/00-report.txt
Secret
| Great Firewall Tor Probing Circa 09 DEC 2011 | |
| -------------------------------------------- | |
| Author: Tim Wilde, Team Cymru, Inc. <twilde@cymru.com> | |
| Date: 06 JAN 2012 | |
| This analysis was performed during the week of 05 DEC 2011 - 09 DEC 2011, in | |
| an attempt to determine the extent and type of blocking and probing being | |
| performed by the Great Firewall of China (henceforth "GFW") against | |
| unpublished Tor bridges located outside of China, but accessed from within | |
| China. | |
| These results are considered valid at the time of their collection (05-09 DEC | |
| 2011), and no guarantees are provided to their continuing validity beyond | |
| that time, due to the changing nature of anti-circumvention techniques and | |
| technologies. | |
| This analysis was originated based on Tor trac ticket #4185. A github | |
| "gist" of the results, including this report, can be found at | |
| https://gist.github.com/da3c7a9af01d74cd7de7 | |
| Pre-Analysis Conditions, Goals, and Assumptions | |
| ----------------------------------------------- | |
| Prior to the initiation of this round of analysis, it had been determined | |
| that any Tor bridge outside of China that was connected to by a client | |
| within China would be blocked by the GFW, usually within a matter of | |
| minutes. Previous analysis revealed that the Tor connection initiated by | |
| the client resulted in a series of probes from a variety of other IPs within | |
| China (varying from connection to connection), and, within minutes of those | |
| probes, the client's connection to the bridge would be blocked and could not | |
| be re-initiated. Blocking all connections to the bridge except from the | |
| intended client was shown to allow the connection to persist successfully | |
| for > 48 hours, thus showing a direct connection between the probing and | |
| blocking. This previous analysis was performed ad-hoc without dedicated | |
| attention/resources, and the analysis described in this report was performed | |
| as a follow-up under more stringent conditions to attempt to determine the | |
| exact parameters of probing and blocking. | |
| The primary goals of this analysis were: | |
| 1) Determine the extent of GFW probing of Tor connections, and more broadly, | |
| SSL sessions in general; what triggers the probing, what time considerations | |
| are involved, etc. | |
| 2) Determine how the decision to block is made. | |
| 3) Determine a course forward for Tor to circumvent probing and blocking. | |
| It is assumed that, despite a significant series of probes originating from | |
| a single host, the GFW does not change behavior to prevent us from learning | |
| what they are doing. This assumption has been tested with a smaller set of | |
| tests from some other hosts and appears to hold true, but cannot be | |
| conclusively proven. | |
| During the previous analysis it was noted that blocking appeared to be | |
| performed against specific destination IP:port pairings; attempting to | |
| connect to a new port on a host after a previous connection had been blocked | |
| was successful, but provoked new probing and blocking in the same way as the | |
| previous port. It is assumed that this destination IP:port pairing is still | |
| in use in current techniques. | |
| Summary of Conclusions | |
| ---------------------- | |
| Goal #2 was found to be unachievable at the time of analysis, as it was not | |
| possible throughout our testing to provoke blocking. Testing of connections | |
| to "new" published Tor relays (exact dates for "new" not determined) showed | |
| that even published Tor relays were connectable from within China. Once | |
| this was determined, focus shifted to understanding the probing and how it | |
| could be avoided (goals #1 and #3). | |
| With respect to goal #1, our testing showed that the GFW appears to perform | |
| "garbage binary" probes of the non-China side of any connection from China | |
| to TCP port 443 that performs an SSL negotiation. This probe is performed | |
| in near-real-time after the connection is established, implying | |
| near-line-rate deep packet inspection (DPI) capabilities. TCP/443 | |
| connections that did not actually exchange an SSL handshake, such as using | |
| the obfsproxy obfs2 protocol, did not provoke probing. At this time the | |
| purpose of this probe is unknown; further details of its contents and | |
| speculation as to its purpose can be found later in this report. | |
| A second type of probing, which appears to be specifically aimed at Tor, was | |
| also detected. This probing appeared to occur using a client that actually | |
| spoke SSL, and, within the SSL session, the Tor protocol, and was not | |
| activated in real-time, but appeared to be triggered to occur at regular 15 | |
| minute past the hour intervals if its conditions were met. Analysis showed | |
| that the Tor SSL cipher list was at least one significant component of the | |
| detection mechanism that initiated this probing; a client modified to remove | |
| a sincle cipher from the list, when connecting to an unmodified unpublished | |
| bridge in the United States, did not trigger probing. The SSL "client | |
| hello" packet was determined as a direct cause of the probing; when just | |
| that data was sent to an open Tor bridge from within China using netcat, the | |
