From: Jason Madsen (madsen.jason@gmail.com)
Date: Sat Nov 08 2008 - 23:06:52 ARST
Hi Bob, I'm not sure if that's the case with CBAC or not, but I did try
extending the topology a bit more and sourced the request from another
connected device, but had the same exact results. Telnet and ICMP worked
just fine, but TFTP wouldn't work at all.
Along with my debugs I enabled alerts and auditing and really didn't get any
more info' that way either.
Thanks,
Jason
On Sat, Nov 8, 2008 at 5:58 PM, Bob Sinclair <bob@bobsinclair.net> wrote:
> Jason,
>
> I looks to me like you are generating traffic from the device that is doing
> the inspecting. I do not believe that CBAC can inspect connections that
> terminate on the router; they must go through the router. Try tftp from a
> device "inside" R0.
>
> HTH,
>
> -Bob Sinclair CCIE 10427 CCSI 30427
> www.netmasterclass.net
>
>
> Jason Madsen wrote:
>
>> Hello All,
>>
>> ...quick question. There are quite a lot of CBAC options available to
>> use,
>> but overall it's a pretty straightforward technology...at least that's
>> what
>> I've always thought and experienced until now. For whatever reason(s)
>> CBAC
>> doesn't seem to be allowing me to tftp. Here's the basic config' I was
>> using:
>>
>> *R1:*
>>
>> tftp-server flash:test.txt
>>
>> int f0/0
>> desc link to R0
>> ip add 1.1.1.2 255.255.255.252
>>
>> *R0:*
>>
>> int f0/0
>> desc link to R1
>> ip add 1.1.1.1 255.255.255.252
>> ip access-group 100 in
>> ip inspect TEST out
>>
>> access-list 100 deny ip any any
>>
>> ip inspect name TEST tcp router-traffic
>> ip inspect name TEST telnet
>> ip inspect name TEST tftp
>> ip inspect name TEST udp router-traffic
>> ip inspect name TEST icmp router-traffic
>>
>>
>>
>> I am successfully able to telnet and ping to R1, but I can't get a file
>> via
>> tftp. i'm able to get a file via tftp just fine when ACL 100 is removed,
>> but I can't seem to get CBAC make an opening for it. I do know that tftp
>> uses UDP (port 69) and i am using dynamips. do you think it's possible
>> that
>> dynamips is too slow for CBAC to work with its default timers and such?
>> doesn't seem like it has anything to do with it to me...without ACL 100
>> applied, the file seems to transfer across very quickly.
>>
>>
>> debug ip inspect detail output when trying to tftp:
>>
>> R0(config)#do copy tftp flash
>> Address or name of remote host [1.1.1.2]?
>> Source filename [test.txt]?
>> Destination filename [test.txt]?
>> Accessing tftp://1.1.1.2/test.txt...
>> *Mar 1 03:45:29.867: CBAC: Finding pregen session for src_tableid:0,
>> src_addr:1
>> .1.1.1, src_port:55559, dst_tableid:0, dst_addr:1.1.1.2, dst_port:69
>> %Error opening tftp://1.1.1.2/test.txt (Timed out)
>>
>> Here's an attempt with ACL 100 removed to validate tftp functionality:
>>
>> R0(config-if)#do copy tftp flash
>> Address or name of remote host [1.1.1.2]?
>> Source filename [test.txt]?
>> Destination filename [test.txt]?
>> Accessing tftp://1.1.1.2/test.txt...
>> Erase flash: before copying? [confirm]
>> Erasing the flash filesystem will remove all files! Continue? [confirm]
>> Erasing device... eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ...erasedee
>> Erase of flash: complete
>> Loading test.txt from 1.1.1.2 (via FastEthernet0/0): !
>> [OK - 1670 bytes]
>>
>> Verifying checksum... OK (0x535)
>> 1670 bytes copied in 1.356 secs (1232 bytes/sec)
>> R0(config-if)#
>>
>>
>> any ideas?
>>
>> Thanks,
>> Jason
>>
>>
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