© 1999, cisco systems, inc. icnd—10-1 chapter 8 ip 访问控制列表

© 1999, Cisco Systems, Inc. www.cisco.com ICND—10-1

Chapter 8

IP 访问控制列表


FDDI

• 当网络增长时，管理 IP 网络流量

TokenRing

为什么使用 IP 访问控制列表 ?为什么使用 IP 访问控制列表 ?


FDDI

172.16.0.0

172.17.0.0

TokenRing

Internet

• 当网络增长时，管理 IP 网络流量• 当数据包经过 Router 时，对数据进行筛选

为什么使用 IP 访问控制列表 ?为什么使用 IP 访问控制列表 ?


IP 访问控制列表应用

• Permit or deny packets moving through the router

• Permit or deny vty access to or from the router

• Without access lists all packets could be transmitted onto all parts of your network

Virtual terminal line access (IP)

Transmission of packets on an interface


• 标准访问控制列表– 按照源地址控制– 通常允许或拒绝整个协议栈

OutgoingPacket

E0

S0

IncomingPacket

Access List Processes

Permit?

Source

访问控制列表访问控制列表


• 标准访问控制列表– 检验源地址– 通常允许或拒绝整个协议栈

• 扩展访问控制列表– 检验源地址、目的地址– 通常允许或拒绝某个单独的协议

OutgoingPacket

E0

S0

IncomingPacket


Permit?

Sourceand

Destination

Protocol



• 标准访问控制列表– 检验源地址– 通常允许或拒绝整个协议栈

• 扩展访问控制列表– 检验源地址、目的地址– 通常允许或拒绝某个单独的协议

• Inbound 和 Outbound 两个方向

OutgoingPacket

E0

S0

IncomingPacket


Permit?

Sourceand

Destination

Protocol



InboundInterfacePackets

N

Y

Packet Discard Bucket

ChooseInterface

NAccessList

?

RoutingTable Entry

?

Y

Outbound Interfaces

Packet

S0

Outbound 访问控制列表Outbound 访问控制列表


Outbound Interfaces

Packet

N

Y


ChooseInterface

RoutingTable Entry

?N Packet

TestAccess ListStatements

Permit?

Y


AccessList

?

Y

S0

E0



Notify Sender


If no access list statement matches then discard the packet

N

Y


ChooseInterface

RoutingTable Entry

?N

Y

TestAccess ListStatements

Permit?

Y

AccessList

?

Discard Packet

N

Outbound Interfaces

Packet

Packet

S0

E0



A List of Tests: Deny or PermitA List of Tests: Deny or Permit

Packets to interfacesin the access group


Y

Interface(s)

Destination

Deny

Deny

Y

MatchFirstTest

?

Permit



Packets to Interface(s)in the Access Group


Y

Interface(s)

Destination

Deny

Deny

Y

MatchFirstTest

?

Permit

N

Deny PermitMatchNext

Test(s)?

YY

• The order of access list statements controls testing





Y

Interface(s)

Destination

Deny

Deny

Y

MatchFirstTest

?

Permit

N


Test(s)?

DenyMatchLastTest

?

YY

N

YYPermit





Y

Interface(s)

Destination

Deny

Y

MatchFirstTest

?

Permit

N


Test(s)?

DenyMatchLastTest

?

YY

N

YYPermit

Implicit Deny

If no matchdeny allDeny

N


访问控制列表配置的一般原则访问控制列表配置的一般原则

• 访问控制列表编号指明每接口、每协议、每方向一个访问控制列表。• 最严格的语句放在列表最上面。• 访问控制列表末尾有一个隐含的拒绝。• 先创建访问控制列表，后绑定到接口。• 访问控制列表只过滤通过 router 的流量 ; 不过滤由此

router 自己发出的数据。


访问控制列表配置命令

Step 1: 设置访问控制列表语句 ( 可以有多条语句 )

access-list access-list-number { permit | deny } { test conditions }

Router(config)#


Step 1: 设置访问控制列表语句 ( 可以有多条语句 )

Router(config)#

Step 2: 在指定的接口启用访问控制列表

{ protocol } access-group access-list-number {in | out} Router(config-if)#

访问控制列表配置命令

IP Access lists are numbered 1-99 or 100-199

access-list access-list-number { permit | deny } { test conditions }


访问控制列表类型访问控制列表类型

Number Range/IdentifierAccess List Type

IP 1-99Standard

• Standard IP lists (1 to 99) test conditions of all IP packets from source addresses


Number Range/IdentifierAccess List Type


IP 1-99100-199

StandardExtended


• Extended IP lists (100 to 199) can test conditions of source and destination addresses, specific TCP/IP protocols, and destination ports


Number Range/Identifier

IP 1-99100-199Name (Cisco IOS 11.2 and later)

800-899900-9991000-1099Name (Cisco IOS 11.2. F and later)

StandardExtendedSAP filtersNamed

StandardExtendedNamed

Access List Type

IPX



• Extended IP lists (100 to 199) can test conditions of source and destination addresses, specific TCP/IP protocols, and destination ports

