Linux netstat in python

netstat.py

# -*- coding: utf-8 -*-
# ref 
# * https://gist.github.com/aleiphoenix/0e886336522c2f41412d
# * https://stackoverflow.com/questions/3319521/how-can-i-match-each-proc-net-tcp-entry-to-each-opened-socket
# * https://stackoverflow.com/questions/14667215/finding-a-process-id-given-a-socket-and-inode-in-python-3

# read /proc/net/tcp get address port and inode. get pid by checking every sysbol link to this inode in every /proc/<PID>/fd
import re
import os
import sys

with open('/proc/net/tcp') as f:
    lineno = 0
    sockets = []
    for line in f:
        lineno += 1
        if lineno == 1:
            continue

        sockets.append(line.strip())

columns = ("seq", "uid", "inode", "local", "remote", "timeout")
title = dict()
for c in columns:
    title[c] = c

def split_every_n(data, n):
    return [data[i:i+n] for i in range(0, len(data), n)]

def convert_linux_netaddr(address):

    hex_addr, hex_port = address.split(':')

    addr_list = split_every_n(hex_addr, 2)
    addr_list.reverse()

    addr = ".".join(map(lambda x: str(int(x, 16)), addr_list))
    port = str(int(hex_port, 16))

    return "{}:{}".format(addr, port)

def format_line(data):
    #print data
    return ("{seq:4s} {uid:5s} {local:25s} {remote:25s} " +
             "{timeout:8s} {inode:8s} \n".format(**data))
             
def find_pid(inode):

    # get a list of all files and directories in /proc
    procFiles = os.listdir("/proc/")

    # remove the pid of the current python process
    procFiles.remove(str(os.getpid()))

    # set up a list object to store valid pids
    pids = []

    for f in procFiles:
        try:
            # convert the filename to an integer and back, saving the result to a list
            integer = int(f)
            pids.append(str(integer))
        except ValueError:
            # if the filename doesn't convert to an integer, it's not a pid, and we don't care about it
            pass

    for pid in pids:
        # check the fd directory for socket information
        fds = os.listdir("/proc/%s/fd/" % pid)
        for fd in fds:
            # save the pid for sockets matching our inode
            if ('socket:[%s]' % inode) == os.readlink("/proc/%s/fd/%s" % (pid, fd)):
                return pid
                
rv = []
for info in sockets:
    _ = re.split(r'\s+', info)

    _tmp = {
        'seq': _[0],
        'local': convert_linux_netaddr(_[1]),
        'remote': convert_linux_netaddr(_[2]),
        'uid': _[7],
        'timeout': _[8],
        'inode': _[9],
        'pid': find_pid(_[9])
    }
    rv.append(_tmp)

if len(rv) > 0:
    title = "{:4s} {:5s} {:25s} {:25s} {:8s} {:8s} \n".format(*title)
    sys.stderr.write(title)

    for _ in rv:
        sys.stdout.write(str(_)+'\n')