Imagine you run a Web service and want to determine the network-layer round trip time to clients that connect to your Web service. An ICMP ping is unlikely to work as most home routers don't respond to ICMP echo requests. A TCP ping is also unlikely to work because home routers typically don't respond to unexpected segments with a TCP RST segment. It is generally difficult to get home routers to respond to unsolicited traffic.
The key insight of the 0trace technique is to piggyback onto an already-established TCP connection to conduct a traceroute measurement. As long as the client has an open TCP connection to our Web service, we can inject segments with increasing TTL into the TCP connection. Firewalls along the path are more likely to respond to packets with an exceeded TTL if they are part of an established TCP connection. While this technique may not always make it all the way to the client, it tends to get close.
This Go package implements the 0trace traceroute technique.
The API is straightforward:
Instantiate a new ZeroTrace object by calling NewZeroTrace.
Then, start the object by invoking its Start method.
Afterwards, you can invoke the CalcRTT method
by providing the net.Conn object of an already-established TCP connection.
CalcRTT returns the round trip time to the client
(or the hop that's closest) as time.Duration, or an error.
ZeroTrace's
constructor
expects a configuration object as argument. Take a look at the
Config
struct to learn more about configuration options. The function
NewDefaultConfig
returns a default configuration object with reasonable defaults.
Use the code in the example directory to get started.
To test and lint the code, run:
make