Tor的全称是"The Onion Router"号称是"An anonymous Internet communicaton system"，它针对现阶段大量存在的流量过滤、嗅探分析等工具，在JAP之类软件基础上改进的，支持Socks5，并且支持动态代理链（通过Tor访 问一个地址时，所经过的节点在Tor节点群中随机挑选，动态变化，由于兼顾速度与安全性，节点数目通常为2-5个），因此难于追踪，有效地保证了安全性。另一方面，Tor 的分布式服务器可以自动获取，因此省却了搜寻代理服务器的精力。
Changes in version 0.1.2.15 - 2007-07-17
o Major bugfixes (compilation):
- Fix compile on FreeBSD/NetBSD/OpenBSD. Oops.
o Major bugfixes (crashes):
- Try even harder not to dereference the first character after
an mmap(). Reported by lodger.
- Fix a crash bug in directory authorities when we re-number the
routerlist while inserting a new router.
- When the cached-routers file is an even multiple of the page size,
don't run off the end and crash. (Fixes bug 455; based on idea
- Fix eventdns.c behavior on Solaris: It is critical to include
orconfig.h _before_ sys/types.h, so that we can get the expected
definition of _FILE_OFFSET_BITS.
o Major bugfixes (security):
- Fix a possible buffer overrun when using BSD natd support. Bug
found by croup.
- When sending destroy cells from a circuit's origin, don't include
the reason for tearing down the circuit. The spec says we didn't,
and now we actually don't. Reported by lodger.
- Keep streamids from different exits on a circuit separate. This
bug may have allowed other routers on a given circuit to inject
cells into streams. Reported by lodger; fixes bug 446.
- If there's a never-before-connected-to guard node in our list,
never choose any guards past it. This way we don't expand our
guard list unless we need to.
o Minor bugfixes (guard nodes):
- Weight guard selection by bandwidth, so that low-bandwidth nodes
don't get overused as guards.
o Minor bugfixes (directory):
- Correctly count the number of authorities that recommend each
version. Previously, we were under-counting by 1.
- Fix a potential crash bug when we load many server descriptors at
once and some of them make others of them obsolete. Fixes bug 458.
o Minor bugfixes (hidden services):
- Stop tearing down the whole circuit when the user asks for a
connection to a port that the hidden service didn't configure.
Resolves bug 444.
o Minor bugfixes (misc):
- On Windows, we were preventing other processes from reading
cached-routers while Tor was running. Reported by janbar.
- Fix a possible (but very unlikely) bug in picking routers by
bandwidth. Add a log message to confirm that it is in fact
unlikely. Patch from lodger.
- Backport a couple of memory leak fixes.
- Backport miscellaneous cosmetic bugfixes.