| probing was triggered on the expected 15 minute interval. | |
| A connection between a Chinese client and a US unpublished bridge node over | |
| the obfsproxy obfs2 protocol was able to successfully persist for several | |
| days, including numerous disconnects/reconnects, without provoking any type | |
| of probing. | |
| Recommendations | |
| --------------- | |
| In the immediate term, modifying the Tor SSL client hello to present a list | |
| of ciphers more closely (ideally identically) matching that of a common | |
| commodity web browser would bypass the current probe trigger. In general, | |
| the items in Proposal 179 remain valid and a wise choice; the same eye | |
| should be cast towards the client hello, and an attempt made to match it as | |
| closely to commodity web browsers as possible. With both sides of that | |
| equation implemented, it becomes much more difficult for any authoritarian | |
| regime to distinguish Tor traffic from standard SSL traffic, requiring | |
| significantly more effort to locate unpublished bridge nodes and connections | |
| to them. | |
| In the longer term, the two problems that need to be solved are: | |
| 1) Client-server negotiation that is uniquely identifiable in any way. | |
| 2) The ability of an arbitrary adversary to, given a suspected Tor server | |
| IP:port combination, connect to that IP:port combination and perform a | |
| negotiation using the Tor protocol, or anything that can be uniquely | |
| identified to a Tor protocol negotiation. | |
| Problem #1 can be solved by a transport that either looks identical on both | |
| sides to a standard HTTPS SSL session, or that looks like nothing | |
| identifiable at all, like the obfs2 protocol provided by obfsproxy. | |
| Problem #2 is somewhat more difficult. Tor proposal 190 combined with the | |
| ideas in [0] is one method that has some promise. The "shared secret" | |
| implementation of obfs2 in obfsproxy is another, as an adversary attempting | |
| to initiate an obfs2 connection without the right shared secret would be | |
| unable to get anything but noise back from the server. That noise, however, | |
| which the server currently emits immediately upon connection in the current | |
| implementation, may be trivially fingerprintable, as it is not entirely | |
| common in the wild. | |
| [0] http://archives.seul.org/or/dev/Nov-2011/msg00073.html | |
| Methodology | |
| ----------- | |
| A single system within China was used to initiate connections to a series of | |
| Tor bridges provisioned within the Amazon EC2 cloud computing product, | |
| within the United States. EC2 was utilized to allow for rapid changing of | |
| IPs while maintaining toolsets and datasets, to eliminate possible | |
| black/whitelisting of IPs by the GFW. All test sessions were monitored with | |
| full packet captures generated on the bridge nodes, and at several points in | |
| the process Tor debug logs were captured from the bridge as well. | |
| Reasonable efforts were made to ensure that each test used a unique | |
| connection tuple to prevent cross-contamination. | |
| General probe observations | |
| -------------------------- | |
| All probes came from a wide range of IP addresses within China. A sampling | |
| of these IPs as collected through our analysis can be found on the following | |
| github gist: | |
| https://gist.github.com/4320b75d398f2e1f074d | |
| This is by no means an exhaustive list; we have not yet undertaken to | |
| attempt a fuller collection of probing IPs. It is also possible that this | |
| list contains false positives; it is simply a list of all IPs (other than | |
| those of our test systems) geolocated to China that were observed connecting | |
| to our unpublished bridges during the testing cycle; random scanning | |
| activity could have snuck in, but the majority are due to active probes. | |
| Each probing "session" generally consisted of multiple probes from multiple | |
| different IPs within China. p0f (passive OS fingerprinting) data collected | |
| during the probes indicated that they generally originated from Linux | |
| systems, but there was some conflicting data in the source ports used by | |
| some probes, which appeared in ephemeral port ranges more commonly seen on | |
| Windows systems. This data is not conclusive in any way due to the | |
| uncertain nature of p0f and the ability to reconfigure source port ranges at | |
| will in modern operating systems. | |
| Garbage binary probes | |
| --------------------- | |
| Any connection from China to TCP/443 of a host in the US that exchanged an | |
| SSL handshake, no matter what the certificates looked like (self-signed, | |
| CA-signed, etc) provoked what we have termed the "garbage binary" probes | |
| ("garbage probes" for short) against the US host. The only exception to | |
| this seemed to be "old" hosts, which is to say, long-established hosts that | |
| have had HTTPS services running for an extended period of time. Connections | |
| to those hosts did not appear to provoke any type of scanning activity. | |
| The garbage probes occurred within moments of the SSL negotiation. In some | |
| cases, the data sent by these probes was identical, even from different | |
| source hosts and at different times. | |
| Notably, garbage probes did not occur in the case of TCP/443 connections | |
