tracert

[Chrissirhc]

Can you specify ports with tracert?

 

[TheOldMan346]

Not sure what you mean. Tracert is :
======
Determines the path taken to a destination by sending Internet Control Message Protocol (ICMP) Echo Request messages to the destination with incrementally increasing Time to Live (TTL) field values. The path displayed is the list of near-side router interfaces of the routers in the path between a source host and a destination. The near-side interface is the interface of the router that is closest to the sending host in the path.
======

The ICMP protocol is on a specified port. Do you mean using a port other than the designated ICMP port? Or do you have something else in mind?

What goes around - comes around.
The Old Man

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[HMeyer]

ICMP have no assign port, it works on layer 3.....

Use the traceroute tool from Linux System, that works with UDP . The default destination port is 33434. You can change this port... You find more information in the manuels... "man traceroute" on the system.

Regards
Helge

 

[Chrissirhc]

I was talking about changing the port that it works on.

Helge does that mean TheOldMan is right with dos as it uses icmp packets. And if I want to do a tracert on a desination port xxxx I must use linux traceroute tool?

Thanks

Chris

 

[TheOldMan346]

Chrissirhc,

What are you trying to accomplish?

Tracert traces the route packets take from point A to point B regardless of the port. It would be the same for port 80 as it would be for port 12345. I may be missing something but how would specifying a port make a difference? Perhaps you could use a different tool depending on what you need to do.
What goes around - comes around.
The Old Man

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[Chrissirhc]

I'm thinking about firewalls. But I guess as long as they accept icmp packets it will allow traceroute to a destination. I did however think that any kind of connection on the internet I need to go via a port. Say all ports except port 20 on destination were closed I would still be able to do a traceroute to that destination right?

 

[jimbopalmer]

most 'home' routers default to not allow a icmp ping on the WAN port, which DOES stop trace route, but makes the home device less prone to attack. I tried to remain child-like, all I acheived was childish.

 

[TheOldMan346]

Chrissirhc,

As HMeyer mentioned, ICMP is at the foundation of the protocol stack along with TCP and UDP and the concept of port number does not apply to ICMP. Basically ICMP is an error reporting and control protocol.

This is what the tracert does:
===============
The TRACERT diagnostic utility determines the route taken to a destination by sending Internet Control Message Protocol (ICMP) echo packets with varying IP Time-To-Live (TTL) values to the destination. Each router along the path is required to decrement the TTL on a packet by at least 1 before forwarding it, so the TTL is effectively a hop count. When the TTL on a packet reaches 0, the router should send an ICMP Time Exceeded message back to the source computer.

TRACERT determines the route by sending the first echo packet with a TTL of 1 and incrementing the TTL by 1 on each subsequent transmission until the target responds or the maximum TTL is reached. The route is determined by examining the ICMP Time Exceeded messages sent back by intermediate routers. Note that some routers silently drop packets with expired TTLs and are invisible to TRACERT.
===============

So, basically, you don't need any ports open to do a tracert. The ICMP packets are part of the whole OSI infrastructure.

Hope that helps.
What goes around - comes around.
The Old Man

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[pansophic]

Try using hping2. It is a *nix utility that allows you to do TCP/UDP/ICMP/RAW-IP pings, specifying the source and destination ports, etc.

You can ping through a firewall quite simply with this.

http://www.hing.org

pansophic
pansophic

 

[Chrissirhc]

Okay. Ping uses ICMP packets as well. So I guess it is not dependent on port either?