trashVPN各种协议的区别

2021年1月21日发(作者：mill)
Manipulator i
s now used a
s a industria
l robots in
use
, the
control obje
ctives often
appear often i
n industrial automati
on.
In
dustrial
automati
on technology
has gradually mature
d, as mat
ure a technology li
ne ha
s be
en ra
pid
development i
n industrial
automation as
a separate subject. Ma
nipulator appli
cation bega
n to filter int
o welding, l
ogistics, mechani
cal
processi
ng, a
nd ot
her i
ndustries. E
spe
cially at
high
or very low tem
peratures, full of poisonous gases,
high radiati
on
case, robot in
similar cir
cum
stances
showed great
use a
lso
bring
s great conveni
ence to the staff. Precisely
be
cause of this robot to get people's attenti
on
began t
o be a
high
degree
of devel
opment. La
bor rates,
working
conditi
ons, labor inte
nsive a
spe
cts of
promoti
ng devel
opme
nt. Both at
home a
nd a
broa
d to develop the
PLC (programmable l
ogic
controller) is i
n various special cir
cumstances a
nd
under spe
cial
conditions
set for mechani
cal devi
ces. Now tur
ned
on the devel
opme
nt of the mi
croele
ctronics automati
c control
technology a
nd t
he rapi
d devel
opme
nt of the trains, the success of PLC har
dware software and
simulation control
win
big and succe
ssful development, now
conti
nue
s to develop as a factory a
utomation standards. Beca
use robots are g
ood devel
opme
nt of the technology makes a g
ood optimizati
on of productive ca
pital, and robot shows t
his
uni
que a
dvantages,
such as: has g
ood com
patibi
lity, wi
de availa
bility,
hardwar
e is complete, a
nd
programming that can be mastered in
a short time, so i
n the
context of industrial PLC applications be
came ubiquitous. Ma
nipulator i
n many devel
ope
d country agriculture a
nd i
ndustry has
bee
n applied,
such as t
he use of mechani
cal harve
sting large areas
of farmland, repeated operations
on the
high
-speed l
ine that use
s a robotic arm, a
nd so on. Toda
y, the
high level
of automation combi
ned wit
h restricti
ons
on t
he mani
pulator
devel
opment level i
s slightly low
er tha
n the inter
national. T
he de
sign is mai
nly arm weldi
ng machine
by PLC Aut
omation
control. T
his
of design let
desig
ners on in
school
by learn
of has a must of consolidati
on,
understand has
some usually
didn't opport
unitie
s awarene
ss i
n worl
d range within some leadi
ng level of knowle
dge has
has must awarene
ss, hope desig
ners
can i
n yihou of design i
n the
can success of usi
ng in this de
sign i
n the pr
ocee
ds
of experience 1.2 manipulator i
n bot
h at home and
abroa
d of resear
ch pr
ofile aut
omation me
cha
nical arm rese
arch
began Yu 20th
cent
ury medium
-term, after years with with
com
puter and aut
omation te
chnol
ogy of devel
opme
nt, Makes me
cha
nical arm on the
Grand
stage of ind
ustrial aut
omation a
nd shine, gradually be
came an i
ndustrial evaluati
on sta
ndar
ds, a
nd its im
portance can be see
n. Now origi
nal roboti
c arm spe
nt most of mass
producti
on a
nd
use
on the production line,
whi
ch is
programmed roboti
c arm. As the first generation
of manipulator position control
systems main features, althoug
h not back
several generati
ons t
hat ca
n dete
ct the external e
nvironment, but ca
n still
successf
ully com
plete like wel
ding,
painti
ng, del
ivery as well as for materials
simple moveme
nts. Se
cond generation me
cha
nical arms are
equipped wit
h sensors a
nd ma
nipulators hav
e the envir
onme
nt there is a
certain amount
of
hen the mechani
cal arm is to use the
program as a ba
sis. Difference is that t
he robot bega
nd
VPN

（虚拟专用网）
发展至今已经不在是一个单纯 的经过加密的访问隧道了，
它
已经融合了访问控制、传输管理、加密、
路由
选 择、可用性管理等多种功能，并
在全球的

信息
安全
体系中发挥着重 要的作用。也在网络上，有关各种
VPN
协议
优缺点的比较是仁者见仁，
智者 见智，
很多技术人员由于出于使用目的考虑，
包
括访问控制、