| that spoke simple plaintext or non-SSL binary protocols, such as obfs2. | |
| This indicates that DPI was taking place, likely at or near line-rate, to | |
| select which hosts should be probed. | |
| Once a host was probed, subsequent connections with the same destination | |
| outside of China did not provoke probes for approximately the next 10 | |
| minutes (measured from the final packet in a sequence of probes). After 10 | |
| minutes, a new SSL negotiation between the hosts would trigger a new round | |
| of probing. The "ignored" interval remained consistent through many rounds | |
| of testing. | |
| We have not attempted to exhaustively collect and compare the data sent in | |
| these probes, but what analysis we have performed does not provide any | |
| insight into their purpose or intent. It is possible that these probes are | |
| designed to provoke a response from a different category of server that | |
| operates on TCP/443 (and possibly other ports) and that the Chinese | |
| government is intending to block, but that is only speculation at this time. | |
| It is not clear if further analysis would be worthwhile at this time given | |
| that these probes do not, at the surface, appear to be directed specifically | |
| at Tor. The lack of currently active blocking resulting from any probes | |
| also makes it difficult to evaluate the effectiveness of any changes that | |
| might result from such analysis. | |
| Full SSL/Tor probes | |
| ------------------- | |
| Our testing demonstrated that the SSL client hello sent by a Tor client in | |
| China to a US-based unpublished bridge will consistently trigger probing of | |
| the bridge by Chinese hosts, consisting of fully-established TCP, SSL, and | |
| Tor-protocol connections. Analysis of debug logs from bridges in this | |
| testing showed behavior consistent with a Tor client configured with | |
| multiple bridge statements. It is also possible, but impossible to | |
| determine definitively at this time, that the probers were using custom | |
| software either written from scratch or adapted from the Tor sources to | |
| perform their probing. | |
| Specifically, the debug logs and pcaps showed that the prober connected, | |
| performed an SSL handshake, performed an SSL renegotiation, and then spoke | |
| the Tor protocol. When speaking the Tor protocol, the probers we captured | |
| built a one-hop circuit and sent a BEGIN_DIR cell, as would be expected from | |
| a proper Tor client. When the bridge replies to the BEGIN_DIR cell with its | |
| descriptor, the prober hangs up the connection. | |
| This probing consistently took place within a range of +3 minutes from a 15 | |
| minute past the hour interval (HH:00, HH:15, HH:30, HH:45) after a Tor | |
| client SSL client hello was sent from China to the US host. Multiple | |
| connections were made in each round of probing. The probing occurred | |
| consistently regardless of the TCP source and destination ports - if a Tor | |
| SSL client hello packet was sent, on the next 15 minute interval a full | |
| Tor-speaking probe could be expected, like clockwork. | |
| Conversely, when the Tor SSL client hello was modified by removing a single | |
| cipher from the cipher spec, full Tor connections from China to a US | |
| unpublished bridge could be established multiple times, and for extended | |
| durations, without provoking any probing. Removing the less-common | |
| ServerName SSL extension from the client hello, however, did not change the | |
| probing behavior, indicating that the probe is likely tied specifically to | |
| the cipher specs, not to the entire hello packet. Unfortunately we were not | |
| able to verify if sending a raw set of cipher specs only would trigger the | |
| probing; this test was not performed before time on the analysis ran out. | |
| The SSL cipher list probe trigger is further discussed in Tor trac ticket | |
| #4744. | |
| Server-side SSL cert impacts | |
| ---------------------------- | |
| Before isolating the SSL client hello as the provoker of probing, we | |
| performed a number of tests using a simple SSL server on the US side and | |
| openssl s_client, wget, and Firefox on the China side to attempt to locate | |
| server SSL certificate combinations that provoked probing. As discussed in | |
| the garbage probing section, it appears that any SSL negotiation, even with | |
| a fully legitimate CA-signed cert (and having used the correct hostname in | |
| the cert to access the host, etc), will trigger the garbage probing. On | |
| non-standard ports, though, none of these clients provoked any type of | |
| probing, garbage or real SSL, no matter what the server certificate looked | |
| like. As such it does not appear that the GFW is, today, keying on the | |
| server certificate presented to make probing decisions. | |
| Traceroute testing | |
| ------------------ | |
| Mike Perry posited that the prober IPs could be legitimate IPs within China | |
| that are hijacked (partially or entirely by the GFW to perform its probes, | |
| and suggested some traceroute testing to attempt to confirm or deny this | |
| hypothesis. After several false starts, we were able to successfully source | |
| TCP traceroute packets to a prober IP using the exact same | |
| sourceIP:sourcePort:destIP:destPort tuple that was being used for the probe, | |
