Well, I said I couldn't remember under exactly what situations it happens!? And, I understand Brad's comment now. He thought I was saying "of course not" to his comment. I would never say that to a CCIE. ;-) I was saying "of course not" to his question "are you saying...." Sorry, I'm in such a rush..... Priscilla At 12:16 AM 8/27/01, John Hardman wrote: >Hi > >I can't believe I am challenging Priscilla! > >I just tried what you are talking about, i.e. that the ACL on the router >does not effect the traffic generated by the router it's self. > >I created an extended ACL to block all ICMP traffic and applied it to E0 as >both IN and OUT. Before appling the ACL I can ping just fine to any host on >the network and any host on the network can ping the router. After Appling >the ACL I am not able to ping from the router, or to the router. > >I am running 11.1 IOS, maybe it would yield different results with a >different IOS version. What IOS and platform did you see this behavior? > >Here's my config. > >Windoze PC 192.168.10.50 --- E0 Router2 192.168.10.20 >RedHat PC 192.168.10.2 > >-------------Router config-------------- >Current configuration: >! >version 11.1 >service udp-small-servers >service tcp-small-servers >! >hostname C2501-R2 >! >enable secret 5 XXX >enable password none >! >ip subnet-zero >! >interface Ethernet0 > ip address 192.168.10.20 255.255.255.0 > ip access-group 100 in > ip access-group 100 out > no ip mroute-cache > no ip route-cache >! >interface Serial0 > ip address 192.168.50.1 255.255.255.252 > no ip mroute-cache > encapsulation ppp > no ip route-cache >! >interface Serial1 > no ip address > no ip mroute-cache > no ip route-cache > shutdown >! >ip classless >logging buffered >access-list 100 deny icmp any any >access-list 100 permit ip any any >! >line con 0 > exec-timeout 0 0 >line aux 0 > transport input all >line vty 0 4 > exec-timeout 0 0 > password XXXX > login >! >end > >-----------Router Config-------------- > >-----------Ping results----------------- > >C2501-R2#ping 192.168.10.50 > >Type escape sequence to abort. >Sending 5, 100-byte ICMP Echoes to 192.168.10.50, timeout is 2 seconds: >..... >Success rate is 0 percent (0/5) >C2501-R2#conf t >Enter configuration commands, one per line. End with CNTL/Z. >C2501-R2(config)#int e0 >C2501-R2(config-if)#no ip access-group 100 in >C2501-R2(config-if)#no ip access-group 100 out >C2501-R2(config-if)#^Z >C2501-R2# >%SYS-5-CONFIG_I: Configured from console by console >C2501-R2#ping 192.168.10.50 > >Type escape sequence to abort. >Sending 5, 100-byte ICMP Echoes to 192.168.10.50, timeout is 2 seconds: >!!!!! >Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms >C2501-R2# > >Windoze Ping with ACL ---- >C:\>ping 192.168.10.20 > >Pinging 192.168.10.20 with 32 bytes of data: > >Reply from 192.168.10.20: Destination net unreachable. >Reply from 192.168.10.20: Destination net unreachable. >Reply from 192.168.10.20: Destination net unreachable. >Reply from 192.168.10.20: Destination net unreachable. > >Ping statistics for 192.168.10.20: > Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), >Approximate round trip times in milli-seconds: > Minimum = 0ms, Maximum = 0ms, Average = 0ms > >Windoze Ping without ACL ---- > >C:\>ping 192.168.10.20 > >Pinging 192.168.10.20 with 32 bytes of data: > >Reply from 192.168.10.20: bytes=32 time wrote in message >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > I know it's not what you said. What you said was obvious. I guess it comes > > about because I said to test with end devices. Router A is acting like an > > end device in your example. I should have been more clear. > > > > What is not obvious is that ACLs on Router B do not apply to pings to and > > from Router B. Every newbie has probably been bitten by that one, > > especially in simple labs. > > > > Priscilla > > > > At 09:42 PM 8/26/01, Brad Ellis wrote: > > >Priscilla, that's not what I said. Here's what I said: > > > > > >"...pings sent by one router will not be filtered by another router? " > > > > > >Hence my