There is a difference as not both the source and destination port are the
same.
Lets say Station A wants to telnet to station B:
Source port A: >1024 Destination Port: 23 (telnet)
So to come back to your access-lists it DOES make a difference.
See this partial trace below:
Station A: 192.168.1.1 Station B: 192.168.1.22
In the trace you will see the 3-way handshake (Frame 1-3) and after that you
will see the Telnet negotiation starting
- - - - - - - - - - - - - - - - - - - - Frame
1 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
1 M [192.168.1.1] [192.168.1.22] 60 0:00:00.000
0.000.000 03/02/2001 08:48:19 AM TCP: D=23 S=2909 SYN SEQ=11781196 LEN=0
WIN=8192
DLC: ----- DLC Header -----
DLC:
DLC: Frame 1 arrived at 08:48:19.6300; frame size is 60 (003C hex)
bytes.
DLC: Destination = Station Cisco14A4BFA
DLC: Source = Station NGC 0DD6BC
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = 00
IP: 000. .... = routine
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 44 bytes
IP: Identification = 65107
IP: Flags = 4X
IP: .1.. .... = don't fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 128 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 7910 (correct)
IP: Source address = [192.168.1.1]
IP: Destination address = [192.168.1.22]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 2909
TCP: Destination port = 23 (Telnet)
TCP: Initial sequence number = 11781196
TCP: Next expected Seq number= 11781197
TCP: Data offset = 24 bytes
TCP: Flags = 02
TCP: ..0. .... = (No urgent pointer)
TCP: ...0 .... = (No acknowledgment)
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..1. = SYN
TCP: .... ...0 = (No FIN)
TCP: Window = 8192
TCP: Checksum = 244B (correct)
TCP:
TCP: Options follow
TCP: Maximum segment size = 1460
TCP:
- - - - - - - - - - - - - - - - - - - - Frame
2 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
2 [192.168.1.22] [192.168.1.1] 60 0:00:00.008
0.008.408 03/02/2001 08:48:19 AM TCP: D=2909 S=23 SYN ACK=11781197
SEQ=1056999666 LEN=0 WIN=4128
DLC: ----- DLC Header -----
DLC:
DLC: Frame 2 arrived at 08:48:19.6384; frame size is 60 (003C hex)
bytes.
DLC: Destination = Station NGC 0DD6BC
DLC: Source = Station Cisco14A4BFA
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = 00
IP: 000. .... = routine
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 44 bytes
IP: Identification = 0
IP: Flags = 0X
IP: .0.. .... = may fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 255 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 3864 (correct)
IP: Source address = [192.168.1.22]
IP: Destination address = [192.168.1.1]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 23 (Telnet)
TCP: Destination port = 2909
TCP: Initial sequence number = 1056999666
TCP: Next expected Seq number= 1056999667
TCP: Acknowledgment number = 11781197
TCP: Data offset = 24 bytes
TCP: Flags = 12
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..1. = SYN
TCP: .... ...0 = (No FIN)
TCP: Window = 4128
TCP: Checksum = 6C27 (correct)
TCP:
TCP: Options follow
TCP: Maximum segment size = 1460
TCP:
- - - - - - - - - - - - - - - - - - - - Frame
3 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
3 [192.168.1.1] [192.168.1.22] 60 0:00:00.009
0.000.762 03/02/2001 08:48:19 AM TCP: D=23 S=2909 ACK=1056999667
WIN=8760
DLC: ----- DLC Header -----
DLC:
DLC: Frame 3 arrived at 08:48:19.6391; frame size is 60 (003C hex)
bytes.