| during the probe and after the probe. These results did not show a | |
| different route during the probe and after the probe as Mike expected if | |
| such hijacking were taking place, so it does not appear likely, though it | |
| has not been conclusively disproven. | |
| Additional Data | |
| --------------- | |
| A number of other files are available in the github gist that contains this | |
| report, including: | |
| * testcases.txt - a list of planned test cases for the project, plotted out | |
| both before and during the project. Not all cases were tested as some | |
| were deemed irrelevant when actual blocking could not be replicated, and | |
| due to other results found during testing. | |
| * results.txt - a log of results obtained from working within the test cases | |
| described above. Somewhat terse and difficult to interpret for anyone | |
| other than the author, but included for completeness. | |
| Interpretation/annotation available upon request to the author. | |
| * general-notes.txt - a series of general notes and a set of tentative | |
| conclusions formed on the final two days of testing. These notes have | |
| largely been distilled, cleaned up, and expanded upon within this report. | |
| * traceroute.txt - traceroute output from the traceroute testing phase | |
| described in a previous section. | |
| * cn.log - hotpot.py output of some "garbage probes" collected early on in | |
| the process. | |
| * client-hello.raw - the raw bytes representing a Tor client's SSL client | |
| hello sent via netcat to provoke full Tor/SSL probing. | |
| Additionally, trusted researchers / Tor developers are welcome to contact | |
| the author for access to the pcaps and debug logs collected during this | |
| testing. Due to senstive contents (IPs of probing systems, etc), we cannot | |
| release these publicly at this time. | |
| Acknowledgements | |
| ---------------- | |
| Thanks to Team Cymru, Inc. for providing approximately a week of the | |
| author's time dedicated to this analysis, as well as the funding for the | |
| Amazon EC2 bridges and facilitating the access within China. Thanks to | |
| George Kadianakis (asn) for his analysis assistance and help providing | |
| direction for the testing, as well as the handy hotpot tool. Thanks also to | |
| too many Tor developers and other contributors in #tor-dev to count or list, | |
| but I'll try: nickm, armadev, rransom, Sebastian, and mikeperry. Apologies | |
| to those I missed, it's not because you were unhelpful, I promise you! | |
| Revision History | |
| ---------------- | |
| 06 JAN 2012 - Initial draft published | |
| 07 JAN 2012 - Minor revisions and additions per feedback from George | |
| Kadianakis. |
| 2011-12-05 18:25:46.223838 | '' | |
| 2011-12-05 18:26:53.720946 | '\x80w\x01\x03\x01\x00N\x00\x00\x00 \x00\x009\x00\x008\x00\x005\x00\x00\x16\x00\x00\x13\x00\x00\n\x07\x00\xc0\x00\x003\x00\x002\x00\x00/\x03\x00\x80\x00\x00\x05\x00\x00\x04\x01\x00\x80\x00\x00\x15\x00\x00\x12\x00\x00\t\x06\x00@\x00\x00\x14\x00\x00\x11\x00\x00\x08\x00\x00\x06\x04\x00\x80\x00\x00\x03\x02\x00\x80\x00\x00\xff\x9dd\x83\xbfP\xdb/L\xd6\x88>\xfa\xbbs\x88\xbd\x0cN\xfd\x0f\x84\x8c\xad\x04x61\x99\x82\x01\x19|' | |
| 2011-12-05 18:26:57.973470 : 221.205.139.111:52880 | |
| 2011-12-05 18:26:57.973497 | '\xaa\x14f\x82\x97\xfb\xfc\xab\xf0\xed\xafY\x9e\xd62?[\xf8JU\xf5X\xc1\xfa\x1bZZ\x9a\xe6\xd0FBV\xfb\x9fbG#\xbb\xc2?\x8b\xa2\xe1ZY\xa6h\xee0 \xe9\xea\xd1\xfb\xb9\xe5s\x0c\xb0\xc4\x12BB\xbe%\x93\xb0_\xaf\xca\x97\xd8]\x90\x89\x1b\r\xe8\x11^<\x0bt\x10\xd6\xd8\x9a\xe3\xb0w1\x14\xa0\xb8^MK\x0e\xabz\xd7\xc2\xd1\xb3\xd1Z\xcd\xdd\xc1^<}\xe7/\x8c\xbe\x86\xa6!6\x1d\xd0I=\x08&\x89\xd23\xb4\xcb\x89\xf5\x9c=\xc6\xf6\x89\xa47f_\xb3N\x8d@\x8b\x92e+\xc7\x01\xfa\x8f=\x82\xb5FTg\xf9\x9e\xf0\xee:\xac\xb4\xaf\xb4\xd7\xe6\x1b6\x99hBX\xf2\xd3\xbc\x1d\x1a\xbd\x96)y\x97\xdd\xbej\xc37\x083%B^Yp\x13\xafV\xac\xe5o\x14\'\xc6\x85z\x03!\x93\xbf6\xbb8\xcd\x18v7\xdb\xac\xbe\x8dQ\xff\xeb)\xee\xfd\xd7E\xa9\xbc\xb3<c\xf8@\xdc\xfa\xdfo9\x94+\xf0a\xc1\xe5\x18\x9c\x91\xd5*aT\x94\x89B\x11a\x069\x9c8t\xfe13Z\xaa\x91\xc9c%sS\x064\xb7\x1dPHq\xf8\xa9\xc4\x8c\xb1\x85\x1c\x12\x8bT.\xc2G,ry\x86\x1d\n\xce\xfe\xad\xc0\xd0\xb2s\x87N\xc2N\xbe:\xf6\x02E\xa8\x87`9\x91\xb3fS\xf9\x12E\xf1\x17az\xe4\xde($\xaeY\x965\xa7\xd8\x82\xe4\x12\xf8\xe6\xd6 \xec6X}i>O\xe1O\x93\xd3\xe4s\xcc\xc8Q\xf3\xeb\xfe\xcc\x01\xb2s\xd8\xb4W\xea\xac\xbc@K\xa8\xf4"\xa4]_\xf3\xbe-\x06\x11\x11y\xdcXIP\xc2\xc7\x1c\xc3y\x0e\x1b\xacd\x05X\xa0\xc3\xa2H\xb8Dl\x94\xa2\xdeRO\xe3\xe1\xde\xdb\xbe\xb6%\x8d\xf7k' | |
| 2011-12-05 18:26:58.839414 : 218.10.51.83:1629 | |
| 2011-12-05 18:26:58.839469 | '\xd7s\x10\x05\x95\x86\xe6\x89ok\x07\xd2\x95\xab}\x16\x10\xc4\xc8F\xac|ax\x86d\xc6\x03\x19_=\xd1\x13W\x14\x8dG\x0e;Y.\'\xd2\x90\xa3\xab X\xb1w\x97\xe4e\xd8A=\xc7\xd0\xe4S\xc46\xcb\x86\xea9\x9bIz\xe0\xa8\xe7\xb7\x1b\x8c\xa8H\x1aK\xfdl\t\xdf\xa0\xb4\xd3\xcd\xe8r~\xd5\\u\xfa\xdb\xab\xad\xf5s\'U\x9a\x0e\x0c4\x993|3\xfc\xf8\x1e\x85\xd8\xbd9\xab\n!\x9d\x87vx\xfbp\xd2&\x9c\xc7\x18\xc2\x1c\xb1O\xa6eg\xd8`\x99UX\xb6\xd90s\x12[|\xb2\xf7\x83(\xee~\x17\xc0$\xb2\x87;\xf3"lB\xc7\xd0\xa8\x1f\xaf\xc1s\x07wL\xb6j\xdd\x11e\x8f\x87\xe76u\xe5\xcb5\t};C\xef\\\xae1\xa2\xfdX\xc0\xac\x19\xb33\x90\xfe\xe8y[\xf8]\xe9\xfeE\x9es\xa9i\'\xb1easT<\xa1\x84]\x9e\xdc\x9c\xcatO\xfc\x04\xcdd\xfb(\xdbY\x91\xd9\x1d/L\xc5\x98\xf1\xf5|Rh\xd0\r\t\xd3i\'/\x84p\xa3\xd3l&\xa0\xcf"G*\xf9\xd7\x03\x16\x07\xcdZ\x1e' | |
