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ICSI Netalyzr

Netalyzr is a java applet developed by ICSI which will let you do a whole bunch of Internet connectivity tests. This can be used to determine the Internet connection status of a machine, including NAT, firewall rules, DNS resolver and much more, which can be very helpful in debugging a PERT case.
Netalyzr currently supports the following tests:

  • NAT Detection (internal/external IP address)
  • DNS based host information (Tor/Spamhaus/SORBS DHUL)
  • outbound TCP reachability (FTP, SSH, SMTP, DNS, HTTP, POP3, RPC, NetBIOS, IMAP, SNMP, HTTPS, SMB, SMTP/SSL, secure IMAP, authenticated SMTP, IMAP/SSL, POP/SSL, remote SIP server, BitTorrent Server)
  • outbound UDP reachability (DNS, MSSQL (port 1434)
  • Path MTU discovery
  • Network latency measurement
  • TCP connection setup latency
  • Network background health measurement
  • Network bandwidth measurements Upload/Download
  • Network buffer measurements
  • HTTP proxy detection (address-based/header-based/malformed requests)
  • Filetype-based filtering (HTTP cache)
  • Javascript-based tests
  • domain DNS lookup (restricted/unrestricted)
  • Direct EDNS support
  • DNS resolver address
  • DNS resolver properties
  • DNS glue policy
  • DNS resolver port randomization
  • DNS lookups of popular domains
  • DNS external proxy
  • DNS results wildcarding
  • system clock accuracy
  • Browser properties
  • Uploaded Data

Here are some screenshots of the applet, so you get a feeling what it looks like:

  • Netalyzr Result Summary:


  • Netalyzr Expanded Summary:


  • Netalyzr Client Transcript:


  • Netalyzr Server Transcript:


– Main.ChrisWelti - 15 Jan 2010 - 18 Jan 2010

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