JGRP000006 errors triggered by nmap TCP Connect scanning JGroups ports ---------------------------------------------------------------------- Key: JGRP-1947 URL: https://issues.jboss.org/browse/JGRP-1947 Project: JGroups Issue Type: Bug Affects Versions: 3.4.6 Environment: Java 7u80 x32 Tomcat 7.0.62 HA-JDBC 3.0.4-SNAPSHOT + JGroups 3.4.6 nmap 5.5.1 Reporter: Justin Cranford Assignee: Bela Ban Fix For: 3.6.5 I am running a two node Tomcat cluster. Both JGroups and Hazelcast are used for different parts of application clustering - JGroups for HA-JDBC, and Hazelcast for application locks outside of HA-JDBC. Hazelcast is not relevant to JGroups, except I included the Hazelcast errors because they happen at the same time as the JGroups JGRP000006 errors. This gave me a hint of why I see JGRP000006, because the Hazelcast error is more specific about root cause. Basically if I run a nmap TCP Connect scan on my servers like so, this opens/closes empty TCP connections. JGroups reports these events as JGRP000006, whereas Hazelcast reports them as "java.io.IOException[Connection reset by peer]". I am wondering if JGroups can handle these nmap TCP Connect scans more gracefully, or even log a more descriptive error with the JGRP000006 error code. My Tomcat errors for both JGroups and Hazelcast Jul 31, 2015 12:27:52 AM com.hazelcast.nio.SocketAcceptor INFO: [10.0.0.85]:5900 [ClusterManager] [3.2.4] Accepting socket connection from /10.0.0.86:40527 Jul 31, 2015 12:27:52 AM com.hazelcast.nio.TcpIpConnectionManager INFO: [10.0.0.85]:5900 [ClusterManager] [3.2.4] 5900 accepted socket connection from /10.0.0.86:40527 Jul 31, 2015 12:27:52 AM org.jgroups.logging.JDKLogImpl warn WARNING: JGRP000006: failed accepting connection from peer java.net.SocketException: Connection reset at java.net.SocketInputStream.read(Unknown Source) at java.net.SocketInputStream.read(Unknown Source) at java.io.BufferedInputStream.fill(Unknown Source) at java.io.BufferedInputStream.read1(Unknown Source) at java.io.BufferedInputStream.read(Unknown Source) at java.io.DataInputStream.readFully(Unknown Source) at org.jgroups.blocks.TCPConnectionMap$TCPConnection.readPeerAddress(TCPConnectionMap.java:494) at org.jgroups.blocks.TCPConnectionMap$TCPConnection.<init>(TCPConnectionMap.java:376) at org.jgroups.blocks.TCPConnectionMap$Acceptor.handleAccept(TCPConnectionMap.java:298) at org.jgroups.blocks.TCPConnectionMap$Acceptor.run(TCPConnectionMap.java:282) at java.lang.Thread.run(Unknown Source) Jul 31, 2015 12:27:52 AM com.hazelcast.nio.TcpIpConnection INFO: [10.0.0.85]:5900 [ClusterManager] [3.2.4] Connection [/10.0.0.86:40527] lost. Reason: java.io.IOException[Connection reset by peer] My nmap scan which triggers the JGRP000006 errors: root@myserver:~$ nmap -n -T4 -sT -PN --max-scan-delay 0ms --min-rate 1000000 --max-retries 0 -p 443,3306,5900,7900,7901 10.0.0.85 Starting Nmap 5.51 ( http://nmap.org ) at 2015-07-31 01:33 UTC Cannot find nmap-payloads. UDP payloads are disabled. Nmap scan report for 10.0.0.85 Host is up (0.00035s latency). PORT STATE SERVICE 443/tcp open https 3306/tcp open mysql 5900/tcp open vnc 7900/tcp open mevent 7901/tcp open unknown Nmap done: 1 IP address (1 host up) scanned in 0.04 seconds