| 2011-12-05 18:26:59.704311 : 112.94.175.239:35960 | |
| 2011-12-05 18:26:59.704387 | '\xcb\x11E.\xf7I\x91Y\x92{\x00\x0f\xd0&\xc3\x1c\xe1Tq\xe3C\xf9\xd9\xfd\xeb}\x8c\xd2\xfc\xa5\xf9K\x9f\x8c*\x86\xdb\x1f\xe3\x19v\xd951\xb6Ep\xa4\xde\x1cJ\xd1S\x95\',\xa9\xdc\xba\x03y\xc0\xfc\xe7\x9b\x12\x1f\xee\x18k\xa5\xdb75H\xe8\x84\x97+2\xbb\xd1*\xaa\xef\xb1\xb3\t7\xaf4{\xa2\xbf\x05\xac>#\x9aU\x8e\xbe0D\xf3\xf7\xab\xf6\x0e\xd5\xa7H\xa6Pq\x95\x01$\x1d\xb6\xd3P1\xf4\x8e5 \xcbX: ew\xcf\xa8jFS\xdf\xd2\xa7\x86\x1bM\xd5\x0baU/}\x0c\x81L\xbb\xf4\xdap\x14\xa5G\xccE\xabD\x14\xd2-\xd8\xa4\r\xaaK\x12\xc4\x17gOw;}s\xc5\xfd\xbe\x81\xf1\x18p\x84=\xb6Q\x81\xe0\x14\x142@\xeb\xd5\xcb\x95\x9f]\xd95\xc3(+}$\x9dC\xa0\xdaC\x11r\xb2\x94\xae\xe7d/Gw\xc1x7\xac\xcc\x02\xc0k^\x99\x1f\xa0@I\x1ece`\x03?"\x130S\'\xdd:\x8a\x8b\x80\x81Lw\xb7wC88-\x96\xd0K6\x11\x93\xd2\xf2w\xb1\xf55\xd2\x87e%\xadB\xdd8M\xdc8\x98S\xee\x10\x95&G\xc1;\x96\x8bq&\x9d\xc2\x19\x14t\x8dIF\x14\xad\xea\xc1nGx\xba$\xaf\xd2v\x1d\xe1\x8bB\xa7L}\xbcWm\xe2\xf3\xaez\x87"\x86\xcf\xe7\x99\xfbQ\xd9\xe8\x97\xd0\xa3\xba\x7fu\xb0\x9b\xd5;]\xfb\x06Y\xb7\\E\x19\xcf\xf2\x12V\x94\x97\xa4{\xb0\x9f\xcb\t\x87b\xd9\xa9\x9c\xd7\x9dL' | |
| 2011-12-05 18:27:00.785398 : 113.58.246.59:19316 | |
| 2011-12-05 18:27:00.785443 | '\xcb\x11E.\xf7I\x91Y\x92{\x00\x0f\xd0&\xc3\x1c\xe1Tq\xe3C\xf9\xd9\xfd\xeb}\x8c\xd2\xfc\xa5\xf9K\x9f\x8c*\x86\xdb\x1f\xe3\x19v\xd951\xb6Ep\xa4\xde\x1cJ\xd1S\x95\',\xa9\xdc\xba\x03y\xc0\xfc\xe7\x9b\x12\x1f\xee\x18k\xa5\xdb75H\xe8\x84\x97+2\xbb\xd1*\xaa\xef\xb1\xb3\t7\xaf4{\xa2\xbf\x05\xac>#\x9aU\x8e\xbe0D\xf3\xf7\xab\xf6\x0e\xd5\xa7H\xa6Pq\x95\x01$\x1d\xb6\xd3P1\xf4\x8e5 \xcbX: ew\xcf\xa8jFS\xdf\xd2\xa7\x86\x1bM\xd5\x0baU/}\x0c\x81L\xbb\xf4\xdap\x14\xa5G\xccE\xabD\x14\xd2-\xd8\xa4\r\xaaK\x12\xc4\x17gOw;}s\xc5\xfd\xbe\x81\xf1\x18p\x84=\xb6Q\x81\xe0\x14\x142@\xeb\xd5\xcb\x95\x9f]\xd95\xc3(+}$\x9dC\xa0\xdaC\x11r\xb2\x94\xae\xe7d/Gw\xc1x7\xac\xcc\x02\xc0k^\x99\x1f\xa0@I\x1ece`\x03?"\x130S\'\xdd:\x8a\x8b\x80\x81Lw\xb7wC88-\x96\xd0K6\x11\x93\xd2\xf2w\xb1\xf55\xd2\x87e%\xadB\xdd8M\xdc8\x98S\xee\x10\x95&G\xc1;\x96\x8bq&\x9d\xc2\x19\x14t\x8dIF\x14\xad\xea\xc1nGx\xba$\xaf\xd2v\x1d\xe1\x8bB\xa7L}\xbcWm\xe2\xf3\xaez\x87"\x86\xcf\xe7\x99\xfbQ\xd9\xe8\x97\xd0\xa3\xba\x7fu\xb0\x9b\xd5;]\xfb\x06Y\xb7\\E\x19\xcf\xf2\x12V\x94\x97\xa4{\xb0\x9f\xcb\t\x87b\xd9\xa9\x9c\xd7\x9dL' | |
| 2011-12-05 18:30:43.346920 | '\x80w\x01\x03\x01\x00N\x00\x00\x00 \x00\x009\x00\x008\x00\x005\x00\x00\x16\x00\x00\x13\x00\x00\n\x07\x00\xc0\x00\x003\x00\x002\x00\x00/\x03\x00\x80\x00\x00\x05\x00\x00\x04\x01\x00\x80\x00\x00\x15\x00\x00\x12\x00\x00\t\x06\x00@\x00\x00\x14\x00\x00\x11\x00\x00\x08\x00\x00\x06\x04\x00\x80\x00\x00\x03\x02\x00\x80\x00\x00\xff\xcd]\x06\xb5S\xdb\x87\x8e\x06\x1a\x14\xfd\xf0\xd5;\x81\xf6(\xeaB\xb0)(&\x9d\xaf\xcc\xc0g2\x1a\xf4' | |
| 2011-12-05 18:30:46.450253 < 'foo\n' | |
| 2011-12-05 18:30:46.450253 > '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' | |
| 2011-12-05 18:30:56.230631 < 'bar\n' | |
| 2011-12-05 18:30:56.230631 > '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' | |
| 2011-12-05 18:30:57.130697 < 'baz\n' | |
| 2011-12-05 18:30:57.130697 > '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' |
| Tentative Conclusions 08 DEC 2011 | |
| --------------------------------- | |
| Based on the data so far, it appears that all TCP/443 connections out of | |
| China to previously-uncategorized hosts are subject to DPI, and, if an SSL | |
| handshake of any type is detected, subject to active probing. TCP/443 | |
| connections that do not speak obvious SSL (ie obfs2 protocol) do not appear | |
| to be probed. TCP/443 connections to "old" hosts (definition of "old" is | |
| very much unknown at this time) do not appear to cause probing. | |
| SSL connections to other TCP ports, including "SSL-expected" ports like | |
| TCP/993 and TCP/995, do not appear to initiate probing, no matter how | |
| provacative the certificates in use. This is a change from previous | |
| behavior; during investigation of #4185 in October 2011, Tor and other SSL | |
| connections on non-TCP/443 ports were definitely probed (and blocked). It | |
| appears that the GFW's SSL probing has been significantly changed since that | |
| time. Further investigation is still ongoing. | |
| Update 1640 UTC: A non-obfs2 Tor connection to a random high port | |
| (TCP/18457) on a virgin non-published bridge IP resulted in an SSL-connected | |
| scan that appeared to act as a Tor client (not yet confirmed from debug | |
| logs) several minutes after the initial connection was established (and | |
| reconnected several times). More than 10 minutes after the probing, the | |
| bridge IP:PORT had not yet been blocked. | |
| Update 2100 UTC: The full SSL-speaking (and tor-speaking) probes appear to | |
| happen consistently at roughly 15 minute-past-the-hour intervals (:00, :15, | |
| :30, :45). This is consistent to a range of +3 minutes through all of the | |
| samples we've collected so far (with only one outlier in the +3 minute | |
| range, all others within 1 minute of the 15 minute mark). | |
| Thus far we have been unable to provoke this type of probing using anything | |
| other than a full Tor connection. SSL connections to non-Tor servers, even | |
| those using Tor-like SSL certificates, have not been able to trigger it. | |
| The Tor connection does not need to be persistent to trigger the probing; a | |