安全
和用户简单易用，灵活扩展等各方面，权衡利弊，难以取舍；
尤其在
VOIP
语音环境中，网络安全显得尤为重要，因此现在越来越多的网络电
话和语音网关支

持
VPN
协议
。



PPTP


点对点隧道
协议
(PPTP)
是由包括微软和3Com
等公司组成的
PPTP
论坛开发
的一种点对点隧道协，基于拨号 使用的
PPP
协议使用
PAP
或
CHAP
之类的加密算法，或者使用
Microsoft
的点对点加密算法
MPPE
。其通过跨越基于
TCP/IP
的
数据网络创建
VPN
实现了从远程客户端到专用企业< br>服务器
之间数据的安全传
输。
PPTP
支持通过公共网络（例如
Internet
）建立按需的、多协议的、虚拟专
用网络。
PPTP
允许加密
IP
通讯，然后在要跨越公司
IP
网络或公共
IP
网络
（如
Internet
）发送的
IP
头中对其进行封装。



L2TP
第
2
层隧道协议
(L2TP)
是
IETF
基于
L2F
（
Cisco
的第二层转 发协
议）开发的
PPTP
的后续版本。是一种工业标准
Internet
隧道协议，其可以为
跨越面向数据包的媒体发送点到点协议
(PPP)
框 架提供封装。
PPTP
和
L2TP
都
使用
PPP
协 议对数据进行封装，然后添加附加包头用于数据在
互联网
络上的传
输。
PPT P
只能在两端点间建立单一隧道。
L2TP
支持在两端点间使用多隧道，
用
户可以针对不同的服务质量创建不同的隧道。
L2TP
可以提供隧道验证，而
PPTP
则不支持隧道验证。但是当
L2TP
或
PPTP
与
IPSEC
共同使用时，可以由
IPSEC
提供隧道验证，
不需要在第2
层协议上验证隧道使用
L2TP
。
PPTP
要求
互 联网
络
为
IP
网络。
L2TP
只要求隧道媒介提供面向数据 包的点对点的连接，
L2TP
可以在
IP
（使用
UDP
）< br>，
桢中继永久虚拟电路

（
PVCs),X.25
虚拟电路< br>（
VCs
）
或
ATM
VCs
网络上使用。



IPSec
隧道模式隧道是封装、路由与解封装的整个
过程。隧道将原始数据
包隐藏
（或封装）
在新的数据包内部。
该新的数据 包可能会有新的寻址与路由信
息，从而使其能够通

过网络传输。隧道与数据保密性结 合使用时，在网络上窃
听通讯的人将无法获取原始数据包数据
（以及原始的源和目标）
。
封装的数据包
到达目的地后，会删除封

装，原始数据包头用于将数据包路由到最终目的地。



隧道本身 是封装数据经过的逻辑数据路径，
对原始的源和目的端，
隧道是不
可见的，
而 只能看到网络路径中的点对点连接。
连接双方并不关心隧道起点和终
点之间的任何路由器、交换
机、
代理
服务器
或其他安全网关。
将隧道和数据保密
性结合使用时，可用于提供
VPN
。



封装的数据包在网络中的隧道内部传输。
在此示例中，
该网络是
Internet
。
网关可以是外部
Internet
与专用网络间的周 界网关。周界网关可以是路由器、
防火墙
、
代理服务器或其他安全网关。
另外 ，
在专用网络内部可使用两个网关来
保护网络中不信任的通讯。

