run in background (daemon) and option

client.py

@@ -4,6 +4,7 @@ import helpers, ssnet, ssh
 from ssnet import SockWrapper, Handler, Proxy, Mux, MuxWrapper
 from helpers import *
 
+import os, sys, atexit, signal, syslog
 
 def original_dst(sock):
     try:
@@ -97,14 +98,40 @@ class FirewallClient:
         if rv:
             raise Fatal('cleanup: %r returned %d' % (self.argv, rv))
 
+def exit_cleanup():
+    debug1('exit cleanup\n')
+    os.unlink('sshuttle.pid')
 
-def _main(listener, fw, ssh_cmd, remotename, python, seed_hosts, auto_nets):
+def _main(listener, fw, ssh_cmd, remotename, python, seed_hosts, auto_nets, background):
     handlers = []
     if helpers.verbose >= 1:
         helpers.logprefix = 'c : '
     else:
         helpers.logprefix = 'client: '
     debug1('connecting to server...\n')
+
+    if background:
+        helpers.do_syslog = True
+        syslog.openlog('sshuttle')
+
+        # we're redirecting the standard outputs here early so that
+        # the stderr debug message of ssh subprocess would be
+        # redirected properly 
+
+        # TODO: redirecting stderr of ssh to syslog
+
+        sys.stdout.flush()
+        sys.stderr.flush()
+        si = file('/dev/null', 'r')
+        so = file('/dev/null', 'a+')
+        se = file('/dev/null', 'a+', 0)
+        os.dup2(si.fileno(), sys.stdin.fileno())
+        os.dup2(so.fileno(), sys.stdout.fileno())
+        os.dup2(se.fileno(), sys.stderr.fileno())
+        si.close()
+        so.close()
+        se.close()
+
     try:
         (serverproc, serversock) = ssh.connect(ssh_cmd, remotename, python)
     except socket.error, e:
@@ -126,6 +153,22 @@ def _main(listener, fw, ssh_cmd, remotename, python, seed_hosts, auto_nets):
         raise Fatal('expected server init string %r; got %r'
                         % (expected, initstring))
     debug1('connected.\n')
+    if background:
+        debug1('daemonizing\n')
+        if os.fork(): 
+            os._exit(0)
+        os.setsid() 
+        if os.fork(): 
+            os._exit(0)
+
+        outfd = os.open('sshuttle.pid', 
+                        os.O_WRONLY | os.O_CREAT | os.O_EXCL)
+        os.write(outfd, '%i' % os.getpid())
+        os.close(outfd)
+
+        atexit.register(exit_cleanup)
+        # Normal exit when killed, or atexit won't work
+        signal.signal(signal.SIGTERM, lambda signum, stack_frame: sys.exit(1))
 
     def onroutes(routestr):
         if auto_nets:
@@ -182,7 +225,7 @@ def _main(listener, fw, ssh_cmd, remotename, python, seed_hosts, auto_nets):
 
 
 def main(listenip, ssh_cmd, remotename, python, seed_hosts, auto_nets,
-         subnets_include, subnets_exclude):
+         subnets_include, subnets_exclude, background):
     debug1('Starting sshuttle proxy.\n')
     listener = socket.socket()
     listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -213,6 +256,6 @@ def main(listenip, ssh_cmd, remotename, python, seed_hosts, auto_nets,
     
     try:
         return _main(listener, fw, ssh_cmd, remotename,
-                     python, seed_hosts, auto_nets)
+                     python, seed_hosts, auto_nets, background)
     finally:
         fw.done()

helpers.py

@@ -1,10 +1,14 @@
-import sys, os
+import sys, os, syslog
 
 logprefix = ''
 verbose = 0
+do_syslog = False
 
 def log(s):
     try:
+        if do_syslog:
+            syslog.syslog(logprefix + s)
+        else:
             sys.stdout.flush()
             sys.stderr.write(logprefix + s)
             sys.stderr.flush()

main.py

@@ -45,10 +45,11 @@ def parse_ipport(s):
 
 
 optspec = """
-sshuttle [-l [ip:]port] [-r [username@]sshserver[:port]] <subnets...>
+sshuttle [-b] [-l [ip:]port] [-r [username@]sshserver[:port]] <subnets...>
 sshuttle --firewall <port> <subnets...>
 sshuttle --server
 --
+b,background run in background as daemon
 l,listen=  transproxy to this ip address and port number [0.0.0.0:0]
 H,auto-hosts scan for remote hostnames and update local /etc/hosts
 N,auto-nets  automatically determine subnets to route
@@ -104,7 +105,8 @@ try:
                              sh,
                              opt.auto_nets,
                              parse_subnets(includes),
-                             parse_subnets(excludes)))
+                             parse_subnets(excludes),
+                             opt.background))
 except Fatal, e:
     log('fatal: %s\n' % e)
     sys.exit(99)