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Old 12-22-2002, 11:36 AM   #1
david0321
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Using Traceroute


i have been trying to use traceroute. When i type it in i get 1.*** to 30. ***. So I looked in iptables -L and it says that my icmp port is unreachable. Think that this is my problem but not sure how to fix it. It looks like the file iptables is a binary file so not sure how to edit it?

From what i know of iptables is that it is a set of rules to use for network activity.

How can I fix this or learn how to fix it.

Thanks
 
Old 12-22-2002, 05:47 PM   #2
rohang
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Do you have any firewalling enabled (either IP chains or IP tables)?

Have you tried disabling it temporarily to test wither traceroute works with it turned off?
 
Old 12-22-2002, 09:59 PM   #3
darkknight_9
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I have problem launching traceroute .. I have it instaled but the terminal reports it as a unrecognized command .. I'm running KDE .. any idea what I can do ?

Thanks ..


Oh .. another thing .. is there anyway I can view the computers on the LAN grouped by Workgroup .. something like the "Network Neighbourhood" thing on Windows ? And is there a way to see the machines by name and not by their IP address ?

Last edited by darkknight_9; 12-22-2002 at 10:05 PM.
 
Old 12-23-2002, 05:18 AM   #4
david0321
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darknight_9

traceroute is in /usr/sbin so it is not in your path to run it you need to do /usr/sbin/tracerroute
 
Old 12-23-2002, 05:24 AM   #5
david0321
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rohang
I have a new install of rh8.0. unless a fire wall was installed by default one is not installled. And if it is have no idea how to shut it off to test.

i dual boot with windows i can switch to window and run traceroute just fine thought it might be the router stoping it.
 
Old 12-23-2002, 04:27 PM   #6
SlickWilly
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Yah.. RH will install iptables in 'medium' mode by default.

Sounds like you've got yourself a script there.
You can disable it by :

1) at a prompt type setup
2) select Firewall Configuration
3) Select No Firewall
4) traceroute something

Once you've established that it's running you might want to look closer at your icmp settings. I'm not sure that the default iptables setup looks like, but I expect it'll be filtering icmps in, but contain settings for icmp originating from your side - letting them in.

Many scripts filter based on ip address aswell, common ones include the private ip subnets of

10.x.x.x
192.168.x.x

Now, you *shouldnt* be expecting incoming from those ip's because they *shouldn't* be routing across the internet. However, many cable companies for instance, use the 10.x subet for their cable modems (the actual modem) and if you block *everything* from 10.x addresses, and 192.168.x.x addresses then your cable modem won't talk to you.

So, unblock those, and ensure it still works, and then if you're paranoid, put back blocks for services you don't want.

Slick.
 
Old 12-23-2002, 08:31 PM   #7
david0321
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SlickWilly

Thanks for your reply.

I did as you suggested and turned off the firewall. Still get the 1.*** 2.*** and so on when i run traceroute? Bout to pull my hair out on this one. I did a iptables -L and there is a message that says the icmp port is unreachable. I got to figure that somewhere there is somthing blocking traceroute.

Guess i'll look for a iptables & ipchains howto and see if i can find any information about this. Any thing eles that i might try would be appreciated.

Thanks again
 
Old 12-24-2002, 12:20 PM   #8
SlickWilly
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Looks like you're using a configured script then.

If you do an iptables -L and it's showing filters then your firewall is still up.

You can try :

iptables -F INPUT
iptables -F OUTPUT
iptables -F FORWARD

which will flush your table rules. It won't flush any tables created which aren't standard tables though, but they'll be hanging off those above, so that should sort you out.

Reading about this is definately encouraged, and if you find where your iptables script is running, posting the script would also be useful.

Slick.
 
Old 12-25-2002, 08:02 AM   #9
david0321
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slick

i tried the iptables -F INPUt and that did not work. Sending what this looks like in the hope it may help. It seems that it should work but something is still blocking it or will not send a icmp packet.

[root@localhost david]# /usr/sbin/traceroute adams.net
traceroute to adams.net (216.138.0.16), 30 hops max, 38 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *

Then when i run iptables -L i get This is after the firewall has been shut down in setup.

[root@localhost david]# /sbin/iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
 
Old 12-25-2002, 05:09 PM   #10
david0321
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Well someone else told me to try traceroute -I. That works with the firewall on or off. The -I switch forces the use of icmp packets. Traceroute without the -I switch will use udp packets. Ping I think also uses icmp packets?

It works ok but not sure why. Need to do some reading to figure it out.

Anyone that knows what How to's to read or what area to look in let me know.

Thanks
 
  


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