You can use the following tools (Linux and open source) to troubleshoot network problems:
netstat: Displays information related to open ports on your server. Lets you view listeners and various IP addresses, such as the TCP output state.
netcat: A networking utility that reads and writes data across network connections, using the TCP/IP protocol. Netcat is useful for checking connectivity with the user store.
ldapsearch: An LDAP search tool useful for the Administration Console and Identity Server. For example, you can generate an LDAP search/bind matching what the Identity Server sends, to confirm whether an issue is with the Identity Server JAR files.
tcpdump: A command line tool for monitoring network traffic. Captures and displays packet headers and matches them against a set of criteria.
LDAP Browser/Editor: Lets you export configuration information to a file, and to confirm that Access Manager objects and attribute values are valid in an AccessManagerContainer. A number of open source versions are available from the Internet.