Traceroute in Go

A traceroute library written in Go.

Features:

• blocking and non blocking mode
• structured output, in text or JSON
• configurable options like: resolve domain names, startTTL, payloadSize, timeouts, retries
• works correctly when launching in multiple concurrent processes and doesn't catch ICMP replies from other processes, like most of similar utilities do.

Syscalls and RAW_SOCKETS are used to perform network operations, so root privileges is required to execute the command or you can use sudo, or set the SET_CAP_RAW flag on the executable file using the setcap command: setcap cap_net_raw+ep /path_to_exec_file

This library uses BPF (Berkley packet filter) connected to the socket in order to filter received RAW network packets at the kernel side. BPF isn't supported on Windows and is not tested on Mac. I have no test environment to check this cases now. BPF can be disabled on Windows/Mac with the loss of the opportunity to work in a competitive mode.

Only 1024 concurrent 'traceroutes' at the same time is supported. More concurrent traceroutes is allowed, but it leads to some packets would be lost.

CLI App

go build cmd/gotraceroute
sudo ./gotraceroute example.com

Library

See traceroute_test.go for an example of how to use the library from within your application.

The gotraceroute.Run() function accepts a domain name and an options struct and immediately returns with a channel where a Hop data struct should be reading from. When traceroute is finished, the channel will be closed.

The gotraceroute.RunBlock() function accepts a domain name and an options struct, perform a traceroute and returns an array of Hop structs with traceroute result.

Resources

Useful resources:

• http://en.wikipedia.org/wiki/Traceroute
• http://tools.ietf.org/html/rfc792
• http://en.wikipedia.org/wiki/Internet_Control_Message_Protocol

Notes

• https://code.google.com/p/go/source/browse/src/pkg/net/ipraw_test.go
• http://godoc.org/code.google.com/p/go.net/ipv4
• http://golang.org/pkg/syscall/

Thanks

Based on traceroute implementation https://github.com/aeden/traceroute which was fully reworked and as a result several annoying bugs was fixed, error handling was added, and it was adopted to concurrent execution.

Some ideas about packet construction and decoding also was get from https://github.com/Syncbak-Git/traceroute

How to apply BPF to a raw socket in golang, thanks to: https://riyazali.net/posts/berkeley-packet-filter-in-golang/