This script will patch a minecraft_server.jar to have a connection-throttle of zero. This is useful to folks running behind proxies. It requires python 2.7 and the java runtime environment (specifically the `jar` binary)

throttlepatch.py

from os import chdir, path
from tempfile import mkdtemp
from shutil import rmtree
from struct import pack
from subprocess import check_output

def jar_contents(j_path):
    return check_output(['jar', 'tf', j_path]).split("\n")

def jar_extract(j_path):
    return check_output(['jar', 'xf', j_path])

def jar_update(j_path, t_path, c_path):
    c_path = c_path[len(t_path)+1:]
    return check_output(['jar', 'uf', j_path, '-C', t_path, c_path])

def jlong(v):
    return pack('>q', v)

def jstring(v):
    return pack('>h', len(v)) + v

def main(j_path, t_path):
    print "... checking jar"
    j_path = path.realpath(j_path)
    if not path.isfile(j_path):
        print "### not found: %s" % j_path
        return

    print "... getting jar contents"
    j_contents = jar_contents(j_path)

    print "... extracting jar"
    chdir(t_path)
    jar_extract(j_path)

    print "... searching for DedicatedServerConnectionThread"
    search = jstring('Listen thread')
    replace = (jlong(4000), jlong(0))
    c_path = None
    c_data = None
    for name in j_contents:
        name = "%s/%s" % (t_path, name)
        if not name.endswith('.class'):
            continue

        with open(name, 'rb') as f:
            data = f.read()

        if search in data:
            c_path = name
            c_data = data
            break

    if c_path is None:
        print "### couldn't find class!"
        return

    print "... patching"
    if not replace[0] in c_data:
        print "### already patched!"
        return

    c_data = c_data.replace(*replace)

    print "... saving"
    with open(c_path, 'wb') as f:
        f.write(c_data)

    jar_update(j_path, t_path, c_path)

    print  "... done!"

if __name__ == '__main__':
    import sys
    if len(sys.argv) != 2:
        print "usage: python throttlepath.py jar_path"
    else:
        t_path = mkdtemp(prefix='throttle-patch-')
        main(sys.argv[1], t_path)
        rmtree(t_path)