squid3

Это?
#  TAG: quick_abort_min (KB)
#  TAG: quick_abort_max (KB)
#  TAG: quick_abort_pct (percent)
#       The cache can be configured to continue downloading aborted
#       requests.  This may be undesirable on slow (e.g. SLIP) links
#       and/or very busy caches.  Impatient users may tie up file
#       descriptors and bandwidth by repeatedly requesting and
#       immediately aborting downloads.
#
#       When the user aborts a request, Squid will check the
#       quick_abort values to the amount of data transfered until
#       then.
#
#       If the transfer has less than 'quick_abort_min' KB remaining,
#       it will finish the retrieval.  Setting 'quick_abort_min' to -1
#       will disable the quick_abort feature.
#
#       If the transfer has more than 'quick_abort_max' KB remaining,
#       it will abort the retrieval.
#
#       If more than 'quick_abort_pct' of the transfer has completed,
#       it will finish the retrieval.
#
#Default:
# quick_abort_min 16 KB
# quick_abort_max 16 KB
# quick_abort_pct 95