m
anipulat
or control m
ode a
nd
programmabl
e controller
s introduction 2.1 S
elect
discussion with ma
nipulator
contr
ol 2.1.1 cl
assificati
on
of control relays
and discrete ele
ctronic
circuit
can
control
old i
ndustrial e
qui
pment,
but also more
common. Ma
inly these tw
o relatively chea
p and you
ca
n meet the ol
d-fashioned,
simple (or
simple) i
ndustrial equipme
nt. So
he
can
see them now,
however t
hese tw
o contr
ol mode
s (relay and discrete ele
ctronic
circuits) are these fatal flaws: (1) cannot a
dapt to t
he complex l
ogic
control, (2) only for the
current
project, t
he lack
of com
patibi
lity and (3) not reforming the sy
stem with e
qui
pment impr
ovements. S
pring for t
he development of
China's modern i
ndustrial a
utomation technology the substa
ntial increase i
n the
level of industrial aut
omation, com
pleted t
he perfect relay of the
com
puter too much.
In terms
of controlling t
he
computer showed
his tw
o great advantage
s: (1) each of the
har
dw
are ca
n be
installe
d on one
or more micr
oprocessors; (2) the
official desig
ner of the
software writing
content control is all a
bout. Now in several ways in t
he context of industrial a
utomation ca
n often
be se
en i
n three ways: (1) Programmable Logica
l Controller (referred to as
IPC); (2) Distri
bute
d Control System (DCS for short), and (3) the Programmable
Logi
cal Controller (PLC for short). 2.1.2 PLC a
nd t
he IPC and DCS
contrast contrast 1, ea
ch of the three technologi
es of origi
ns a
nd
development requirem
ent
s for fast data processing makes it inve
nted the com
puter. The me
n brought i
n terms of hardware there,
usi
ng a hig
h level
of standardi
zation, ca
n use m
ore compatibility tool
s, is a ri
ch software resources, especially t
he ne
ed for immedia
cy in
operational systems. So the com
puter can effectively control i
s used to
control and meet its spee
d, on the virtua
l model
, real-time a
nd i
n computational re
quireme
nts. Distri
bute
d system started wit
h a contr
ol system for industrial a
utomatic i
nstrume
nt use
d to
contr
ol, whereas now it is
successfully deve
loped int
o
industrial control
computer use
d as a
central colle
ction a
nd
distri
bution system and transiti
on
of distributed
contr
ol system in a
nalog
ue ha
ndli
ng, l
oop control,
has beg
un t
o reflect the use of a huge adva
ntage. Thoug
h distri
bute
d system has great adva
ntages in l
oop regulati
on,
but only as a means of conti
nuous
process
contr
ol. Optimization of PLC is the
corre
sponding relay nee
ds wa
s bor
n, its main
use i
n the w
ork order control, early
primary is repla
ced relay this hulking system, focused on the switch
controlli
ng the runni
ng order of functi
ons. Marked
by the micr
oprocessor i
n the early 1970 of the 20th
cent
ury emerged, micr
o-el
ectronics technol
ogy ha
s devel
ope
d rapi
dly,
people soon microel
ectronics processing technology w
ill be
used i
n the
Programm
able
Logi
cal Controller (that is
Manipulator i
s now used a
s a industria
l robots in
use
, the
control obje
ctives often
appear often i
n industrial automati
on.
Industrial
automati
on technology
has gradually mature
d, as mat
ure a technology li
ne ha
s be
en ra
pid
development i
n industrial
automat
ion as
a separate subject. Ma
nipulator appli
cation bega
n to filter int
o welding, l
ogistics, mechani
cal
processi
ng, a
nd ot
her i
ndustries. E
spe
cially at
high
or very low tem
peratures, full of poisonous gases,
high radiati
on
case, robot in
similar cir
cumstances
showed great
use a
lso
bring
s great conveni
ence to the staff. Precisely
be
cause of this robot to get people's attenti
on
began t
o be a
high
degree
of devel
opment. La
bor rates,
working
conditi
ons, labor inte
nsive a
spe
cts of
promoti
ng devel
opme
nt. Both at
home a
nd a
broa
d to develop the
PLC (programmable l
ogic
controller) is i
n various special cir
cumstances a
nd
under spe
cial
conditions
set for mechani
cal devi
ces. Now tur
ned
on the devel
opme
nt of the mi
croele
ctronics automati
c control
technology a
nd t
he rapi
d devel
opme
nt of the trains, the success of PLC har
dware software and
simulation control
win
big and succe
ssful development, now
conti
nue
s to develop as a factory a
utomation standards. Beca
use robots are g
ood devel
opme
nt of the technology makes a g
ood optimizati
on of productive ca
pital, and robot shows t
his
uni
que a
dvantages,
such as: has g
ood com
patibi
lity, wi
de availa
bility,
hardwar
e is complete, a
nd
programming that can be mastered in
a short time, so i
n the
context of industrial PLC applications be
came ubiquitous. Ma
nipulator i
n many devel
ope
d country agriculture a
nd i
ndustry has
bee
n applied,
such as t
he use of mechani
cal harve
sting large areas
of farmland, repeated operations
on the
high
-speed l
ine that use
s a robotic arm, a
nd so on. Toda
y, the
high level
of automation combi
ned wit
h restricti
ons
on t
he mani
pulator
devel
opment level i
s slightly low
er tha
n the inter
national. T
he de
sig
n is mai
nly arm weldi
ng machine
by PLC Aut
omation
control. T
his
of design let
desig
ners on in
school
by learn
of has a must of cons
olidati
on,
understand has
some usually
didn't opport
unitie
s awarene
ss i
n worl
d range within some leadi
ng level of knowle
dge has
has must awarene
ss, hope desig
ners
can i
n yihou of design i
n the
can success of usi
ng in this de
sign i
n the pr
ocee
ds
of ex
perience 1.2 manipulator i
n bot
h at home and
abroa
d of resear
ch pr
ofile aut
omation me
cha
nical arm rese
arch
began Yu 20th
cent
ury medium
-term, after years with with
com
puter and aut
omation te
chnol
ogy of devel
opme
nt, Makes me
cha
nical arm on the
Grand
stage of ind
ustrial aut
omation a
nd shine, gradually be
came an i
ndustrial evaluati
on sta
ndar
ds, a
nd its im
portance can be see
n. Now origi
nal roboti
c arm spe
nt most of mass
producti
on a
nd
use
on the production line,
whi
ch is
programmed roboti
c arm. As the first gen
eration
of manipulator position control
systems main features, althoug
h not back
several generati
ons t
hat ca
n dete
ct the external e
nvironment, but ca
n still
successf
ully com
plete like wel
ding,
painti
ng, del
ivery as well as for materials
simple moveme
nts. Se
cond generation me
cha
nical arms are
equipped wit
h sensors a
nd ma
nipulators hav
e the envir
onme
nt there is a
certain amount
of
hen the mechani
cal arm is to use the
program as a ba
sis. Difference is that t
he robot bega
nd