DLC: Destination = Station Cisco14A4BFA
DLC: Source = Station NGC 0DD6BC
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = 00
IP: 000. .... = routine
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 40 bytes
IP: Identification = 65363
IP: Flags = 4X
IP: .1.. .... = don't fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 128 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 7814 (correct)
IP: Source address = [192.168.1.1]
IP: Destination address = [192.168.1.22]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 2909
TCP: Destination port = 23 (Telnet)
TCP: Sequence number = 11781197
TCP: Next expected Seq number= 11781197
TCP: Acknowledgment number = 1056999667
TCP: Data offset = 20 bytes
TCP: Flags = 10
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 0... = (No push)
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 8760
TCP: Checksum = 71CC (correct)
TCP: No TCP options
TCP:
- - - - - - - - - - - - - - - - - - - - Frame
4 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
4 [192.168.1.22] [192.168.1.1] 66 0:00:00.014
0.005.557 03/02/2001 08:48:19 AM Telnet: R PORT=2909 IAC Will Echo
DLC: ----- DLC Header -----
DLC:
DLC: Frame 4 arrived at 08:48:19.6447; frame size is 66 (0042 hex)
bytes.
DLC: Destination = Station NGC 0DD6BC
DLC: Source = Station Cisco14A4BFA
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = C0
IP: 110. .... = internetwork control
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 52 bytes
IP: Identification = 1
IP: Flags = 0X
IP: .0.. .... = may fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 255 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 379B (correct)
IP: Source address = [192.168.1.22]
IP: Destination address = [192.168.1.1]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 23 (Telnet)
TCP: Destination port = 2909
TCP: Sequence number = 1056999667
TCP: Next expected Seq number= 1056999679
TCP: Acknowledgment number = 11781197
TCP: Data offset = 20 bytes
TCP: Flags = 18
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 1... = Push
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 4128
TCP: Checksum = 70B4 (correct)
TCP: No TCP options
TCP: [12 Bytes of data]
TCP:
Telnet: ----- Telnet -----
Telnet:
Telnet: IAC Will Echo
Telnet: IAC Will Suppress go-ahead
Telnet: IAC Do Terminal-type
Telnet: IAC Do Negotiate about window size
Telnet:
Telnet:
- - - - - - - - - - - - - - - - - - - - Frame
5 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
5 [192.168.1.1] [192.168.1.22] 60 0:00:00.016
0.002.113 03/02/2001 08:48:19 AM Telnet: C PORT=2909 IAC Do Suppress
go-ahead
DLC: ----- DLC Header -----
DLC:
DLC: Frame 5 arrived at 08:48:19.6468; frame size is 60 (003C hex)
bytes.
DLC: Destination = Station Cisco14A4BFA
DLC: Source = Station NGC 0DD6BC
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = 00
IP: 000. .... = routine
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 43 bytes
IP: Identification = 84
IP: Flags = 4X
IP: .1.. .... = don't fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 128 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 7711 (correct)
IP: Source address = [192.168.1.1]
IP: Destination address = [192.168.1.22]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 2909
TCP: Destination port = 23 (Telnet)
TCP: Sequence number = 11781197
TCP: Next expected Seq number= 11781200
TCP: Acknowledgment number = 1056999679
TCP: Data offset = 20 bytes
TCP: Flags = 18
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 1... = Push
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 8748
TCP: Checksum = 6EC3 (correct)
TCP: No TCP options
TCP: [3 Bytes of data]
TCP:
Telnet: ----- Telnet -----
Telnet:
Telnet: IAC Do Suppress go-ahead
Telnet:
Telnet:
- - - - - - - - - - - - - - - - - - - - Frame
6 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
6 [192.168.1.22] [192.168.1.1] 96 0:00:00.028
0.011.298 03/02/2001 08:48:19 AM Telnet: R PORT=2909 <0D0A0D0A>User
Access Verification<0D0A0D0A>Pa...
DLC: ----- DLC Header -----
DLC:
DLC: Frame 6 arrived at 08:48:19.6581; frame size is 96 (0060 hex)
bytes.
