Mike Schilli
and 1 contributors


SVN::Utils::ClientIP - Get the client's IP address in a Subversion Hook


    use SVN::Utils::ClientIP qw(ssh_client_ip);

    print "The client's IP address is ", ssh_client_ip();


SVN::Utils::ClientIP solves the age-old problem of obtaining the SSH client's IP address in a commit hook of a Subversion repository.

Knowing the client's IP address can be quite useful in heavily used Subversion installations, as it allows for maintaining a log on who accessed a repository when and from where.

However, the Subversion developers are not very accomodating when it comes to this, claiming "security purposes":


But, if you think about how a client connects to the repository using SSH, which then spawns the svn process, it becomes quite clear how you can get the IP address, even if the Subversion folks are hiding it from you: Starting from the currently running hook, walk up the process hierarchy, until you reach the parent that's the SSH instance serving the client (only tested with openssh). In its environment, you'll find a variable named SSH_CLIENT, which contains the IP address of the connecting client.

This is exactly what this module does, and you can simply obtain the SSH client's IP address by running

    use SVN::Utils::ClientIP qw(ssh_client_ip);

    my $ip = ssh_client_ip();

Under the hood, the module uses the CPAN modules Proc::ProcessTable for obtaining the ppid() to walk up the process hierarchy and Proc::Info::Environment for reading out the SSH_CLIENT environment variable. By the time of this writing, the latter only worked for Linux, but in the meantime other OSes might be supported.

It's not terribly expensive, but it adds up and if you're using the function many times, you might want to memoize() it.


The ssh_client_ip() convenience function illustrated above will suffice for most hooks, if you want more control or diagnosing functions, use the full object notation:

    use SVN::Utils::ClientIP;

    my $finder = SVN::Utils::ClientIP->new();

    if( my $ip = $finder->ssh_client_ip_find() ) {
        print "Found IP address: $ip\n";
    } else {
        print "IP address not found: ", $finder->error(), "\n";

The SSH_CLIENT variable of the ssh process contains not only the client's IP address, but also the pid of the process and the port the client docked on to (typically 22). It looks something like this:

    " 57890 22"

The convenience function ssh_client_ip returns only the first part. If you call the object method in scalar context, it also returns only the IP address and skips the two following fields. If you want all fields, use ssh_client_ip_find() in list context:

    my($ip, $pid, $port) = $finder->ssh_client_ip_find();

and $pid and $port will be populated with the values found after separating blanks in SSH_CLIENT.


Copyright 2010 by Mike Schilli, all rights reserved. This program is free software, you can redistribute it and/or modify it under the same terms as Perl itself.


2010, Mike Schilli <cpan@perlmeister.com>