Python scanner for the first free port in a range
$begingroup$
I have a distributed application (YARN), which runs a WebApp.
This application use a default port to start (8008), before I start I need to check if port is in use.
A container may run in the same virtual machine, hence port may be in use.
(Max I have 4 containers in WebApp).
I created the following code which seem to work, but want to see if there are some clean ups/improvements suggested.
def port_in_use(port):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1', port))
if result == 0:
return True
else:
return False
def start_dashboard():
base_port = os.getenv('DASHBOARD_PORT_ENV_VAR', 8008)
scan_ports = True
attempts = 0
max_attempts = 10
while(scan_ports and attempts <= max_attempts):
if port_in_use(base_port):
base_port += 1
attempts += 1
else:
scan_ports = False
if attempts == max_attempts:
raise IOError('Port in use')
dashboard.configure(port=base_port)
dashboard.launch()
python python-3.x networking socket
edited 2 days ago
200_success
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
$endgroup$
add a comment |
$begingroup$
I have a distributed application (YARN), which runs a WebApp.
This application use a default port to start (8008), before I start I need to check if port is in use.
A container may run in the same virtual machine, hence port may be in use.
(Max I have 4 containers in WebApp).
I created the following code which seem to work, but want to see if there are some clean ups/improvements suggested.
def port_in_use(port):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1', port))
if result == 0:
return True
else:
return False
def start_dashboard():
base_port = os.getenv('DASHBOARD_PORT_ENV_VAR', 8008)
scan_ports = True
attempts = 0
max_attempts = 10
while(scan_ports and attempts <= max_attempts):
if port_in_use(base_port):
base_port += 1
attempts += 1
else:
scan_ports = False
if attempts == max_attempts:
raise IOError('Port in use')
dashboard.configure(port=base_port)
dashboard.launch()
python python-3.x networking socket
edited 2 days ago
200_success
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
$endgroup$
add a comment |
$begingroup$
I have a distributed application (YARN), which runs a WebApp.
This application use a default port to start (8008), before I start I need to check if port is in use.
A container may run in the same virtual machine, hence port may be in use.
(Max I have 4 containers in WebApp).
I created the following code which seem to work, but want to see if there are some clean ups/improvements suggested.
def port_in_use(port):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1', port))
if result == 0:
return True
else:
return False
def start_dashboard():
base_port = os.getenv('DASHBOARD_PORT_ENV_VAR', 8008)
scan_ports = True
attempts = 0
max_attempts = 10
while(scan_ports and attempts <= max_attempts):
if port_in_use(base_port):
base_port += 1
attempts += 1
else:
scan_ports = False
if attempts == max_attempts:
raise IOError('Port in use')
dashboard.configure(port=base_port)
dashboard.launch()
python python-3.x networking socket
edited 2 days ago
200_success
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
$endgroup$
I have a distributed application (YARN), which runs a WebApp.
This application use a default port to start (8008), before I start I need to check if port is in use.
A container may run in the same virtual machine, hence port may be in use.
(Max I have 4 containers in WebApp).
I created the following code which seem to work, but want to see if there are some clean ups/improvements suggested.
def port_in_use(port):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1', port))
if result == 0:
return True
else:
return False
def start_dashboard():
base_port = os.getenv('DASHBOARD_PORT_ENV_VAR', 8008)
scan_ports = True
attempts = 0
max_attempts = 10
while(scan_ports and attempts <= max_attempts):
if port_in_use(base_port):
base_port += 1
attempts += 1
else:
scan_ports = False
if attempts == max_attempts:
raise IOError('Port in use')
dashboard.configure(port=base_port)
dashboard.launch()
python python-3.x networking socket
python python-3.x networking socket
edited 2 days ago
200_success
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
edited 2 days ago
200_success
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
edited 2 days ago
200_success
130k17155419
edited 2 days ago
200_success
130k17155419
edited 2 days ago
200_success
130k17155419
130k17155419
asked 2 days ago
spicyramenspicyramen
307312
asked 2 days ago
spicyramenspicyramen
307312
asked 2 days ago
spicyramenspicyramen
307312
307312
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Your code has some incorrect assumptions.
an application may listen on a specific address/port combination;
127.0.0.1:portcan be available while*:portis not.an application may bind a port without listening. Connects will fail, but so will your own bind.
a firewall or other mechanism can interfere with connections, generating false positives in your scan.
The reliable approach is to bind the port, just as your dashboard will, and then release it.
result = sock.bind(('', port))
sock.close()
You'll need to catch the exception and this is a good opportunity to move the whole thing into a function. That will make the start_dashboard logic cleaner and get rid of boolean loop-terminator scan_ports. Just exit the loop by returning the answer.
def next_free_port( port=1024, max_port=65535 ):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while port <= max_port:
try:
sock.bind(('', port))
sock.close()
return port
except OSError:
port += 1
raise IOError('no free ports')
def start_dashboard():
# pass optional second parameter "max_port" here, else scan until a free one is found
port = next_free_port( os.getenv('DASHBOARD_PORT_ENV_VAR', 8008) )
dashboard.configure(port=port)
dashboard.launch()
You can use netcat to make ports in-use for testing: nc -l -p 9999 will listen on port 9999; press control-C to end it.