| short connection just long enough to build a circuit, made only 2-3 minutes | |
| before a "scheduled" scan time, was enough to provoke a scan at the next | |
| interval. A similar duration circuit right after a previous "scheduled" | |
| scan time also provoked a scan at the next interval. | |
| An openssl s_client connection to an actual Tor server did NOT provoke a | |
| scan of this nature. | |
| TCP traceroute to an SSL/Tor-speaking prober during and after a probe does | |
| not yield any change. See traceroute.txt for a sample. Still pending: | |
| using the same sourceport with a handy iptables trick thanks to mikeperry. | |
| 09 DEC 2011 | |
| ----------- | |
| A connection to Tor 0.2.3.8 from a Tor 0.2.3.8 client with the ServerName | |
| SSL extension removed still provoked probing. | |
| A connection to Tor 0.2.3.8 from a Tor 0.2.3.8 client with a reduced SSL | |
| cipher list did NOT provoke probing. Further testing is in progress. | |
| The iptables trick did not work for traceroute with an identical | |
| sourceip:sourceport:destip:destport tuple; my suspicion is that conntrack | |
| gets in the way of the rewriting. Additional data added to traceroute.txt | |
| (see data for 60.13.132.232). | |
| Subsequent tweaking of the iptables trick returned the traceroute data for | |
| 113.58.244.209, which showed no difference between "during probe" and "after | |
| probe" in the short term. | |
| Observations | |
| ------------ | |
| * Probing will re-occur with new connection attempt to a previously probed | |
| (but not blocked) system if repeated after more than 10 minutes. New | |
| connections less than 10 minutes after a previous probe do not generate | |
| new probes, even if the SSL certs exchanged are changed. | |
| * The 10 minute timer appears to start from the time of the final probe in | |
| a sequence, not the first probe. | |
| * Probing occurs within moments of an SSL exchange that contains a | |
| "probable" cert / cert chain within the constraints of the time limit | |
| notes above. | |
| * Several probes are initiated in each instance of probing, from multiple | |
| hosts. | |
| Plans | |
| ----- | |
| * Use cronned */5 TCP ping to each port from inside CN to verify | |
| reachability |
| 2) obfs2 transport (https://gitweb.torproject.org/obfsproxy.git) | |
| ---------------------------------------------------------------- | |
| Initial instance of obfs2 on TCP/443 generated one set of probes that | |
| did not conform to other probe methodologies. No repeats occurred with | |
| over two hours of operation and disconnects/reconnects. | |
| Subsequent use of obfs2 on a new TCP port did not provoke any probing | |
| with over an hour of operation and disconnects/reconnects as well as | |
| (failed, but intended to fail) openssl s_client and wget connection | |
| attempts. | |
| A longer duration obfs2 test back on TCP/443 on a fresh clean IP did not | |
| reveal any probing in over 24 hours of execution. | |
| 3) Tor-like-SSL (control) | |
| ------------------------- | |
| TCP/443: | |
| * hotpot.py: triggers probing, does not cause blockage. | |
| * server.pl: triggers probing, does not cause blockage. | |
| * unpublished tor 0.2.3.8 bridge: openssl s_client triggers probing, no block | |
| * unpublished tor 0.2.3.8 bridge: tor 0.2.3.4-alpha client triggers | |
| probing, no block | |
| * unpublished tor 0.2.3.5 bridge: tor 0.2.3.4-alpha client triggers | |
| probing, no block | |
| * unpublished tor 0.2.3.4 bridge: tor 0.2.3.4-alpha client triggers | |
| probing, no block | |
| * apache-wget: triggers probing, does not cause blockage. | |
| TCP/14392: | |
| * server.pl: no probing | |
| TCP/18457: | |
| * unpublished tor 0.2.3.8 bridge: openssl s_client does not trigger probing | |
| * unpublished tor 0.2.3.8 bridge: tor 0.2.3.4-alpha client triggers real SSL | |
| probing, with several minute delay (probing occurred at ~30 minutes past | |
| the hour) | |
| * The above two tests were performed in close proximity and can't be nailed | |
| down; further testing pending. Bridge IP for this test was 50.17.159.162. | |
| TCP/16415 | |
| * unpublished tor 0.2.3.8 bridge: tor 0.2.3.4-alpha client triggers real SSL | |
| probing 10 minutes after Tor connection established (probing occurred at | |
| ~45 minutes past the hour) | |
| * results replicated again, this time with scanning at :00 past the hour. | |
| 4) Self-signed cert | |
| ------------------- | |
| Certificate: | |
| Data: | |
| Version: 1 (0x0) | |
| Serial Number: | |
| 9f:46:4c:ab:e1:db:41:bb | |
| Signature Algorithm: sha1WithRSAEncryption | |
| Issuer: C=US, ST=Minnesota, L=Duluth, O=Joe Bloggs, LTD, CN=iscream.4dq.com/emailAddress=root@null.com | |
| Validity | |
| Not Before: Dec 7 16:22:02 2011 GMT | |
| Not After : Dec 6 16:22:02 2012 GMT | |
| Subject: C=US, ST=Minnesota, L=Duluth, O=Joe Bloggs, LTD, CN=iscream.4dq.com/emailAddress=root@null.com | |
| Subject Public Key Info: | |
| Public Key Algorithm: rsaEncryption | |
| Public-Key: (4096 bit) | |
| * apache-wget TCP/443: triggers probing | |
| 5) Real CA-issued cert | |
| ---------------------- | |
| Certificate: | |
| Data: | |
| Version: 3 (0x2) | |
| Serial Number: | |
| 0f:5b:4e:f2:f3:68:af:a5:83:a3:37:e1:15:7c:c8:b2 | |
| Signature Algorithm: sha1WithRSAEncryption | |
| Issuer: C=GB, ST=Greater Manchester, L=Salford, O=Comodo CA Limited, CN=PositiveSSL CA | |
