Using Ipv4RawSocket to change IpTtl doesn't work?

[NanerLee]

Hello,everyone!

      Today, I want to write a n3 traceroute application. I create a icmp echo packet and use the Ipv4RawSocket (ttl =1) to sending it to a node. Once one packet is sent, I will  ++ttl. But when I run the program ,the socket send a packet with ttl =64 (should be 1).

      I think that my codes maybe have some errors, so I find the v4ping.cc and add a line code (m_socket -> SetIpTtl(2)) before socket sent packet.

then I use v4ping application and find that v4ping also sent a echo packet with ttl =64.

      so, I guess there are some problem in Ipv4RawSocket. What's more, UdpSocket and TcpSocket are ok. And I also change the Ipv4 protocol to make it can reply the icmp.

      

   Is there someone have some advice? Thanks.

[Tommaso Pecorella]

Hi,

it's a bug. Can you provide a test script ?

Thanks,

T.

[Tommaso Pecorella]

The patch in bug 2500 should fix your problem.

Nevertheless, a test case would be very helpful.

Thanks,

T.

[NanerLee]

Thanks ! 

Yesterday I also saw source codes and compared Ipv4RawSocket with UdpSocket. I found the IpRawSocket didn't check IsManualIpTtl  and handle the  SocketIpTtlTag and so on.

Now, I see your patch, and I think it should fix the bug. But I'm not at my computer. So I will test it tomorrow. When I complete the test, I will reply you again.

Thanks again !    

[NanerLee]

Hello, Tommaso Pecorella !

        Today, I download your patch. I find your version is ns3-dev, but I use ns-3.25 now. InetSocketAddress is different between them. So I just test the part of ttl, and it's ok.  Thanks again!

在 2016年9月10日星期六 UTC+8下午10:27:38，Tommaso Pecorella写道：

[Tommaso Pecorella]

Hi,

the patch has been pushed and it's "live" in ns-3-dev (it will be incorporated in 3.26).

Thanks for finding this.

Cheers,

T.