2ping 3.0.0 has been released. It is a total rewrite, with the following features:

  • Total rewrite from Perl to Python.
  • Multiple hostnames/addresses may be specified in client mode, and will be pinged in parallel.
  • Improved IPv6 support:
    • In most cases, specifying -4 or -6 is unnecessary. You should be able to specify IPv4 and/or IPv6 addresses and it will “just work”.
    • IPv6 addresses may be specified without needing to add -6.
    • If a hostname is given in client mode and the hostname provides both AAAA and A records, the AAAA record will be chosen. This can be forced to one or another with -4 or -6.
    • If a hostname is given in listener mode with -I, it will be resolved to addresses to bind as. If the hostname provides both AAAA and A records, they will both be bound. Again, -4 or -6 can be used to restrict the bind.
    • IPv6 scope IDs (e.g. fe80::213:3bff:fe0e:8c08%eth0) may be used as bind addresses or destinations.
  • Better Windows compatibility.
  • ping(8)-compatible superuser restrictions (e.g. flood ping) have been removed, as 2ping is a scripted program using unprivileged sockets, and restrictions would be trivial to bypass. Also, the concept of a “superuser” is rather muddied these days.
  • Better timing support, preferring high-resolution monotonic clocks whenever possible instead of gettimeofday(). On Windows and OS X, monotonic clocks should always be available. On other Unix platforms, monotonic clocks should be available when using Python 2.7
  • Long option names for ping(8)-compatible options (e.g. adaptive mode can be called as –adaptive in addition to -A). See 2ping --help for a full option list.

Because of the IPv6 improvements, there is a small breaking functionality change. Previously, to listen on both IPv4 and IPv6 addresses, you needed to specify -6, e.g. 2ping --listen -6 -I -I ::1. Now that -6 restricts binds to IPv6 addresses, that invocation will just listen on ::1. Simply remove -6 to listen on both IPv4 and IPv6 addresses.

This is a total rewrite in Python, and the original Perl code was not used as a basis, instead writing the new version from the 2ping protocol specification. (The original Perl version was a bit of a mess, and I didn’t want to pick up any of its habits.) As a result of rewriting from the specification, I discovered the Perl version’s implementation of the checksum algorithm was not even close to the specification (and when it comes to checksums, “almost” is the same as “not even close”). As the Perl version is the only known 2ping implementation in the wild which computes/verifies checksums, I made a decision to amend the specification with the “incorrect” algorithm described in pseudocode. The Python version’s checksum algorithm matches this in order to maintain backwards compatibility.

This release also marks the five year anniversary of 2ping 1.0, which was released on October 20, 2010.