cntlm 是一个HTTP二级代理软件。 它主要的作用，是在能代理上网的前提下，给这个代理再做一个代理，提供给更多的下级用户。 下级用户不需要、也不可能知道代理的账户密码，这样既保障了安全、又实现了方便。
背景介绍
公司内部提供代理上网，但需要登录。考虑到yum、http_proxy等方式使用时会存在密码泄露风险，故采用 cntlm 做一个二级代理，方便使用。cntlm 具有以下优势：
- 密码密文
- 可以设置黑白名单
- 轻量级、安装配置简单
安装方式：编译安装
下载地址:
配置文件样例
#
# Cntlm Authentication Proxy Configuration
#
# NOTE: all values are parsed literally, do NOT escape spaces,
# do not quote. Use 0600 perms if you use plaintext password.
#
Username xxxx
Domain xxxx
#Password xxxxx
# NOTE: Use plaintext password only at your own risk
# Use hashes instead. You can use a "cntlm -M" and "cntlm -H"
# command sequence to get the right config for your environment.
# See cntlm man page
# Example secure config shown below.
# PassLM 1AD35398BE6565DDB5C4EF70C0593492
# PassNT 77B9081511704EE852F94227CF48A793
### Only for user 'testuser', domain 'corp-uk'
# PassNTLMv2 D5826E9C665C37C80B53397D5C07BBCB
# Specify the netbios hostname cntlm will send to the parent
# proxies. Normally the value is auto-guessed.
#
# Workstation netbios_hostname
# List of parent proxies to use. More proxies can be defined
# one per line in format <proxy_ip>:<proxy_port>
#
#Proxy 10.0.0.41:8080
Proxy proxy.xxx.com:8080
# List addresses you do not want to pass to parent proxies
# * and ? wildcards can be used
#
NoProxy localhost, 127.0.0.*, 10.*, 192.168.*
# Specify the port cntlm will listen on
# You can bind cntlm to specific interface by specifying
# the appropriate IP address also in format <local_ip>:<local_port>
# Cntlm listens on 127.0.0.1:3128 by default
#
Listen 50000
# If you wish to use the SOCKS5 proxy feature as well, uncomment
# the following option. It can be used several times
# to have SOCKS5 on more than one port or on different network
# interfaces (specify explicit source address for that).
#
# WARNING: The service accepts all requests, unless you use
# SOCKS5User and make authentication mandatory. SOCKS5User
# can be used repeatedly for a whole bunch of individual accounts.
#
#SOCKS5Proxy 8010
#SOCKS5User dave:password
# Use -M first to detect the best NTLM settings for your proxy.
# Default is to use the only secure hash, NTLMv2, but it is not
# as available as the older stuff.
#
# This example is the most universal setup known to man, but it
# uses the weakest hash ever. I won't have it's usage on my
# conscience. :) Really, try -M first.
#
Auth NTLM
#Flags 0x06820000
# Enable to allow access from other computers
#
Gateway yes
# Useful in Gateway mode to allow/restrict certain IPs
# Specifiy individual IPs or subnets one rule per line.
#
Allow 127.0.0.1
Allow 192.168.3.0/24
Allow 10.10.4.0/24
Deny 0/0
# GFI WebMonitor-handling plugin parameters, disabled by default
#ISAScannerSize 1024
#ISAScannerAgent Wget/
#ISAScannerAgent APT-HTTP/
#ISAScannerAgent Yum/
# Headers which should be replaced if present in the request
#
#Header User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows 98)
# Tunnels mapping local port to a machine behind the proxy.
# The format is <local_port>:<remote_host>:<remote_port>
#
#Tunnel 11443:remote.com:443
NTLM xxxxxxxxxxxxxxxxxxx
启动方式
cntlm -c /etc/cntlm.conf
检测配置是否正确
cntlm -c /etc/cntlm.conf -v
生成NTLM密码
提取以下内容：
Proxy-Authorization => NTLM TlRMTVNTUAABAAAABbIIogsACwAsAAAADAAMACAAAABZVU5ZSVlVQU4tREJORVVTT0ZULkNPTQ==
cntlm -vc /etc/cntlm.conf -M http://baidu.com