当以隧道模式使用
IPSec
时，
其只为
IP
通讯提供封装。
使用
IPSec
隧道
模式主要是为了与其他不支持
IPSec
上的
L2TP
或
PPTP VPN
隧道技术的路由
器、网关或终端系统之间的相互操作。



SSL VPNSSL VPN, SSL
协议提供了数据私密性、端点验证、信息完整性等特
性。
SSL
协议由许多子协议组成，
其中两个主要的子协议是握手协议和记录 协议。
握手协议允许服务器

和客户端在应用协议传输第一个数据字节以前，
彼此确认，
协商一种加密算法和密码钥匙。
在数据传输期间，
记录协议利用握手协议生 成的
密钥加密和解密后来
交换

的数据。


< br>SSL
独立于应用，
因此任何一个应用程序都可以享受它的安全性而不必理会
执 行细节。
SSL
置身于网络结构体系的

传输层和应用层之间。
此外 ，
SSL
本身就
被几乎所有的
Web
浏览器支持。
这意味着 客户端不需要为了支持
SSL
连接安装额
外的软件。这两个特征就是
SSL< br>能

应用于
VPN
的关键点。



典型的
SSL VPN
应用如
OpenVPN,
是一个比较好的开源 软件。我们的产品提
供了
PPTP
和
OpenVPN
两种应用，PPTP
主要为那些经常外出移动或家庭办公的

用
户考虑；
而
OpenVPN
主要是针对企业异地两地总分公司之间的
VPN
不间断按需连
接，例如
ERP
在企业中的应用。



OpenVPN
允许参与建立
VPN
的单点使用预设的私钥，
第三 方证书，
或者用户
名
/
密码来进行身份验证。它大量使用了
Open SSL
加密库，以及
SSLv3/TLSv1
协
议。
OpenVP N
能在
Linux
、
xBSD
、
Mac OS X
与
Windows
2000/XP
上运行。它并不
是一个基于< br>Web
的
VPN
软件，也不与
IPsec
及其他
VP N
软件包兼容。