• Other access list number ranges test conditions for other networking protocols


SourceAddress

Segment(for example, TCP header)

DataPacket(IP header)

Frame Header(for example, HDLC)

Deny Permit

Useaccess

list statements1-99

标准访问控制列表标准访问控制列表


DestinationAddress

SourceAddress

Protocol

PortNumber

Segment(for example, TCP header)

DataPacket(IP header)

Frame Header(for example, HDLC)

Useaccess

list statements1-99 or 100-199 to

test thepacket Deny Permit

An Example from a TCP/IP Packet

扩展访问控制列表扩展访问控制列表


• 0 ：检查相对应的地址位• 1 ：忽略相对应的地址位

do not check address (ignore bits in octet)

=0 0 1 1 1 1 1 1

128 64 32 16 8 4 2 1

=0 0 0 0 0 0 0 0

=0 0 0 0 1 1 1 1

=1 1 1 1 1 1 0 0

=1 1 1 1 1 1 1 1

Octet bit position and address value for bit

ignore last 6 address bits

check all address bits(match all)

ignore last 4 address bits

check last 2 address bits

Examples

应用 Wildcard Bits 指定 IP 地址应用 Wildcard Bits 指定 IP 地址


• Example 172.30.16.29 0.0.0.0 checks all the address bits

• Abbreviate this wildcard mask using the IP address preceded by the keyword host (host 172.30.16.29)

Test conditions: Check all the address bits (match all)

172.30.16.29

0.0.0.0(checks all bits)

An IP host address, for example:

Wildcard mask:

应用 Wildcard Bits 指定单个 IP 地址

应用 Wildcard Bits 指定单个 IP 地址


• Accept any address: 0.0.0.0 255.255.255.255

• Abbreviate the expression using the keyword any

Test conditions: Ignore all the address bits (match any)

0.0.0.0

255.255.255.255(ignore all)

Any IP address

Wildcard mask:

应用 Wildcard Bits 指定任意 IP 地址

应用 Wildcard Bits 指定任意 IP 地址


Check for IP subnets 172.30.16.0/24 to 172.30.31.0/24

Network Network .host 172.30.16172.30.16.0

00 00 00 11 0 0 0 0Wildcard mask: 0 0 0 0 1 1 1 1

|<---- match ---->|<----- don’t care ----->|

0 0 0 1 0 0 0 0 = 16

0 0 0 1 0 0 0 1 = 17

0 0 0 1 0 0 1 0 = 18

: :

0 0 0 1 1 1 1 1 = 31

Address and wildcard mask:

172.30.16.0 0.0.15.255

应用 Wildcard Bits 指定一个 IP 地址范围

应用 Wildcard Bits 指定一个 IP 地址范围

© 1999, Cisco Systems, Inc. www.cisco.com 10-27

配置标准访问控制列表


配置标准访问控制列表配置标准访问控制列表

access-list access-list-number {permit|deny} source [mask]

Router(config)#

• Sets parameters for this list entry

• IP standard access lists use 1 to 99

• Default wildcard mask = 0.0.0.0

• “no access-list access-list-number” removes entire access-list


access-list access-list-number {permit|deny} source [mask]

Router(config)#

• Activates the list on an interface

• Sets inbound or outbound testing

• Default = Outbound

• “no ip access-group access-list-number” removes access-list from the interface

Router(config-if)#

ip access-group access-list-number { in | out }


• IP standard access lists use 1 to 99

• Default wildcard mask = 0.0.0.0

• “no access-list access-list-number” removes entire access-list

配置标准访问控制列表配置标准访问控制列表


172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

配置标准访问控制列表Example 1


access-list 1 permit 172.16.0.0 0.0.255.255(implicit deny all - not visible in the list)(access-list 1 deny 0.0.0.0 255.255.255.255)


Permit 只允许本地网络的访问

access-list 1 permit 172.16.0.0 0.0.255.255(implicit deny all - not visible in the list)(access-list 1 deny 0.0.0.0 255.255.255.255)

interface ethernet 0ip access-group 1 outinterface ethernet 1ip access-group 1 out

172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0



Deny 一个特定主机



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

access-list 1 deny 172.16.4.13 0.0.0.0




172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0


access-list 1 deny 172.16.4.13 0.0.0.0 access-list 1 permit 0.0.0.0 255.255.255.255(implicit deny all)(access-list 1 deny 0.0.0.0 255.255.255.255)


access-list 1 deny 172.16.4.13 0.0.0.0 access-list 1 permit 0.0.0.0 255.255.255.255(implicit deny all)(access-list 1 deny 0.0.0.0 255.255.255.255)

interface ethernet 0ip access-group 1 out



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0



Deny 一个特定子网



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

access-list 1 deny 172.16.4.0 0.0.0.255access-list 1 permit any(implicit deny all)(access-list 1 deny 0.0.0.0 255.255.255.255)


access-list 1 deny 172.16.4.0 0.0.0.255access-list 1 permit any(implicit deny all)(access-list 1 deny 0.0.0.0 255.255.255.255)




