Traceroute

[furzl]

Can anyone answer this please. I am using a windows based system.

If my ADSL router is connected to Telkom or to Mweb I am unable to traceroute.
If I connect into a VPN traceroute works fine.

In all three instances I can run a ping however so it is not an ICMP error.

Can any offer an explaination why a ping would work and a traceroute not. Is it possible to enable a traceroute

 

[Jah]

The ICMP packet size for a traceroute is larger than the packet size for a ping. I've seen some large networks set their routers to drop ICMP packets over a certain size, which will exclude traceroutes but not ping requests. Are you sure you are not running a hardware firewall on your router which is doing just that?
Try switching your router to bridged mode and connecting via a pppoe connection, this should bypass any hardware firewall, and see if the problem persists.

 

[Carlhead]

how far does the Tracert go?

can you paste results... just xxxx out any IP's you don't want us having.

 

[jabulani]

I have found similar symptoms when my Microcom ADSL modem's firewall is set on - temporarily disable it and I can do a traceroute. Do not know why pings work and traceroutes don't, but there it is!

 

[Carlhead]

I have found similar symptoms when my Microcom ADSL modem's firewall is set on - temporarily disable it and I can do a traceroute. Do not know why pings work and traceroutes don't, but there it is!

I think Jah is right, the firewall filters ICMP packet sizes to reduce the risk of ICMP floods (DOS attacks).