diagram for further explanation: > > > > > >Router A -=- Router B -=- Device A > > >(-=- can be ethernet x-over, serial back-to-back, etc) > > > > > >An ACL is applied on Router B's interface (applied inbound) that is > > >connected to Router A. What I originally said, and continue to say, is >that > > >Router B will most certainly block packets (pings or whatever) coming >from > > >Router A...and it is irrelevant if Router A is a router or a host device. > > >The ACL on Router B doesnt care if the device sending packets is a router >or > > >an end host device! > > > > > >If Router B was initiating the ping and Router B had the ACL applied, >that > > >would be a different story. > > > > > >ttyl, > > >-Brad Ellis > > >CCIE#5796 > > >[EMAIL PROTECTED] > > >used Cisco: www.optsys.net > > > > > >""Priscilla Oppenheimer"" wrote in message > > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > At 08:06 PM 8/26/01, Brad Ellis wrote: > > > > >Priscilla, > > > > > > > > > >Are you saying that pings sent by one router will not be filtered by > > >another > > > > >router? I beg to differ. > > > > > > > > Of course not. Pings sent by the router where the ACL is configured >are > > >not > > > > affected by the ACL. Try it. > > > > > > > > Priscilla > > > > > > > > > > > > >-Brad > > > > > > > > > >""Priscilla Oppenheimer"" wrote in message > > > > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > > > At 06:26 PM 8/26/01, Brad Ellis wrote: > > > > > > >Sami, > > > > > > > > > > > > > >You'll need to give more info than that. The router does not >care > > if > > > > the > > > > > > >packets are originated from a host or another router. It will > > filter > > > > > > >packets based on packet information, ie, source address, >destination > > > > > > >address, port #... > > > > > > > > > > > > This filtering happens as part of the packet-forwarding process. > > >Packets > > > > > > sent by the router (such as pings) may not go through this >process. > > >Sorry > > > > > > that I don't have the details, but I have run into surprising >results > > >in > > > > a > > > > > > lab environment when testing access lists from a router. You need >to > > >test > > > > > > them from end hosts. > > > > > > > > > > > > I can't believe I'm challenging a CCIE, ;-) but I was afraid >nobody > > >else > > > > > > would, and I think the question bears more research. > > > > > > > > > > > > Priscilla > > > > > > > > > > > > >Are you saying the router wont filter packets originated from the > > >router > > > > > > >itself? How are your access-lists applied? Inbound or Outbound? > > >What > > > > >are > > > > > > >you trying to filter? Explain your situation a little better, >and > > > > >include > > > > > > >your access-list if you so desire. > > > > > > > > > > > > > >-Brad Ellis > > > > > > >CCIE#5796 > > > > > > >[EMAIL PROTECTED] > > > > > > >used Cisco: www.optsys.net > > > > > > > > > > > > > >""sami natour"" wrote in message > > > > > > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > > > > > Hi All , > > > > > > > > When I made standard access list I discoverd that it > > > > > > > > prevented packets originated form PC's and host but > > > > > > > > not packets originated from other routers.Any idea why > > > > > > > > this will happen. > > > > > > > > > > > > > > > > Best Regards , > > > > > > > > sami , > > > > > > > > > > > > > > > > > > > > > > > > __________________________________________________ > > > > > > > > Do You Yahoo!? > > > > > > > > Make international calls for as low as $.04/minute with Yahoo! > > > > >Messenger > > > > > > > > http://phonecard.yahoo.com/ > > > > > > ________________________ > > > > > > > > > > > > Priscilla Oppenheimer > > > > > > http://www.priscilla.com > > > > ________________________ > > > > > > > > Priscilla Oppenheimer > > > > http://www.priscilla.com > > ________________________ > > > > Priscilla Oppenheimer > > http://www.priscilla.com ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=17413&t=17413 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
