82 lines
3.3 KiB
Python
Executable File
82 lines
3.3 KiB
Python
Executable File
#!/usr/bin/env python
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"""
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This utility will find the ip addresses of all hosts that have connected to
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this device via ssh, then validate they are still in the list of allowed prefixes,
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and if not kill the ssh session with a SIGHUP.
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"""
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import os
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import re
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import subprocess
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# Run utmpdump, capture and return its output
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def run_utmpdump(_utmpFilename):
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devnull = file("/dev/null", "w" )
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p = subprocess.Popen(args=["utmpdump", _utmpFilename], stdout=subprocess.PIPE, stderr=devnull)
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(stdout, stderr) = p.communicate()
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rc = p.returncode
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assert rc is not None # because p.communicate() should wait.
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out = (stdout or '') + (stderr or '')
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if rc:
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e = SystemCommandError("%r: error code %d" % (" ".join(argv), rc))
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e.error = rc
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e.output = out
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raise e
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return stdout
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# Run utmpdump and parse its output into a list of dicts and return that
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def get_utmp_data(utmpFileName=None):
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"""Reads the specified utmp file.
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Returns a list of dictionaries, one for each utmp entry.
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All dictionary keys and values are strings
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Values are right padded with spaces and may contain all
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spaces if that utmp field is empty.
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Dictionary keys:
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"type": See UTMP_TYPE_* above
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"pid": Process ID as a string
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"tty": TTY (line) name - device name of tty w/o "/dev/"
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"tty4": 4 char abbreivated TTY (line) name
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"user": User ID
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"host": Hostname for remote login,
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kernel release for Run Level and Boot Time
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"ipAddr": IP Address
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"time": Time and date entry was made
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See linux docs on utmp and utmpdemp for more info.
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Example output from utmpdump:
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pid tty4 user tty host ipAddr time
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[7] [22953] [/238] [myname ] [pts/238 ] [example.com] [253.122.98.159 ] [Mon Dec 18 21:08:09 2017 PST]
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"""
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if not utmpFileName:
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utmpFileName = os.environ.get( "DEFAULT_UTMP_FILE", "/var/run/utmp" )
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if not os.path.exists(utmpFileName):
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return []
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output = run_utmpdump(utmpFileName)
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lines = re.split("\n", output)
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regExp = re.compile(
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r"\[(?P<type>" r"[^\]]*?)\s*\] \[(?P<pid>" r"[^\]]*?)\s*\] " \
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r"\[(?P<tty4>" r"[^\]]*?)\s*\] \[(?P<user>" r"[^\]]*?)\s*\] " \
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r"\[(?P<tty>" r"[^\]]*?)\s*\] \[(?P<host>" r"[^\]]*?)\s*\] " \
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r"\[(?P<ipAddr>" r"[^\]]*?)\s*\] \[(?P<time>" r"[^\]]*?)\s*\]" )
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entries = []
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for line in lines:
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m = regExp.match(line)
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if not m:
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# Skip header and any other lines we don't recognize
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continue
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entry = m.groupdict()
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entries.append(entry)
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return entries
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# Find the source ip addresses of all ssh sessions, verify they are still allowed, and if not kill the ssh session
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if __name__ == '__main__':
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for e in get_utmp_data():
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if e["host"] and e["ipAddr"] != "0.0.0.0": # entry is for a live connection
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# check allowness
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r = os.system('tcpdmatch sshd %s | grep "access.*granted" > /dev/null' % e["ipAddr"])
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# print some debugs
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print "From:", e["ipAddr"], "ssh pid:", e["pid"], "allowed" if r == 0 else "denied"
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# if needed go for the kill
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if r != 0:
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os.system("kill -1 %s" % e["pid"])
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