Two-interface Router With NAT

2514 Router Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname horton ! enable secret 5 $1$GwRz$YS/82LXSYcgD1d5Nua9Ob1 enable password ww ! ip subne

2514 Router
  Current configuration:
  !
  version 12.0
  service timestamps debug uptime
  service timestamps log uptime
  no service password-encryption
  !
  hostname horton
  !
  enable secret 5 $1$GwRz$YS/82LXSYcgD1d5Nua9Ob1
  enable password ww
  !
  ip subnet-zero
  !
  ip inspect name ethernetin cuseeme timeout 3600
  ip inspect name ethernetin ftp timeout 3600
  ip inspect name ethernetin h323 timeout 3600
  ip inspect name ethernetin http timeout 3600
  ip inspect name ethernetin rcmd timeout 3600
  ip inspect name ethernetin realaudio timeout 3600
  ip inspect name ethernetin smtp timeout 3600
  ip inspect name ethernetin sqlnet timeout 3600
  ip inspect name ethernetin streamworks timeout 3600
  ip inspect name ethernetin tcp timeout 3600
  ip inspect name ethernetin tftp timeout 30
  ip inspect name ethernetin udp timeout 15
  ip inspect name ethernetin vdolive timeout 3600
  
  !
  interface Ethernet0
  ip address 20.20.20.2 255.255.255.0
  ip access-group 101 in
  no ip directed-broadcast
  ip nat inside
  ip inspect ethernetin in
  !
  interface Ethernet1
  no ip address
  no ip directed-broadcast
  shutdown
  !
  interface Serial0
  ip address 150.150.150.1 255.255.255.0
  ip access-group 112 in
  no ip directed-broadcast
  ip nat outside
  clockrate 4000000
  !
  interface Serial1
  no ip address
  no ip directed-broadcast
  shutdown
  !
  ip nat pool serialzero 150.150.150.3 150.150.150.255 netmask 255.255.255.0
  ip nat inside source list 1 pool serialzero
  ip classless
  ip route 0.0.0.0 0.0.0.0 150.150.150.2
  ip route 20.30.30.0 255.255.255.0 20.20.20.1
  !
  access-list 1 permit 20.0.0.0 0.255.255.255
  access-list 101 permit tcp 20.0.0.0 0.255.255.255 any
  access-list 101 permit udp 20.0.0.0 0.255.255.255 any
  access-list 101 permit icmp 20.0.0.0 0.255.255.255 any
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 unreachable
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 echo-reply
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 packet-too-big
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 time-exceeded
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 traceroute
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 administratively-prohibited
  access-list 112 permit icmp any 150.150.150.0 0.0.0.255 echo
  access-list 112 permit tcp host 150.150.150.2 host 150.150.150.1 eq telnet
  access-list 112 deny ip 127.0.0.0 0.255.255.255 any
  access-list 112 deny ip any any
  !
  line con 0
  transport input none
  line aux 0
  line vty 0 4
  password ww
  login
  !
  end
  
  
  关于ip inspect name
  if you deny SMTP mail on the external ACL, no external SMTP servers will ever be able to make a connection to the internal SMTP server.
  
  CBAC is totally independent of access lists - CBAC is associated with ACLs because one function of CBAC is to ensure return traffic of a
  session is permitted back to the source - however don't confuse CBAC by thinking ACLs are required. If you apply an inspect list to an interface, inspection takes place, no matter what ACLs are or are not in place. However, remember that ACLs are processed first, so the ACL must allow through the appropriate traffic to be passed thru to the inspection list.
  
  I'm guessing your config would look something like this:
  
  ! Internal Interface
  Interface e0 ip inspect WEB inbound
  
  ! External Interface
  Interface e1 ip access-group 100 in
  ip inspect SMTP inbound
  
  access-list 100 permit tcp any host x.x.x.x eq smtp
  access-list 100 deny ip any any
  
  ip inspect name WEB http
  ip inspect name WEB ftp
  ip inspect name WEB smtp
  ip inspect name WEB tcp
  ip inspect name WEB udp
  
  ip inspect name SMTP smtp
  
  On your external ACL, you must have an opening to allow SMTP in - there is no way CBAC can automatically do this for you as traffic is first processed by the ACL and must pass. So once the SMTP traffic is allowed
  in, it is passed to the inspection list SMTP, which applys SMTP protocol-based inspection (and opens up any ACLs if necessary - in this
  example this function is not required).
  
  Note that in this example you could place the SMTP inspection list on the internal interface in the outbound direction as well. This is a better placement option if you had say a DMZ interface that was also
  receiving SMTP mail for the internal SMTP server, as you would only require a single inspection point (outbound on the internal interface)
  rather than inbound on the external and DMZ interfaces.
  

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郑重声明:本文版权归原作者所有,转载文章仅为传播更多信息之目的,如作者信息标记有误,请第一时间联系我们修改或删除,多谢。

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