That's correct. It's just randomized. Cisco just defaults to the one I
listed. The end goal (how to measure success) is receiving an ICMP
port-unreachable message rather than an ICMP ttl-exceeded!
Scott
-----Original Message-----
From: Stephen Gill [mailto:gillsr@yahoo.com]
Sent: Wednesday, November 28, 2001 11:46 PM
To: 'micky'; swm@emanon.com
Cc: cisco-nsp@puck.nether.net
Subject: RE: [nsp] Cisco ios traceroute VS. windows tracert ?
No.
I think you should reach TCP/IP Vol 1 by Richard Stevens. His
traceroute chapter explains it pretty well. Here’s a quote: “Traceroute
sends UDP datagrams to the destination host, but it chooses the
destination UDP port number to be an unlikely value (larger than
30,000), making it improbable that an application at the destination is
using that port. This causes the destination host's UDP module to
generate an ICMP "port unreachable" error (Section 6.5) when the
datagram arrives. All Traceroute needs to do is differentiate between
the received ICMP messages-time exceeded versus port unreachable-to know
when it's done.”
And here’s a link where you can read it online:
http://starlet.deltatel.ru/tcp_stivens/tracerou.htm#8_2
Crystal?
-- steve
-----Original Message-----
From: micky [mailto:micky@apol.com.tw]
Sent: Wednesday, November 28, 2001 7:05 PM
To: swm@emanon.com
Cc: cisco-nsp@puck.nether.net
Subject: Re: [nsp] Cisco ios traceroute VS. windows tracert ?
Hi Scott
Thanks for providing information
You said Cisco listening-UDP port number is 33434 for tracerouting
,but I can't scan the port with scan tools
Is it hidden port ?
Micky
----- Original Message -----
From: Scott Morris
To: 'micky' ; cisco-nsp@puck.nether.net
Sent: Wednesday, November 28, 2001 8:18 PM
Subject: RE: [nsp] Cisco ios traceroute VS. windows tracert ?
You have the right idea, just a little backwards!
Cisco IOS traceroute, like unix traceroute is a UDP-based system. It
sends out packets destined to a high UDP port (33434 by default).
Microsoft tracert on the other hand functions just like a ping. It
sends out ICMP echo packets incrementing the TTL in the same fashion.
So depending on access-lists on routers between you and your
destination, you may get very different results (and perhaps different
paths) depending on which box you run the trace from.
Hope that helps!
Scott
-----Original Message-----
From: micky [mailto:micky@apol.com.tw]
Sent: Wednesday, November 28, 2001 5:10 AM
To: cisco-nsp@puck.nether.net
Subject: [nsp] Cisco ios traceroute VS. windows tracert ?
Hi Mr.techs
I have a little confusing about traceroute function between cisco
ios and windows utility
Sometimes I used "tracert -d" x.x.x.x command under windows,it can
go through all nodes and display ip address of all
But using traceroute under IOS,it can goes through all and display
* * *
Somebody told me tracert is UDP-designed,traceroute is
ICMP-designed
I don't know if it's real or not ?
Thanks
Micky
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