proftpd
--sysconfdir=/etc
--enable-autoshadow
--localstatedir=/var/run
--enable-ctrls
--with-modules=mod_tls

# make
# make install

配置PROFTPD服务器：

# vi /etc/proftpd.conf
================+================+=================
# This is a basic ProFTPD configuration file (rename it to
# ‘proftpd.conf‘ for actual use. It establishes a single server
# and a single anonymous login. It assumes that you have a user/group
# "nobody" and "ftp" for normal operation and anon.
ServerName "llzqq"
ServerType standalone
DefaultServer on
AllowRetrieveRestart on
AllowStoreRestart on
ServerType standalone
ServerIdent on
SystemLog /var/log/proftpd.log
UseReverseDNS off
IdentLookups off
RequireValidShell off
# Port 21 is the standard FTP port.
Port 21
# Umask 022 is a good standard umask to prevent new dirs and files
# from being group and world writable.
Umask 022
MaxInstances 100
# Set the user and group under which the server will run.
User nobody
Group nogroup
# To cause every FTP user to be "jailed" (chrooted) into their home
# directory, uncomment this line.
DefaultRoot ~
# Normally, we want files to be overwriteable.
<Directory />
AllowOverwrite on
</Directory>
# We want ‘welcome.msg‘ displayed at login, and ‘.message‘ displayed
# in each newly chdired directory.
DisplayLogin .welcome
DisplayFirstChdir .message
# Limit User of being enbled login ftp server
<Limit LOGIN>
AllowGroup ftp
DenyAll
</Limit>
#########################ssl/tls############################
# MOD_TLS SETTING
<IfModule mod_tls.c>
TLSEngine on
TLSLog /var/log/proftpd-tls.log
TLSProtocol SSLv23
# Are clients required to use FTP over TLS when talking to this server?
TLSRequired ctrl
# Server‘s certificate
TLSRSACertificateFile /etc/proftpd.crt
TLSRSACertificateKeyFile /etc/proftpd.key
# Authenticate clients that want to use FTP over TLS
TLSVerifyClient off
#########################ssl/tls############################
<Directory /home/down>
<Limit WRITE>
DenyGroup ftp
</Limit>
TransferRate RETR 150 group ftp
</Directory>
<Directory /home/upload>
<Limit RMD RNFR DELE RETR>
DenyGroup ftp
</Limit>
TransferRate STOR 150 group ftp
</Directory>
MaxClientsPerHost 200
PassivePorts 55000 56000
================+================+=================

创建PROFTPD的日志文件：

# touch /var/log/proftpd.log
# touch /var/log/proftpd-tls.log
# chown nobody:nogroup /var/log/proftpd.log /var/log/proftpd-tls.log

创建SSL传输的证书和密匙：

# cp /usr/share/ssl/openssl.cnf ./
# openssl req -new -x509 -nodes -config openssl.cnf -out proftpd.crt –keyout proftpd.key
这里安装提示需要输入证书信息略

把证书和密匙复制到指定目录：
# cp proftpd.crt proftpd.key /etc/

最后创建PROFTPD启动教本：

# vi /etc/init.d/proftpd
================+================+=================
#!/bin/sh
# Startup script for ProFTPD
# chkconfig: 345 85 15
# description: ProFTPD is an enhanced FTP server
# processname: proftpd
# config: /etc/proftpd.conf
# Source function library.
. /etc/rc.d/init.d/functions

if [ -f /etc/sysconfig/proftpd ]; then
. /etc/sysconfig/proftpd
fi
PATH="$PATH:/usr/local/proftpd/sbin"
# See how we were called.
case "$1" in
start)
echo -n "Starting proftpd: "
daemon proftpd $OPTIONS
echo
touch /var/lock/subsys/proftpd
;;
stop)
echo -n "Shutting down proftpd: "
killproc proftpd
echo
rm -f /var/lock/subsys/proftpd
;;
status)
status proftpd
;;
restart)
$0 stop
$0 start
;;
reread)
echo -n "Re-reading proftpd config: "
killproc proftpd -HUP
echo
;;
suspend)
hash ftpshut >/dev/null 2>&1
if [ $? = 0 ]; then
if [ $# -gt 1 ]; then
shift
echo -n "Suspending with ‘$*‘ "
ftpshut $*
else
echo -n "Suspending NOW "
ftpshut now "Maintanance in progress"
fi
else
echo -n "No way to suspend "
fi
echo
;;
resume)
if [ -f /etc/shutmsg ]; then
echo -n "Allowing sessions again "
rm -f /etc/shutmsg
else
echo -n "Was not suspended "
fi
echo
;;
*)
echo -n "Usage: $0 {start|stop|restart|status|reread|resume"
hash ftpshut
if [ $? = 1 ]; then
echo ‘}‘
else
echo ‘|suspend}‘
echo ‘suspend accepts additional arguments which are passed to ftpshut(8)‘
fi
exit 1
esac

if [ $# -gt 1 ]; then
shift
$0 $*
fi
exit 0
================+================+=================

# chomd 755 /etc/init.d/proftpd
# chkconfig –-add proftpd
# chkconfig proftpd on

到这里ftp服务器端安装设置完毕，登陆服务器的客户端我用了完全免费的FileZilla（前两天网上看到说FileZilla支持SSL不错）。FileZilla的设置也比较简单。本服务器支持两种客户端加密连接方式：

1. FTP over ssl (显示加密)方式连接。
2. FTP over tls (显示加密) 方式连接