A number of people have been asking for a way to check transaction ID randomness, in addition to source port randomness. OARC's porttest tool has now been expanded to also report on transaction IDs. To use it, issue a TXT query for the name txidtest.dns-oarc.net. For example, with dig:
$ dig +short txidtest.dns-oarc.net TXT " is GREAT: 26 queries in 2.7 seconds from 26 txids with std dev 20574.11"
Also note that in conjunction with this enhancement, the scoring critera for porttest and txidtest have been changed to match the web-based port test. The scoring is as follows:
Rating Standard Deviation Bits of Entropy
GREAT 3980 -- 20,000+ 13.75 -- 16.0
GOOD 296 -- 3980 10.0 --13.75
POOR 0 -- 296 0 -- 10.0