Mac OS X 10.7 can't ping/telnet localhost

Question

I'm developing using django/postgresql on Mac OS X 10.7 and suddenly I am unable to access the test server through http://localhost:8000/. I can make it listen on 0.0.0.0:8000 and then it works...

Then I noticed problems with SABnzbd starting up. Whenever I try to start it, it dies and shuts down. The logs show

IOError: Port 8080 not bound on '127.0.0.1'

running netstat -an | grep 8080 shows that there is nothing actually listening on port 8080.

I then tried to telnet and ping localhost. Neither work. When I telnet, I get:

$ telnet localhost
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...

and it just hangs there.

When I try to ping I get the following:

$ ping localhost
PING localhost (127.0.0.1): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2

The weird thing is that when I telnet to port 80 it works!

$ telnet localhost 80
Trying ::1...
Connected to localhost.
Escape character is '^]'.

My /etc/hosts file seems normal:

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost 
fe80::1%lo0     localhost

Is there any way for me to fix this problem or is it easiest for me to just wipe it and start again?

Solution

Most firewalls block ping requests now, my OSX Lion install had that behavior by default too.

Try browsing to http://localhost:80 if you can connect to port 80, and look what's running on that port. Also take look at your Sharing Preferences - there used to be a Web Site sharing feature, and that might be using port 80.

Also, try telnetting to localhost:8080, and see if you can connect (if you can, another app is using that port).

Try to open http://localhost:8080 in your browser then, to try to find out what program is running on that port.

Comments

[fixer1234]

possible duplicate of Mac OS X Mountain Lion can't ping/telnet localhost. Point to a wrong public IP

[Michael]

I can't telnet localhost:8080 or get to localhost:8080, both hang there. From what I can see, the firewall is turned off. Am I missing something?

[friedkiwi]

Do you have Little Snitch (or compareable) running - saw that behavior over here too when running that.

[Michael]

Nope, I don't even have it on my computer.

[G-Man Says 'Reinstate Monica']

The question includes command output that shows that "localhost" is getting resolved to 127.0.0.1 and ::1, so that isn't the issue here.