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The main purpose of TULIP Central Reflector is to proxy the TULIP queries to landmarks in PlanetLab's Scriptroute service, and the perfSONAR and PingER reverse ping servers. The PlanetLab Scriptroute service provides a cookie which works for a single IP address only. So in this way all the requests will be issued from the Central reflector and the responses will be sent back to the TULIP JNLP Client.
Implementation
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Requirements
- Should fetch sites.txt or have a local copy of sites.txt, what changes should be made to sites.txt ?
- A new parameter should be added to sites.txt to include teir0 or tier1. Also the region of tier1 sites needs to be specified in sites.txt
- A separate thread should be used for each landmark and Semaphores should be used for locking, so that data from different threads should not inter-mix.
- There should be a limit on the number of threads that can be launched at a time (say 10).
- Should there be extra logging on the reflector or can we rely on the standard web logs which will log each query including time stamp, the client name. What else it logs depends on whether the request is Get or a Post.
- Where are the results parsed, could be in the reflector or in the Java client. In the client distributes the parsing load, reduces the load on the reflector, simplifies the CGI script.
- What should happen if a landmark responds with a bad data. ( Should it process the error or send the raw data back?). Since there will be some anomalies I suspect the reflector will need to return the full response and anyhow needs to inform the user, so I suspect initially the client will process the response and spot errors etc.) Also if the client parses the result it will probably be easily able to spot problems.
- Special consideration for security as the script ultimately has to be deployed at SLAC (Perl taint option, warning option, special open method etc)
- Need to agree on a common format for the exchange of data.
- Needs a blacklisting mechanism for malicious hosts.
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Errors Reported by PlanetLab
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ERROR: you're (134.79.18.134) already running a measurement on socket 14. [http://128.83.122.179]
10 packets transmitted, 0 received, 100% packet loss, time 0 ms rtt min/avg/max = 0/0/0 [http://141.149.218.208]
Can't resolve DNS: submitted:6:in `ip_dst=': unable to resolve $target: running in a chroot without dns support (RuntimeError)
submitted:9: warning: didn't see packet 5 leave: pcap overloaded or server bound to incorrect interface?
To 134.79.16.9 timed out
Error connecting: Connection refused
ERROR: you need a valid scriptroute authentication cookie to use this server, or the cookie you used does not match\
your client IP 134.79.18.163; go to [http://www.scriptroute.org/cookies.html] to get one.
ERROR: you're (134.79.18.134) already running a measurement on socket 10.
PlanetLab Server Error: Received: IP (tos 0xc0, ttl 253, id 51592, offset 0, flags \ [none\], length: 56)
192.70.187.218 > 198.82.160.220: icmp 36: time exceeded in-transit
Error connecting: No buffer space available
submitted:9:in `send_train': scriptrouted error: unable to send to 137.138.137.177: No buffer space available (ScriptrouteError)
Parsing the SLAC Landmarks
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We have also considered whether the knowledge that a machine and possibly the usual owner can be accurately located may violate some privacy issue. This may require us to add some fuzz to results. So far this has not been done.
Sample Scripts
traceroute.pl: This script has been written with special security considerations so it will help in implementing reflector.cgi
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