[rabbitmq-discuss] Plz give me help about EPMD: Non-local peer connected

Mon Jul 9 07:32:25 BST 2012

Hi Tim,

Thanks for your reply.

I tried "erl -sname rabbit", it's OK.

my /etc/hosts looks like following:
127.0.0.1    game-01 ZSWY76 localhost.localdomain localhost
::1        localhost6.localdomain6 localhost6

EPMD can be started successfully, but always reports "Non-local peer connected" then force disconnecting rabbit-server.

Did I forget any necessory configration for RabbitMQ to use loopback interface to connect epmd？

Thanks a lot.

He Bin

> Date: Fri, 6 Jul 2012 18:34:07 +0100
> From: tim at rabbitmq.com
> To: rabbitmq-discuss at lists.rabbitmq.com
> CC: hebin7611 at hotmail.com
> Subject: Re: [rabbitmq-discuss] Plz give me help about EPMD: Non-local peer connected
> 
> Hi there,
> 
> On 06/07/2012 06:53, 何斌 wrote:
> > Hi all,
> >
> > I installed RabbotMQ & tried to start it.
> >
> > But I always got error as following:
> >
> 
> Ok so first of all, let's see if we can get you to start a stand alone 
> distributed Erlang node successfully. Normally stack traces like that 
> occur when the host environment isn't set up quite right (from Erlang's 
> perspective).
> 
> We need to be able to run `erl -sname rabbit` on the command line and 
> see the Erlang emulator start successfully. It should look something 
> like this:
> 
> ##############
> 
> t4 at malachi:systest $ erl -sname rabbit
> Erlang R15B01 (erts-5.9.1) [source] [64-bit] [smp:2:2] [async-threads:0] 
> [hipe] [kernel-poll:false]
> 
> Eshell V5.9.1  (abort with ^G)
> (rabbit at malachi)1>
> 
> ##############
> 
> Can you start Erlang like that successfully? I'm assuming not, but 
> please let us know.
> 
> I'm also interested in understanding what your hosts configuration 
> (e.g., /etc/hosts) looks like. On some Operating Systems (such as CentOS 
> for example), failing to set an explicit host name prevents you from 
> starting a distributed Erlang node.
> 
> > {error_logger,{{2012,7,6},{13,32,21}},"Protocol: ~p: register error:
> > ~p~n",["inet_tcp",{{badmatch,{error,epmd_close}},[{inet_tcp_dist,listen,1,[{file,"inet_tcp_dist.erl"},{line,70}]},{net_kernel,start_protos,4,[{file,"net_kernel.erl"},{line,1314}]},{net_kernel,start_protos,3,[{file,"net_kernel.erl"},{line,1307}]},{net_kernel,init_node,2,[{file,"net_kernel.erl"},{line,1197}]},{net_kernel,init,1,[{file,"net_kernel.erl"},{line,357}]},{gen_server,init_it,6,[{file,"gen_server.erl"},{line,304}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,227}]}]}]}
> > {error_logger,{{2012,7,6},{13,32,21}},crash_report,[[{initial_call,{net_kernel,init,['Argument__1']}},{pid,<0.20.0>},{registered_name,[]},{error_info,{exit,{error,badarg},[{gen_server,init_it,6,[{file,"gen_server.erl"},{line,320}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,227}]}]}},{ancest
> > ors,[net_sup,kernel_sup,<0.9.0>]},{messages,[]},{links,[#Port<0.90>,<0.17.0>]},{dictionary,[{longnames,false}]},{trap_exit,true},{status,running},{heap_size,987},{stack_size,24},{reductions,551}],[]]}
> > {error_logger,{{2012,7,6},{13,32,21}},supervisor_report,[{supervisor,{local,net_sup}},{errorContext,start_error},{reason,{'EXIT',nodistribution}},{offender,[{pid,undefined},{name,net_kernel},{mfargs,{net_kernel,start_link,[[rabbitmqprelaunch1077,shortnames]]}},{restart_type,permanent},{shutdown,2000},{child_type,worker}]}]}
> > {error_logger,{{2012,7,6},{13,32,21}},supervisor_report,[{supervisor,{local,kernel_sup}},{errorContext,start_error},{reason,shutdown},{offender,[{pid,undefined},{name,net_sup},{mfargs,{erl_distribution,start_link,[]}},{restart_type,permanent},{shutdown,infinity},{child_type,supervisor}]}]}
> > {error_logger,{{2012,7,6},{13,32,21}},std_info,[{application,kernel},{exited,{shutdown,{kernel,start,[normal,[]]}}},{type,permanent}]}
> > {"Kern el pid
> > terminated",application_controller,"{application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}}"}
> >
> > Crash dump was written to: erl_crash.dump
> > Kernel pid terminated (application_controller)
> > ({application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}})
> >
> >
> > I ran it on a server with public IP 183.*.*.* .
> >
> > In Erlang src, I found that epmd checks connection src.
> >
> >        /* Determine if connection is from localhost */
> >        if (getpeername(s->fd,(struct sockaddr*) &si,&st) ||
> >            st < sizeof(si)) {
> >            /* Failure to get peername is regarded as non local host */
> >            s->local_peer = EPMD_FALSE;
> >        } else {
> >            /* Only 127.x.x.x and connections from the host's IP address
> >               allowed, no false positives */
> >            s->local_peer =
> > (((((unsigned) ntohl(si.sin_addr.s_addr)) & 0xFF000000U) ==
> >                 0x7F000000U) ||
> > (getsockname(s->fd,(struct sockaddr*) &di,&st) ?
> >                 EPMD_FALSE : si.sin_addr.s_addr == di.s in_addr.s_addr));
> >        }
> >        dbg_tty_printf(g,2,(s->local_peer) ? "Local peer connected" :
> >                       "Non-local peer connected");
> >
> >
> > But unfortunately, si.sin_addr.s_addr was 183.*.*.*, while
> > di.sin_addr.s_addr was 127.0.0.1
> >
> > My log：Checking peer address, getsockname ret: 0, si_addr=0xb7??????,
> > di_addr=0x7f000001
> >
> >
> 
> I could be wrong, but I suspect this is a red herring. You can restart 
> epmd with -d to get debugging information as well, but I suspect this 
> isn't relevant.
> 
> Is there any way to force RabbitMQ server connect epmd via a specified
> > address？
> >
> 
> I'm not really sure what you mean by this, but I'm fairly confident that 
> it is not necessary to even attempt to do something like that. Erlang 
> should be able to start up nodes with `-sname <name>` or `-name 
> <name>@<host>` and if either doesn't work, a little tweaking of the host 
> configuration should solve it.
> 
> Based on your original comment (starting rabbitmq but always getting an 
> error) my understanding is that you're trying to start rabbit on this 
> machine and it fails. AFAIK when a distributed Erlang node connects to 
> EPMD on the localhost it should be treated as such. The rabbitmq-server 
> script starts rabbit up with `-sname rabbit` which implies that the node 
> name will be rabbit@<hostname> so you should make sure that `erl -sname 
> rabbit` works first of all.

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