| Validity | |
| Not Before: Dec 7 00:00:00 2011 GMT | |
| Not After : Dec 6 23:59:59 2012 GMT | |
| Subject: OU=Domain Control Validated, OU=PositiveSSL, CN=www.joebloggsltd.net | |
| Subject Public Key Info: | |
| Public Key Algorithm: rsaEncryption | |
| Public-Key: (4096 bit) | |
| * apache-wget TCP/443: triggers probing | |
| * apache-firefox TCP/443: triggers probing | |
| * apache-firefox to www.team-cymru.org: does not appear to trigger probing | |
| * apache-wget TCP/14952: no probing | |
| * apache-firefox TCP/14952: no probing | |
| 7) Firewall everybody but the intended user of the bridge. | |
| ---------------------------------------------------------- | |
| Clients in China provided access to a bridge that permitted access only to a | |
| set of explicitly whitelisted IPs were able to access the bridge for >48 | |
| hours without blockage. | |
| 8) Other protocols for reference (ssh, ftp, smtp, smtps) | |
| -------------------------------------------------------- | |
| * POP3S CA-signed cert: no probing | |
| * POP3S self-signed cert: no probing | |
| * POP3S tor-like cert: no probing | |
| 9) TCP connection/scan with no SSL handshake | |
| -------------------------------------------- | |
| hping -S -p 443 <test IP> and telnet <test IP> 443 both failed to generate | |
| scanning to a server which did generate scanning when connected via openssl | |
| s_client. | |
| 13) Relay with debug verbosity after SSL-based probing duplicated | |
| ----------------------------------------------------------------- | |
| Upon analysis of debug logs from a 0.2.3.8-alpha bridge, SSL-based probes | |
| from CN appear to be speaking the Tor protocol, similar to the behavior | |
| of a client with multiple bridges configured that is not actively using | |
| our bridge. |
| 1) Handshakes using OpenSSL and libnss | |
| 2) obfs2 transport (https://gitweb.torproject.org/obfsproxy.git) | |
| 3) Tor-like-SSL (control) | |
| 4) Self-signed cert | |
| 5) Real CA-issued cert | |
| 6) Vary responses of bridge to probing as well as initial handshake (independently if possible) | |
| 7) Firewall everybody but the intended user of the bridge. | |
| 8) Other protocols for reference (ssh, ftp, smtp, smtps) | |
| 9) TCP connection/scan with no SSL handshake | |
| 10) Connection into China-hosted bridge from outside of China, which side (if any) gets probed? | |
| 11) Handshakes using real Apache on the server side | |
| 12) Tor 0.2.1.x stable | |
| 13) Relay with debug verbosity after SSL-based probing duplicated | |
| 14) Determine how many negative probes it takes for the GFW to say "this is | |
| not worth probing anymore" (may prove difficult) |
| Sample traceroute to a prober during a probe: | |
| traceroute -T -O ack --sport=993 -n -p 6885 113.58.244.51 | |
| traceroute to 113.58.244.51 (113.58.244.51), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 0.360 ms 0.314 ms 0.237 ms | |
| 2 10.1.18.13 0.447 ms 0.382 ms 0.389 ms | |
| 3 10.1.19.14 0.460 ms 0.369 ms 0.344 ms | |
| 4 216.182.232.50 0.686 ms 0.674 ms 0.439 ms | |
| 5 72.21.222.148 0.830 ms 0.931 ms 0.742 ms | |
| 6 72.21.220.52 1.152 ms 1.121 ms 1.191 ms | |
| 7 168.143.232.49 1.050 ms 0.921 ms 0.996 ms | |
| 8 129.250.3.118 2.783 ms 2.280 ms 2.733 ms | |
| 9 192.205.37.53 3.535 ms 3.189 ms 3.045 ms | |
| 10 12.122.134.134 76.622 ms 75.564 ms 76.007 ms | |
| 11 12.122.18.21 73.662 ms 71.409 ms 71.971 ms | |
| 12 12.122.31.85 71.701 ms 72.252 ms 71.765 ms | |
| 13 12.122.30.25 77.486 ms 75.511 ms 75.763 ms | |
| 14 12.122.30.30 70.226 ms 72.362 ms 71.562 ms | |
| 15 12.123.30.249 70.481 ms 70.040 ms 70.323 ms | |
| 16 12.122.129.145 73.380 ms 73.415 ms 73.626 ms | |
| 17 12.116.103.6 289.428 ms 289.163 ms 289.259 ms | |
| 18 219.158.4.177 280.133 ms 280.081 ms 279.180 ms | |
| 19 219.158.15.10 285.558 ms 277.110 ms 277.112 ms | |
| 20 219.158.23.242 295.061 ms 295.484 ms 295.082 ms | |
| 21 221.11.155.250 295.448 ms 295.591 ms 295.428 ms | |
| 22 221.11.160.14 298.747 ms 301.180 ms 301.139 ms | |
| 23 * * * | |
| 24 * * * | |
| 25 * * * | |
| 26 * * * | |
| 27 * * * | |
| 28 * * * | |
| 29 *^C | |
| After the probe: | |
| traceroute -T -O ack --sport=993 -n -p 6885 113.58.244.51 | |
| traceroute to 113.58.244.51 (113.58.244.51), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 0.321 ms 0.230 ms 0.268 ms | |
| 2 10.1.18.13 17.777 ms 1.088 ms 0.384 ms | |
| 3 10.1.19.14 0.644 ms 0.541 ms 0.613 ms | |
| 4 216.182.232.50 0.743 ms 0.685 ms 0.745 ms | |
| 5 72.21.222.148 0.953 ms 0.975 ms 0.694 ms | |
| 6 72.21.220.52 1.193 ms 0.999 ms 1.186 ms | |
| 7 168.143.232.49 0.844 ms 1.032 ms 0.947 ms | |
| 8 129.250.3.118 2.337 ms 2.236 ms 2.241 ms | |
| 9 192.205.37.53 3.386 ms 3.232 ms 3.287 ms | |
| 10 12.122.134.134 75.566 ms 75.584 ms 75.913 ms | |
| 11 12.122.18.21 72.999 ms 71.614 ms 72.121 ms | |
| 12 12.122.31.85 72.872 ms 72.201 ms 72.168 ms | |
| 13 12.122.30.25 74.797 ms 76.056 ms 75.605 ms | |
| 14 12.122.30.30 73.746 ms 72.219 ms 71.538 ms | |
| 15 12.123.30.249 70.312 ms 70.102 ms 70.144 ms | |
| 16 12.122.129.145 71.867 ms 72.608 ms 72.667 ms | |
| 17 12.116.103.6 289.208 ms 289.009 ms 289.292 ms | |
| 18 219.158.4.177 280.327 ms 280.069 ms 280.181 ms | |
| 19 219.158.15.10 277.672 ms 277.070 ms 277.369 ms | |
| 20 219.158.23.242 295.198 ms 295.630 ms 295.114 ms | |
| 21 221.11.155.250 296.065 ms 295.571 ms 295.917 ms | |
