OSError [Errno 99] - python

Question

i want to execute the following simple server code:

import socket

s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 22331                # Reserve a port
s.bind((host, port))        # Bind to the port

s.listen(5)                 # Now wait for client connection.
while True:
   c, addr = s.accept()     # Establish connection with client.
   print('Got connection from', addr)
   c.send('Thank you for connecting')
   c.close()

gives the following error while executing:

OSError: [Errno 99] Cannot assign requested address

why the OS cannot bind the specified port with the address?

You probably want `host = '0.0.0.0'`. `socket.gethostname()` returns the hostname, not an IP address. — Valentin Lorentz, May 24 '14 at 09:04
I agree with @ValentinLorentz, you should try to be specific about the IP or use `0.0.0.0`. It looks like your `gethostname()` returns an IP / name that doesn't resolve to an IP address present on the host you're executing the script from. — Romuald Brunet, May 24 '14 at 11:24
The code you mentioned in your question is not generating this error. It worked fine on Windows 8 with python v2.7. Please show us the client side code too! — ρss, May 24 '14 at 11:36
@ValentinLorentz should it be host=IPAddress rather than host name in order to be bound? — Maria, May 24 '14 at 11:58
@ρss i didn't run the client yet, because the server is not running/ listening. — Maria, May 24 '14 at 12:01
@maria simply try this `host = '0.0.0.0'` and see what happens? — ρss, May 24 '14 at 12:02
@maria As I mentioned before your code works fine for me even if you give a hostname or an IP. — ρss, May 24 '14 at 12:17

Padraic Cunningham · Accepted Answer · 2014-05-24T13:32:06.367

1

If it works using the ip address but not using hostname.

You should have something like this in your /etc/hosts mapping ip to hostname.

127.0.0.1   localhost
127.0.1.1   your_hostname_here

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Your /etc/hostname should obviously be the same as above.

Reboot and you should be able to ping your hostname successfully.

You can also use socket.gethostbyname(socket.gethostname()) to get the i.p as opposed to the hostname

edited May 24 '14 at 13:32

answered May 24 '14 at 09:14

Padraic Cunningham

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As a side note: it might take a minute or so for the port to be available after killing the process. – Daniel May 24 '14 at 09:43
2

Nope, this specific error is usually `[Errno 48] Address already in use` – Romuald Brunet May 24 '14 at 11:22
i have checked and this port is not in use – Maria May 24 '14 at 12:03
what happens when you ping your hostname? – Padraic Cunningham May 24 '14 at 12:20
100% packet loss, my hostname is resolved to my network public address, i can ping my private IP address but not the public – Maria May 24 '14 at 12:31
@maria what is in /etc/hosts and /etc/hostname? – Padraic Cunningham May 24 '14 at 12:34
the /etc/hosts only shows the loopback address and somelines for IPv6 and /etc/hostname shows the name of my computer (cs) – Maria May 24 '14 at 12:38
ok I will edit my answer to avoid having a lot of comments. you need to add details to etc/hosts – Padraic Cunningham May 24 '14 at 12:40
tnx, it is fixed, the problem was with the hosts file, i have changed the host name but didn't edited the file, so it was showing something rather than my host name, now i added the host name and it is working. – Maria May 24 '14 at 13:53

score 1 · Answer 2 · answered May 24 '14 at 12:54

1

Try set the SO_REUSEADDR option to the socket:

s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

answered May 24 '14 at 12:54

mitnk

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OSError [Errno 99] - python

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