DLC: Destination = Station NGC 0DD6BC
DLC: Source = Station Cisco14A4BFA
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = C0
IP: 110. .... = internetwork control
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 82 bytes
IP: Identification = 2
IP: Flags = 0X
IP: .0.. .... = may fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 255 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 377C (correct)
IP: Source address = [192.168.1.22]
IP: Destination address = [192.168.1.1]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 23 (Telnet)
TCP: Destination port = 2909
TCP: Sequence number = 1056999679
TCP: Next expected Seq number= 1056999721
TCP: Acknowledgment number = 11781200
TCP: Data offset = 20 bytes
TCP: Flags = 18
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 1... = Push
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 4125
TCP: Checksum = DA25 (correct)
TCP: No TCP options
TCP: [42 Bytes of data]
TCP:
Telnet: ----- Telnet -----
Telnet:
Telnet: <0D0A0D0A>User Access Verification<0D0A0D0A>Password:
Telnet:
- - - - - - - - - - - - - - - - - - - - Frame
7 - - - - - - - - - - - - - - - - - - - -
Frame Status Source Address Dest. Address Size Rel. Time Delta
Time Abs. Time Summary
7 [192.168.1.1] [192.168.1.22] 75 0:00:00.028
0.000.765 03/02/2001 08:48:19 AM Telnet: C PORT=2909 IAC Do Echo
DLC: ----- DLC Header -----
DLC:
DLC: Frame 7 arrived at 08:48:19.6589; frame size is 75 (004B hex)
bytes.
DLC: Destination = Station Cisco14A4BFA
DLC: Source = Station NGC 0DD6BC
DLC: Ethertype = 0800 (IP)
DLC:
IP: ----- IP Header -----
IP:
IP: Version = 4, header length = 20 bytes
IP: Type of service = 00
IP: 000. .... = routine
IP: ...0 .... = normal delay
IP: .... 0... = normal throughput
IP: .... .0.. = normal reliability
IP: .... ..0. = ECT bit - transport protocol will ignore the CE
bit
IP: .... ...0 = CE bit - no congestion
IP: Total length = 61 bytes
IP: Identification = 340
IP: Flags = 4X
IP: .1.. .... = don't fragment
IP: ..0. .... = last fragment
IP: Fragment offset = 0 bytes
IP: Time to live = 128 seconds/hops
IP: Protocol = 6 (TCP)
IP: Header checksum = 75FF (correct)
IP: Source address = [192.168.1.1]
IP: Destination address = [192.168.1.22]
IP: No options
IP:
TCP: ----- TCP header -----
TCP:
TCP: Source port = 2909
TCP: Destination port = 23 (Telnet)
TCP: Sequence number = 11781200
TCP: Next expected Seq number= 11781221
TCP: Acknowledgment number = 1056999721
TCP: Data offset = 20 bytes
TCP: Flags = 18
TCP: ..0. .... = (No urgent pointer)
TCP: ...1 .... = Acknowledgment
TCP: .... 1... = Push
TCP: .... .0.. = (No reset)
TCP: .... ..0. = (No SYN)
TCP: .... ...0 = (No FIN)
TCP: Window = 8706
TCP: Checksum = 9A94 (correct)
TCP: No TCP options
TCP: [21 Bytes of data]
TCP:
Telnet: ----- Telnet -----
Telnet:
Telnet: IAC Do Echo
Telnet: IAC Do Suppress go-ahead
Telnet: IAC Will Terminal-type
Telnet: IAC Will Negotiate about window size
Telnet: IAC SB ...
Telnet:
Telnet:
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
jeongwoo park
Sent: Friday, March 02, 2001 3:09 AM
To: [EMAIL PROTECTED]
Subject: Can anyone clarify the difference of these two?
hi all
Can anyone clarify the difference of these two?
access-list 101 permit tcp host 192.168.1.52 eq telnet any
access-list 101 permit tcp host 192.168.1.52 any eq telnet
--
jeongwoo
_________________________________
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
_________________________________
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