| 22 221.11.160.14 301.651 ms 301.019 ms 301.074 ms | |
| 23 * 221.11.160.14 299.997 ms 301.065 ms | |
| 24 * * * | |
| 25 * * *^C | |
| Sample using mikeperry's iptables hack to use the same exact TCP tuple as | |
| the live connection, while it was live it failed; pcaps showed that the | |
| packets weren't going out at all, and appeared to be eaten at the iptables | |
| layer. | |
| traceroute -T -O ack --sport=1234 -n -p 15713 60.13.132.232 | |
| traceroute to 60.13.132.232 (60.13.132.232), 30 hops max, 40 byte packets | |
| 1 * * * | |
| 2 * * * | |
| 3 * * * | |
| 4 *^C | |
| But the same ports to a different IP were okay: | |
| traceroute -T -O ack --sport=1234 -n -p 15713 1.2.3.4 | |
| traceroute to 1.2.3.4 (1.2.3.4), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 0.432 ms 0.355 ms 1.001 ms | |
| 2 10.1.16.13 0.593 ms 0.576 ms 0.339 ms | |
| 3 10.1.17.14 0.349 ms 0.425 ms 0.436 ms | |
| 4 216.182.224.82 0.645 ms 0.479 ms 0.436 ms | |
| 5 72.21.222.148 0.691 ms 0.680 ms 0.733 ms | |
| 6 72.21.220.36 40.609 ms 1.297 ms 1.244 ms | |
| 7 168.143.232.73 1.207 ms !N 1.361 ms !N 1.499 ms !N | |
| And after the prober closed its connection: | |
| traceroute -T -O ack --sport=1234 -n -p 15713 60.13.132.232 | |
| traceroute to 60.13.132.232 (60.13.132.232), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 0.328 ms 0.268 ms 0.284 ms | |
| 2 10.1.14.13 0.412 ms 0.520 ms 0.283 ms | |
| 3 10.1.15.14 0.393 ms 0.424 ms 0.441 ms | |
| 4 216.182.224.78 0.497 ms 0.429 ms 0.501 ms | |
| 5 72.21.222.148 0.806 ms 0.728 ms 0.688 ms | |
| 6 72.21.220.68 0.870 ms 0.972 ms 0.931 ms | |
| 7 168.143.191.17 1.439 ms 1.325 ms 1.378 ms | |
| 8 192.205.37.53 3.388 ms 3.271 ms 3.050 ms | |
| 9 12.122.134.134 73.478 ms 71.643 ms 71.718 ms | |
| 10 12.122.18.21 76.272 ms 75.908 ms 78.250 ms | |
| 11 12.122.31.85 74.103 ms 71.976 ms 82.942 ms | |
| 12 12.122.30.25 75.551 ms 74.995 ms 76.269 ms | |
| 13 12.122.30.30 73.357 ms 75.962 ms 75.576 ms | |
| 14 12.123.30.249 73.233 ms 73.750 ms 73.583 ms | |
| 15 12.122.129.49 74.569 ms 74.515 ms 73.608 ms | |
| 16 12.118.130.86 238.895 ms 282.266 ms 252.014 ms | |
| 17 219.158.96.221 240.930 ms 240.885 ms 240.886 ms | |
| 18 219.158.96.225 242.314 ms 242.288 ms 242.288 ms | |
| 19 219.158.23.94 311.817 ms 311.760 ms 311.904 ms | |
| 20 221.7.2.250 314.890 ms 314.793 ms 314.791 ms | |
| 21 221.7.3.26 313.309 ms 313.450 ms 313.255 ms | |
| 22 * * * | |
| 23 * * *^C | |
| Another prober, this time actually during the probing thanks to more | |
| iptables and routing hackery: | |
| traceroute -T -O ack --sport=1234 -n -p 18339 113.58.244.209 | |
| traceroute to 113.58.244.209 (113.58.244.209), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 22.941 ms 4.654 ms 0.896 ms | |
| 2 10.1.14.13 0.308 ms 0.294 ms 0.335 ms | |
| 3 10.1.15.14 0.400 ms 0.446 ms 0.353 ms | |
| 4 216.182.232.50 0.614 ms 0.492 ms 0.457 ms | |
| 5 72.21.222.148 0.657 ms 0.689 ms 0.749 ms | |
| 6 72.21.220.52 1.107 ms 1.243 ms 1.206 ms | |
| 7 168.143.232.49 1.208 ms 1.221 ms 1.207 ms | |
| 8 129.250.3.118 2.107 ms 2.286 ms 2.263 ms | |
| 9 192.205.37.53 11.880 ms 3.407 ms 3.336 ms | |
| 10 12.122.134.134 72.544 ms 71.551 ms 71.749 ms | |
| 11 12.122.18.21 72.905 ms 75.897 ms 75.792 ms | |
| 12 12.122.31.85 77.837 ms 75.563 ms 76.777 ms | |
| 13 12.122.30.25 76.276 ms 75.540 ms 76.331 ms | |
| 14 12.122.30.30 73.454 ms 74.699 ms 71.855 ms | |
| 15 12.123.30.249 74.593 ms 74.357 ms 74.842 ms | |
| 16 12.122.129.145 73.903 ms 69.713 ms 72.209 ms | |
| 17 12.116.103.10 279.680 ms 279.639 ms 279.349 ms | |
| 18 219.158.3.161 266.821 ms 269.409 ms 267.077 ms | |
| 19 219.158.96.54 256.382 ms 254.179 ms 254.349 ms | |
| 20 219.158.14.106 306.252 ms 306.526 ms 306.267 ms | |
| 21 221.11.155.250 305.514 ms 305.254 ms 305.474 ms | |
| 22 221.11.160.14 308.502 ms 310.979 ms 311.144 ms | |
| 23 * * * | |
| 24 * * * | |
| 25 * * * | |
| 26 *^C | |
| And the same prober, > 5 minutes after the probe: | |
| & traceroute -T -O ack --sport=1234 -n -p 18339 113.58.244.209 | |
| traceroute to 113.58.244.209 (113.58.244.209), 30 hops max, 40 byte packets | |
| 1 10.208.200.3 0.439 ms 0.278 ms 0.236 ms | |
| 2 10.1.14.13 5.294 ms 1.225 ms 0.739 ms | |
| 3 10.1.15.14 0.385 ms 0.430 ms 0.442 ms | |
| 4 216.182.232.50 7.351 ms 0.657 ms 0.501 ms | |
| 5 72.21.222.148 0.798 ms 0.719 ms 0.757 ms | |
| 6 72.21.220.52 1.056 ms 1.101 ms 1.108 ms | |
| 7 168.143.232.49 1.062 ms 1.192 ms 1.017 ms | |
| 8 129.250.3.118 2.472 ms 2.231 ms 2.240 ms | |
| 9 192.205.37.53 3.337 ms 3.206 ms 3.288 ms | |
| 10 12.122.134.134 73.007 ms 72.235 ms 71.503 ms | |
| 11 12.122.18.21 75.957 ms 76.638 ms 75.013 ms | |
| 12 12.122.31.85 74.581 ms 76.336 ms 76.061 ms | |
| 13 12.122.30.25 74.598 ms 76.213 ms 75.506 ms | |
| 14 12.122.30.30 72.519 ms 72.265 ms 71.669 ms | |
| 15 12.123.30.249 74.450 ms 74.448 ms 74.605 ms | |
| 16 12.122.129.145 69.584 ms 69.976 ms 69.622 ms | |
| 17 12.116.103.10 279.630 ms 279.473 ms 279.406 ms | |
| 18 219.158.3.161 266.466 ms 266.928 ms 267.200 ms | |
| 19 219.158.96.54 254.338 ms 254.340 ms 254.042 ms | |
| 20 219.158.14.106 306.293 ms 306.199 ms 306.074 ms | |
| 21 221.11.155.250 305.337 ms 305.372 ms 305.138 ms | |
| 22 221.11.160.14 305.191 ms 311.037 ms 312.963 ms | |
| 23 * * * | |
| 24 * * * | |
| 25 * * * | |
| 26 * * * | |
| 27 * * * | |
| 28 * * * | |
| 29 * * * | |
| 30 * * * |
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