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Summary
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Protocol
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Port
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Direction relative to server
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Application
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UDP
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17335
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IN
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GPS report from cars
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IN/OUT
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Think GIS communication
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TCP
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17335
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IN/OUT
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Think GIS connections to server
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Note: 17335 is the default port used by the AVL Service, but this can be changed. The port used being used by the system is indicated in the Input settings of AVL Administrator.
Details
1) Public IP Address: The GPS equipment in each vehicle is programmed to send UDP packets to the AVL server. These packets typically arrive across the Internet. This requires that the computer running the AVL Server software be accessible across the Internet via a static IP address (i.e. "public IP Address"). Contact the Internet service provider (ISP) if unsure. An alternate solution to having a static IP address is to subscribe to domain name service such as www.no-ip.com.
2) UDP Routing: The internal network must correctly route all incoming UDP packets on port 17335 from the vehicles to the AVL Server. The network hardware and software firewalls must permit unsolicited UDP packets on this port to make it to the AVL Server. WTH has a TestTalker and TestListener program for confirming that this UDP path is open.
3) TCP Routing: Think GIS workstations will view the live fleet information either across the local network or the Internet via a TCP connections to the AVL Server on port 17335. The connection will be initiated by Think GIS and then data will be sent and received across this connection. Therefore the customer's router must route incoming TCP connection requests to the AVL Server and any hardware or software firewalls should allow the sending and receiving of TCP packets on this port. The AVL Administrator software also accesses the server via a TCP connection on this same port. WTH has a TcpTestServer and TcpTestClient program for testing TCP connectivity from computer to computer.
4) Supplimental Software: In addition to the above requirements, some supplemental WTH software may require both incoming and outgoing traffic on UDP port 17335. Many times, these should be considered unsolicited packets.
5) Testing: Networks can contain multiple routers and firewalls; therefore, no assumptions can be made simply by confirming one configuration. The only way to confirm that the COMPLETE UDP or TCP path is open is to actually perform a test. WTH has a test client and test server program for both UDP and TCP testing.
TestTalker.exe- Use to send UDP packets
TestListener.exe- Use to receive UDP packets
TcpTestServer.exe- Use to test TCP connections
TcpTestClient.exe- Use to test TCP connections
6) Some Common Problems:
Port forwarding is not configured on the router: Some of the above scenarios require that computers or devices outside of the local network send UDP packets or make TCP connections to the server. Typically the remote software or GPS modem is programmed to send this information to the agency's "public IP address." This is the IP address of the agency's router. Once a packet or connection request gets to the router it needs to know what local IP address on the network to forward the information to. This requires that router is programmed to "forward" incoming TCP and UDP traffic on port 17335 to the IP address of the AVL server.
Port forwarding on router is not configured for correct protocol: Quite often the above mentioned port forwarding was setup but only for UDP or only for TCP. Both protocols need to be set up to be forwarded to the AVL server.
Network Firewall is blocking communication: Most networks have some type of firewall to prevent unwanted traffic from the Internet and sometimes to even prevent unwanted traffic from going out. Sometimes this firewall is built into the router but sometimes it is separate. In either case, independent of any port forwarding setup the firewall must be configured to allow the UDP and TCP transmissions as described above.
Software Firewalls: A software firewall, such as Windows Firewall, running on the AVL server computer will stop any incoming UDP or TCP transmissions unless it is specifically configured to permit these applications or protocols to work. Even if the Windows Firewall is disabled or not running, there may be a 3rd party firewall running.
Other Routers or Firewalls: It should not be assumed that a public facing router or firewall is the only one on the network between the AVL server and the outside world. There may be others that also need configured.
Using Wrong IP address: The IP address that a computer on the agency's network uses to access the server is different than the one a computer outside of the same network uses.
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