隧道加密


< br>OpenVPN
使用
OpenSSL
库加密数据与控制信息：
它使用了
OpesSSL
的加密以
及验证功能，
意味着，
它能够使用任何OpenSSL
支持的算法。
它提供了可选的数
据包
HMAC
功 能以提高连接的安全性。此外，
OpenSSL
的硬件加速也能提高它的
性能。



验证



OpenVPN
提供 了多种身份验证方式，用以确认参与连接双方的身份，包括：
预享私钥，
第三方证书以及用户名
/
密码组合。
预享密钥最为简单，
但同时它

只
能 用于建立点对点的
VPN
；基于
PKI
的第三方证书提供了最完善的功能，但 是需
要额外的精力去维护一个
PKI
证书体系。
OpenVPN2.0
后引入了用

户名
/
口令组
合的身份验证方式，
它可以省 略客户端证书，
但是仍有一份服务器证书需要被用
作加密
.


网络



OpenVPN
所有的通信都基于一个单一的< br>IP
端口，默认且推荐使用
UDP
协议
通讯，同时
TCP也被支持。
OpenVPN
连接能通过大多数的代理服务

器，并且能
m
anipulat
or control m
ode a
nd
programmabl
e controller
s introduction 2.1 S
elect
discussion with ma
nipulator
contr
ol 2.1.1 cl
assificati
on
of control relays
and discrete ele
ctronic
circuit
can
control
old i
ndustrial e
qui
pment,
but also more
common. Ma
inly these tw
o relatively chea
p and you ca
n meet the ol
d-fashioned,
simple (or
simple) i
ndustrial equipme
nt. So
he
can
see them now,
however t
hese tw
o contr
ol mode
s (relay and discrete ele
ctronic
circuits) are these fatal flaws: (1) cannot a
dapt to t
he complex l
ogic
control, (2) only for the
current
project, t
he lack
of com
patibi
lity
and (3) not reforming the sy
stem with e
qui
pment impr
ovements. S
pring for t
he development of China's modern i
ndustrial a
utomation technology the substa
ntial increase i
n the
level of industrial aut
omation, com
pleted t
he perfect relay of the
com
puter too mu
ch.
In terms
of controlling t
he
computer showed
his tw
o great advantage
s: (1) each of the
hardw
are ca
n be
installe
d on one
or
more micr
oprocessors; (2) the
official desig
ner of the
software writing
content control is all a
bout. Now in several ways in t
he context of industrial a
utomation ca
n often
be se
en i
n three ways: (1) Programmable Logica
l Controller (referred to as
IPC); (2) Distri
bute
d Control System (DCS for short), and (3) the Programmable
Logi
cal Controller (PLC for short). 2.1.2 PLC a
nd t
he IPC an
d DCS
contrast contrast 1, ea
ch of the three technologi
es of origi
ns a
nd
development requirement
s for fast data processing makes it inve
nted the com
puter. The me
n brought i
n terms of hardware there,
usi
ng a hig
h level of standardi
zation, ca
n use m
ore compat
ibility tool
s, is a ri
ch software resources, especially t
he ne
ed for immedia
cy in
operational systems. So the com
puter can ef
fectively control i
s used to
control and meet its spee
d, on the virtua
l model
, real-time a
nd i
n computational re
quireme
nts. Distri
bute
d system started wit
h a contr
ol system for industrial a
utomatic i
nstrume
nt
use
d to
contr
ol, whereas now it is
successfully deve
loped int
o
industrial control
computer use
d as a
central colle
ction a
nd
distri
bution system and transiti
on
of distributed
contr
ol system
in a
nalog
ue ha
ndli
ng, l
oop control,
has beg
un t
o reflect the use of a huge adva
ntage. Thoug
h distri
bute
d system has great adva
ntages in l
oop regulati
on,
but only as a means of conti
nuous
process
contr
ol. Optimization of PLC is the
corre
sponding relay nee
ds wa
s bor
n, its main
use i
n the w
ork order control, early
primary is repla
ced relay this hulking system, focused on the switch
controlli
ng the runni
ng order of functi
ons. Marked
by the micr
oprocessor i
n the early 1970 of the 20th
cent
ury emerged, micr
o-el
ectronics technol
ogy ha
s devel
ope
d rapi
dly,
people soon microel
ectronics processing technology w
ill be
used i
n the
Programmable
Logi
cal Controller (that is