lein repl error:Connection refused - clojure

Question

I installed leiningen on my Ubuntu, but it throws a "Connection refused" error when I run lein repl. Here's the error:
$ lein repl
Exception in thread "Thread-4" java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at clojure.tools.nrepl$connect.doInvoke(nrepl.clj:184)
at clojure.lang.RestFn.invoke(RestFn.java:421)
at clojure.tools.nrepl.ack$send_ack.invoke(ack.clj:47)
at clojure.tools.nrepl.server$start_server.doInvoke(server.clj:146)
at clojure.lang.RestFn.invoke(RestFn.java:619)
at user$eval540.invoke(NO_SOURCE_FILE:0)
at clojure.lang.Compiler.eval(Compiler.java:6619)
at clojure.lang.Compiler.eval(Compiler.java:6609)
at clojure.lang.Compiler.eval(Compiler.java:6582)
at clojure.core$eval.invoke(core.clj:2852)
at leiningen.core.eval$fn__3577.invoke(eval.clj:304)
at clojure.lang.MultiFn.invoke(MultiFn.java:231)
at leiningen.core.eval$eval_in_project.invoke(eval.clj:326)
at clojure.lang.AFn.applyToHelper(AFn.java:167)
at clojure.lang.AFn.applyTo(AFn.java:151)
at clojure.core$apply.invoke(core.clj:619)
at leiningen.repl$server$fn__7443.invoke(repl.clj:201)
at clojure.lang.AFn.applyToHelper(AFn.java:159)
at clojure.lang.AFn.applyTo(AFn.java:151)
at clojure.core$apply.invoke(core.clj:617)
at clojure.core$with_bindings_STAR_.doInvoke(core.clj:1788)
at clojure.lang.RestFn.invoke(RestFn.java:425)
at clojure.lang.AFn.applyToHelper(AFn.java:163)
at clojure.lang.RestFn.applyTo(RestFn.java:132)
at clojure.core$apply.invoke(core.clj:621)
at clojure.core$bound_fn_STAR_$fn__4102.doInvoke(core.clj:1810)
at clojure.lang.RestFn.invoke(RestFn.java:397)
at clojure.lang.AFn.run(AFn.java:24)
at java.lang.Thread.run(Thread.java:722)
I had saw a question like this at github:lein repl error, but it doesn't solve my problem. Anyone knows why?
environment
os: ubuntu 12.04
leningen: Leiningen 2.3.4
java: 1.7.0_21

Answer 1

First of all your stack trace is missing the Caused by... original exception.I didn't experienced it but I has been able to reproduce it getting the same stacktrace j plus these lines
Caused by: java.net.UnknownHostException: i7mito: System error
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:894)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1286)
at java.net.InetAddress.getLocalHost(InetAddress.java:1462)
... 36 more
if I removed my machine name (i7mito) from the /etc/hosts/ file and I left it like
127.0.0.1 localhost
So my guess is that lein relies on the DNS to resolve your machine name ( i7mito in my case) to an IP address. The first step in this name resolution is your hosts file so I would check that first. I realized that the IP you bind to localhost doesn't matter, it's the IP that it's binded to the result of the hostname command what matters.
So if you ensure that your machine name it's mapped to 127.0.0.1 on the /etc/hosts file it may work. If it doesn't check your network configuration as other users are pointed out as it seems something related.
Hope it helps, of course this applies if you get the same extra lines on the stacktrace :)