Cisco filter question
Michel Py
michel at arneill-py.sacramento.ca.us
Fri Aug 22 17:02:11 UTC 2003
Instead of:
> set interface Null0
Use: set ip next-hop 10.255.255.254
_and_
ip route 10.255.255.254 255.255.255.255 Null0 name BLACKHOLE
Michel.
-----Original Message-----
From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On Behalf Of Geo.
Sent: Friday, August 22, 2003 9:17 AM
To: nanog at merit.edu
Subject: Cisco filter question
Perhaps one of you router experts can answer this question. When using the cisco specified filter
access-list 199 permit icmp any any echo
access-list 199 permit icmp any any echo-reply
route-map nachi-worm permit 10
! --- match ICMP echo requests and replies (type 0 & 8)
match ip address 199
! --- match 92 bytes sized packets
match length 92 92
! --- drop the packet
set interface Null0
interface <incoming-interface>
! --- it is recommended to disable unreachables
no ip unreachables
! --- if not using CEF, enabling ip route-cache flow is recommended
ip route-cache policy
! --- apply Policy Based Routing to the interface
ip policy route-map nachi-worm
why would it not stop this packet
15 1203.125000 0003E3956600 AMERIC6625D4 ICMP Echo: From 216.144.20.69 To 216.144.00.27 216.144.20.69 216.144.0.27 IP
FRAME: Base frame properties
FRAME: Time of capture = 8/22/2003 11:54:16.859
FRAME: Time delta from previous physical frame: 0 microseconds
FRAME: Frame number: 15
FRAME: Total frame length: 106 bytes
FRAME: Capture frame length: 106 bytes
FRAME: Frame data: Number of data bytes remaining = 106 (0x006A)
ETHERNET: ETYPE = 0x0800 : Protocol = IP: DOD Internet Protocol
ETHERNET: Destination address : 00C0B76625D4
ETHERNET: .......0 = Individual address
ETHERNET: ......0. = Universally administered address
ETHERNET: Source address : 0003E3956600
ETHERNET: .......0 = No routing information present
ETHERNET: ......0. = Universally administered address
ETHERNET: Frame Length : 106 (0x006A)
ETHERNET: Ethernet Type : 0x0800 (IP: DOD Internet Protocol)
ETHERNET: Ethernet Data: Number of data bytes remaining = 92 (0x005C)
IP: ID = 0x848; Proto = ICMP; Len: 92
IP: Version = 4 (0x4)
IP: Header Length = 20 (0x14)
IP: Precedence = Routine
IP: Type of Service = Normal Service
IP: Total Length = 92 (0x5C)
IP: Identification = 2120 (0x848)
IP: Flags Summary = 0 (0x0)
IP: .......0 = Last fragment in datagram
IP: ......0. = May fragment datagram if necessary
IP: Fragment Offset = 0 (0x0) bytes
IP: Time to Live = 124 (0x7C)
IP: Protocol = ICMP - Internet Control Message
IP: Checksum = 0x70D8
IP: Source Address = 216.144.20.69
IP: Destination Address = 216.144.0.27
IP: Data: Number of data bytes remaining = 72 (0x0048)
ICMP: Echo: From 216.144.20.69 To 216.144.00.27
ICMP: Packet Type = Echo
ICMP: Echo Code = 0 (0x0)
ICMP: Checksum = 0x82AA
ICMP: Identifier = 512 (0x200)
ICMP: Sequence Number = 7680 (0x1E00)
ICMP: Data: Number of data bytes remaining = 64 (0x0040)
00000: 00 C0 B7 66 25 D4 00 03 E3 95 66 00 08 00 45 00 .À·f%Ô..ã*f...E.
00010: 00 5C 08 48 00 00 7C 01 70 D8 D8 90 14 45 D8 90 .\.H..|.pØØ.EØ
00020: 00 1B 08 00 82 AA 02 00 1E 00 AA AA AA AA AA AA ....'ª....ªªªªªª
00030: AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA ªªªªªªªªªªªªªªªª
00040: AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA ªªªªªªªªªªªªªªªª
00050: AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA ªªªªªªªªªªªªªªªª
00060: AA AA AA AA AA AA AA AA AA AA ªªªªªªªªªª
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