172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

Deny 一个特定子网


用访问控制列表控制VTY 线路访问


过滤 VTY 访问过滤 VTY 访问

• 5 条 VTY 线路 (0 —— 4)

• 筛选能够到达 Router 端口的地址• 筛选 Router vty out 方向的流量

0 1 2 3 4

Virtual ports (vty 0 through 4)

Physical port e0 (Telnet)Console port (direct connect)

console e0


如何控制 vty 访问如何控制 vty 访问

0 1 2 3 4

Virtual ports (vty 0 through 4)

Physical port (e0) (Telnet)

• Setup IP address filter with standard access list statement

• Use line configuration mode to filter access with the access-class command

• Set identical restrictions on all vtys

Router#

e0


Virtual Terminal Line Commands

Virtual Terminal Line Commands

• Enters configuration mode for a vty or vty range

• Restricts incoming or outgoing vty connections for address in the access list

access-class access-list-number {in|out}

line vty#{vty# | vty-range}

Router(config)#

Router(config-line)#


Virtual Terminal Access Example

Virtual Terminal Access Example

Permits only hosts in network 192.89.55.0 to connect to the router’s vtys

access-list 12 permit 192.89.55.0 0.0.0.255

!

line vty 0 4

access-class 12 in

Controlling Inbound Access


配置扩展访问控制列表


标准 VS 扩展访问控制列表标准 VS 扩展访问控制列表

Standard Extended

基于源地址筛选基于源地址、目的地址筛选

Permit 、 deny 整个 TCP/IP 协议栈 .

可以指定某个 TCP/IP 协议与端口号

编号 100~199编号 1~99


配置扩展访问控制列表配置扩展访问控制列表

Router(config)#


access-list access-list-number { permit | deny } protocol source source-wildcard [operator port] destination destination-wildcard [ operator port ] [ established ] [log]


Router(config-if)# ip access-group access-list-number { in | out }

配置扩展访问控制列表配置扩展访问控制列表

• Activates the extended list on an interface


Router(config)# access-list access-list-number { permit | deny } protocol source source-wildcard [operator port] destination destination-wildcard [ operator port ] [ established ] [log]


• Deny FTP from subnet 172.16.4.0 to subnet 172.16.3.0 out of E0

• Permit all other traffic

172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

扩展访问控制列表Example 1


access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 21access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 20


• Deny FTP from subnet 172.16.4.0 to subnet 172.16.3.0 out of E0

• Permit all other traffic



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 21access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 20access-list 101 permit ip any any(implicit deny all)(access-list 101 deny ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255)


access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 21access-list 101 deny tcp 172.16.4.0 0.0.0.255 172.16.3.0 0.0.0.255 eq 20access-list 101 permit ip any any(implicit deny all)(access-list 101 deny ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255)


• Deny FTP from subnet 172.16.4.0 to subnet 172.16.3.0 out of E0 • Permit all other traffic



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0


• Deny only Telnet from subnet 172.16.4.0 out of E0• Permit all other traffic



172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

access-list 101 deny tcp 172.16.4.0 0.0.0.255 any eq 23





172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0

access-list 101 deny tcp 172.16.4.0 0.0.0.255 any eq 23access-list 101 permit ip any any(implicit deny all)


access-list 101 deny tcp 172.16.4.0 0.0.0.255 any eq 23access-list 101 permit ip any any(implicit deny all)





172.16.3.0 172.16.4.0

172.16.4.13E0

S0E1

Non-172.16.0.0


• 将扩展访问控制列表靠近源地址• 将标准访问控制列表靠近目的地址

E0

E0

E1

S0

To0

S1S0

S1

E0

E0TokenRing

BB

AACC

在哪里放置访问控制列表在哪里放置访问控制列表

Recommended:

DD


wg_ro_a#show ip int e0Ethernet0 is up, line protocol is up Internet address is 10.1.1.11/24 Broadcast address is 255.255.255.255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is disabled Outgoing access list is not set Inbound access list is 1 Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is disabled IP Feature Fast switching turbo vector IP multicast fast switching is enabled IP multicast distributed fast switching is disabled <text ommitted>

验证访问控制列表验证访问控制列表


查看访问控制列表语句查看访问控制列表语句

wg_ro_a#show access-lists Standard IP access list 1 permit 10.2.2.1 permit 10.3.3.1 permit 10.4.4.1 permit 10.5.5.1Extended IP access list 101 permit tcp host 10.22.22.1 any eq telnet permit tcp host 10.33.33.1 any eq ftp permit tcp host 10.44.44.1 any eq ftp-data

wg_ro_a#show {protocol} access-list {access-list number}

wg_ro_a#show access-lists {access-list number}

© 1999, cisco systems, inc. icnd—10-1 chapter 8 ip 访问控制列表

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