OSX: remote control listening on wrong interface (external IP address instead of localhost)

[Polarbear-j]

When josm is started while the ethernet interface is up, it listens
to the ethernet IP address instead of localhost.

When ethernet is up but IPv4/DHCP disabled, josm listens to the external
IPv6 address.

When the ethernet status is being changed while josm is already running,
this has no influence.

Environment: MacOS 10.8.5 Java 1.8.0_25-b17, WLAN is off.

INFO: RemoteControl::Accepting connections on port 8111
INFO: RemoteControl::Accepting secure connections on port 8112

telnet localhost 8111

Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
Trying fe80::1...
telnet: connect to address fe80::1: Connection refused
telnet: Unable to connect to remote host

(same for 8112)

telnet 192.168.1.### 8111

Trying 192.168.1.###...
Connected to macbookpro-###mac-addr###.fritz.box.
Escape character is '^{]'.
GET /
...
Server: JOSM RemoteControl}

lsof -i:8111

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
java 2668 ###me### 67u IPv6 0x##### 0t0 TCP macbookpro-###mac-addr###.fritz.box:8111 (LISTEN)

Now, I unplug eth before starting josm, and replug once running:

telnet localhost 8111

Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
[bingo!]

lsof -i:8111

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
java 2687 ###me### 67u IPv6 0xe######## 0t0 TCP localhost:8111 (LISTEN)

the "last warnings" below are due to the disconnected network:

Revision: 7787
Repository Root: http://josm.openstreetmap.de/svn
Relative URL: ^/trunk
Last Changed Author: Don-vip
Last Changed Date: 2014-12-11 00:15:17 +0100 (Thu, 11 Dec 2014)
Build-Date: 2014-12-11 02:33:43
URL: http://josm.openstreetmap.de/svn/trunk
Repository UUID: ###
Last Changed Rev: 7787

Identification: JOSM/1.5 (7787 en) Mac OS X 10.8.5
Memory Usage: 347 MB / 910 MB (293 MB allocated, but free)
Java version: 1.8.0_25, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM

Plugins:
- FastDraw (30762)
- HouseNumberTaggingTool (30762)
- InfoMode (30737)
- PicLayer (30762)
- RoadSigns (30788)
- buildings_tools (30762)
- lakewalker (30737)
- log4j (30762)
- measurement (30737)
- proj4j (30738)
- reverter (30737)
- tageditor (30738)
- terracer (30737)
- turnlanes (30737)
- turnrestrictions (30762)
- undelete (30762)
- utilsplugin2 (30762)
- waydownloader (30762)
- wikipedia (30780)

Last errors/warnings:
- W: Mappaint style "standard" (Maxspeed) icon "maxspeed_icon.svg" not found.
- E: java.net.UnknownHostException: api.openstreetmap.org
- E: org.openstreetmap.josm.io.OsmTransferException: Could not connect to the OSM server. Please check your internet connection.. Cause: java.net.UnknownHostException: api.openstreetmap.org
- E: java.net.UnknownHostException: api.openstreetmap.org
- W: org.openstreetmap.josm.io.OsmTransferException: Could not connect to the OSM server. Please check your internet connection.. Cause: java.net.UnknownHostException: api.openstreetmap.org

[Polarbear-j]

Might be the solution for #10411

[Polarbear-j]

RemoteControlHttpServer.java calls InetAddress.getByName(Main.pref.get("remote.control.host", "localhost")));

Testing this code:

import java.net.InetAddress;
import java.net.UnknownHostException;

class TestName {
    public static void main(String[] args) {
        InetAddress ip;
        String hostname;
        try {
            ip = InetAddress.getLocalHost();
            hostname = ip.getHostName();
            System.out.println("getLocalHost(): " + ip);
            System.out.println("ip.getHostName(): " + hostname);

            ip = InetAddress.getByName("localhost");
            hostname = ip.getHostName();
            System.out.println("getByName(localhost): " + ip);
            System.out.println("ip.getHostName(): " + hostname);

        } catch (UnknownHostException e) {

            e.printStackTrace();

        }
    }
}

When I use that on my machine while en0 is up, I get

getLocalHost(): localhost/127.0.0.1
ip.getHostName(): localhost
getByName(localhost): localhost/192.168.1.###
ip.getHostName(): localhost

when en0 is unplugged

getLocalHost(): localhost/127.0.0.1
ip.getHostName(): localhost
getByName(localhost): localhost/127.0.0.1
ip.getHostName(): localhost

[Don-vip]

I got the exact opposite results on Windows 8.1 (same results with Java 7u72 and 8u25):

getLocalHost(): <Windows machine name>/192.168.0.###
ip.getHostName(): <Windows machine name>
getByName(localhost): localhost/127.0.0.1
ip.getHostName(): localhost

Same situation with my Linux server (Ubuntu 14.04 LTS)

getLocalHost(): #########.######.com/###.###.###.###
ip.getHostName(): #########.######.com
getByName(localhost): localhost/127.0.0.1
ip.getHostName(): localhost

So our method looks good. Only it does not seem to work for some OSX machines?

[Don-vip]

In 7800/josm:

fix #10833 - robustness to localhost name resolution for remote control

[Don-vip]

Thanks for the investigation!

[Don-vip]

Ticket #10411 has been marked as a duplicate of this ticket.

[Polarbear-j]

Testing latest 7801, unfortunately the issue is not fixed yet.
However the INFO line is more descriptive:

INFO: RemoteControl::Accepting connections on localhost/192.168.1.#:8111
INFO: RemoteControl::Accepting secure connections on localhost/192.168.1.#:8112

which is confirmed by lsof:

lsof -i:8111 -i:8112
COMMAND  PID     USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
java    2043 (me)   88u  IPv6 #      0t0  TCP macbookpro-#.fritz.box:8111 (LISTEN)
java    2043 (me)   89u  IPv6 #      0t0  TCP macbookpro-#.fritz.box:8112 (LISTEN)

This article was discussing some issues in finding the correct interface:
​http://crunchify.com/how-to-get-server-ip-address-and-hostname-in-java/

[Polarbear-j]

A workaround is to set remote.control.host=127.0.0.1 instead of the current default remote.control.host=localhost.
Is there a reason why we won't use the numeric IP address in the first place?

[Don-vip]

In 7826/josm:

fix #10833 - simplify remote control interface management: listen on 127.0.0.1 instead of localhost

[stoecker]

You know that you kill "::1" with this? localhost is not 127.0.0.1 anymore.

[Don-vip]

Are there ipv6-only systems out there?

[Don-vip]

In 7830/josm:

fix #10833 - simplify remote control interface management: let Java return the local loopback interface by itself

[stoecker]

Replying to Don-vip:

Are there ipv6-only systems out there?

Don't know. But there are systems, where localhost is IPV6 only which gave me really a lot of fun in the past.