call IPtables command within python script -

i trying call following command in python script. trying insert rule ip tables. using sub process call , inserting variables needed, getting large error. suggestions?

iptables = subprocess.call('iptables -i forward -eth 0 -m '+protocol+' -t'+protocol+'--dport '+port+'-j dnat --to-destination'+ipaddress) 

error:

traceback (most recent call last):   file "./port_forward.py", line 42, in <module>     iptables = subprocess.call('iptables -i forward -i eth0 -m '+protocol+' -t'+protocol+'--dport '+port+'-j dnat --to-destination'+ipaddress)   file "/usr/lib/python2.7/subprocess.py", line 493, in call     return popen(*popenargs, **kwargs).wait()   file "/usr/lib/python2.7/subprocess.py", line 679, in __init__     errread, errwrite)   file "/usr/lib/python2.7/subprocess.py", line 1259, in _execute_child     raise child_exception oserror: [errno 2] no such file or directory 

your problem common python beginners. instead of formatting string command, trying build complex string concatenating many strings , variables. instead, use string format, allow test command , make code more readable , flexible.

your original string lacks spaces between options , arguments, e.g. --to-destination1.2.3.4.

hence, you should format string (this works python 2.7):

opts = {'iptables': '/sbin/iptables', 'protocol': 'tcp', 'port': 80, 'ipaddress': '0.0.0.0'} ipcmd = '{iptables} -i forward -eth 0 -m {protocol} -t {protocol} \ --dport {port} -j dnat --to-destination  {ipaddress}'.format(**opts)  if debug:    print ipcmd iptables = subprocess.call(ipcmd) 

this easier modify later, , also, when more python programming, see more readable.

also, call iptables, should root, stated in comments: in beginning of script add:

   import sys    import os    if not os.getuid() == 0:         print "you must root change iptables."         sys.exit(2) 

update after seeing error trace:

you trying call command iptables not in path. should call full path of iptables , e.g. /sbin/iptables