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
$endgroup$
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
|
show 1 more comment
Your Answer
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Your code has some incorrect assumptions.
an application may listen on a specific address/port combination;
127.0.0.1:portcan be available while*:portis not.an application may bind a port without listening. Connects will fail, but so will your own bind.
a firewall or other mechanism can interfere with connections, generating false positives in your scan.
The reliable approach is to bind the port, just as your dashboard will, and then release it.
result = sock.bind(('', port))
sock.close()
You'll need to catch the exception and this is a good opportunity to move the whole thing into a function. That will make the start_dashboard logic cleaner and get rid of boolean loop-terminator scan_ports. Just exit the loop by returning the answer.
def next_free_port( port=1024, max_port=65535 ):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while port <= max_port:
try:
sock.bind(('', port))
sock.close()
return port
except OSError:
port += 1
raise IOError('no free ports')
def start_dashboard():
# pass optional second parameter "max_port" here, else scan until a free one is found
port = next_free_port( os.getenv('DASHBOARD_PORT_ENV_VAR', 8008) )
dashboard.configure(port=port)
dashboard.launch()
You can use netcat to make ports in-use for testing: nc -l -p 9999 will listen on port 9999; press control-C to end it.
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
$endgroup$
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
|
show 1 more comment
$begingroup$
Your code has some incorrect assumptions.
an application may listen on a specific address/port combination;
127.0.0.1:portcan be available while*:portis not.an application may bind a port without listening. Connects will fail, but so will your own bind.
a firewall or other mechanism can interfere with connections, generating false positives in your scan.
The reliable approach is to bind the port, just as your dashboard will, and then release it.
result = sock.bind(('', port))
sock.close()
You'll need to catch the exception and this is a good opportunity to move the whole thing into a function. That will make the start_dashboard logic cleaner and get rid of boolean loop-terminator scan_ports. Just exit the loop by returning the answer.
def next_free_port( port=1024, max_port=65535 ):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while port <= max_port:
try:
sock.bind(('', port))
sock.close()
return port
except OSError:
port += 1
raise IOError('no free ports')
def start_dashboard():
# pass optional second parameter "max_port" here, else scan until a free one is found
port = next_free_port( os.getenv('DASHBOARD_PORT_ENV_VAR', 8008) )
dashboard.configure(port=port)
dashboard.launch()
You can use netcat to make ports in-use for testing: nc -l -p 9999 will listen on port 9999; press control-C to end it.
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
$endgroup$
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
|
show 1 more comment
$begingroup$
Your code has some incorrect assumptions.
an application may listen on a specific address/port combination;
127.0.0.1:portcan be available while*:portis not.an application may bind a port without listening. Connects will fail, but so will your own bind.
a firewall or other mechanism can interfere with connections, generating false positives in your scan.
The reliable approach is to bind the port, just as your dashboard will, and then release it.
result = sock.bind(('', port))
sock.close()
You'll need to catch the exception and this is a good opportunity to move the whole thing into a function. That will make the start_dashboard logic cleaner and get rid of boolean loop-terminator scan_ports. Just exit the loop by returning the answer.
def next_free_port( port=1024, max_port=65535 ):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while port <= max_port:
try:
sock.bind(('', port))
sock.close()
return port
except OSError:
port += 1
raise IOError('no free ports')
def start_dashboard():
# pass optional second parameter "max_port" here, else scan until a free one is found
port = next_free_port( os.getenv('DASHBOARD_PORT_ENV_VAR', 8008) )
dashboard.configure(port=port)
dashboard.launch()
You can use netcat to make ports in-use for testing: nc -l -p 9999 will listen on port 9999; press control-C to end it.
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
$endgroup$
Your code has some incorrect assumptions.
an application may listen on a specific address/port combination;
127.0.0.1:portcan be available while*:portis not.an application may bind a port without listening. Connects will fail, but so will your own bind.
a firewall or other mechanism can interfere with connections, generating false positives in your scan.
The reliable approach is to bind the port, just as your dashboard will, and then release it.
result = sock.bind(('', port))
sock.close()
You'll need to catch the exception and this is a good opportunity to move the whole thing into a function. That will make the start_dashboard logic cleaner and get rid of boolean loop-terminator scan_ports. Just exit the loop by returning the answer.
def next_free_port( port=1024, max_port=65535 ):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while port <= max_port:
try:
sock.bind(('', port))
sock.close()
return port
except OSError:
port += 1
raise IOError('no free ports')
def start_dashboard():
# pass optional second parameter "max_port" here, else scan until a free one is found
port = next_free_port( os.getenv('DASHBOARD_PORT_ENV_VAR', 8008) )
dashboard.configure(port=port)
dashboard.launch()
You can use netcat to make ports in-use for testing: nc -l -p 9999 will listen on port 9999; press control-C to end it.
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
edited yesterday
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
answered 2 days ago
Oh My GoodnessOh My Goodness
1,809314
1,809314
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
|
show 1 more comment
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
Thank you for the answer, check is local, so no firewall in place.
$endgroup$
– spicyramen
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
I mean a host firewall, like iptables on Linux.
$endgroup$
– Oh My Goodness
2 days ago
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
$begingroup$
Sounds good, any recommendation for Python style? Thanks
$endgroup$
– spicyramen
yesterday
1
1
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
$begingroup$
the code can be a little shorter and clearer; see edits for a fleshed-out example.
$endgroup$
– Oh My Goodness
yesterday
1
1
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
$begingroup$
Thank you! Great sample
$endgroup$
– spicyramen
yesterday
|
show 1 more comment
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