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#!/usr/bin/python
"""
This program is intended to be run via sudo, and does the following
things:
1. Sets up a high-performance networking environment by tweaking
various sysctl settings.
2. Runs either an interactive shell or a command line program.
3. Resets the environment back to what it was.
"""
import os
import sys
import tempfile
SYSCTLS = dict(
Darwin={
'kern.ipc.somaxconn': 1024,
'kern.maxfiles': 22528,
'kern.maxfilesperproc': 20480,
'net.inet.ip.portrange.first': 1024,
'net.inet.ip.portrange.hifirst': 1024,
},
Linux={
'net.core.somaxconn': 1024,
'net.core.rmem_max': 16777216,
'net.core.wmem_max': 16777216,
'net.ipv4.ip_local_port_range': '1024 65535',
'net.ipv4.tcp_fin_timeout': 15,
'net.ipv4.tcp_max_syn_backlog': 16384,
'net.ipv4.tcp_rmem': '4096 87380 16777216',
'net.ipv4.tcp_tw_recycle': 1,
'net.ipv4.tcp_tw_reuse': 1,
'net.ipv4.tcp_wmem': '4096 65536 16777216',
},
)
ULIMITS = dict(
Darwin={
'-n': 20480,
},
Linux={
'-n': 131072,
},
)
if os.access('/sbin/sysctl', os.X_OK):
SYSCTL = '/sbin/sysctl'
elif os.access('/usr/sbin/sysctl', os.X_OK):
SYSCTL = '/usr/sbin/sysctl'
else:
print >> sys.stderr, 'where is sysctl!?'
sys.exit(1)
CHANGED_SYSCTLS = {}
def change_sysctl(name, newval):
""" Set kernel parameters using sysctl for the appropriate platform """
oldval = os.popen('%s -n %s' % (SYSCTL, name), 'r').read().strip().replace('\t', ' ')
if not oldval:
print('could not get value of ' + name, file=sys.stderr)
return
if oldval == str(newval):
return
ret = os.system('%s -w %s=%r 2>/dev/null' % (SYSCTL, name, newval))
if ret != 0:
print('could not change %s from %s to %r' % (name, oldval, newval),
file=sys.stderr)
return
CHANGED_SYSCTLS[name] = oldval
PLATFORM = os.uname()[0]
for (n, v) in SYSCTLS[PLATFORM].items():
change_sysctl(n, v)
FD, PATH = tempfile.mkstemp('.sh')
FP = os.fdopen(FD, 'w')
for (n, v) in ULIMITS[PLATFORM].items():
print('ulimit %s %s' % (n, v), file=FP)
if len(sys.argv) > 1:
print('exec ' + ' '.join(sys.argv[1:]), file=FP)
else:
print('exec %s -l' % os.environ.get('SHELL', '/bin/bash'), file=FP)
FP.close()
os.system('exec /bin/sh ' + PATH)
os.unlink(PATH)
for (n, v) in CHANGED_SYSCTLS.items():
change_sysctl(n, v)
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