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alaskanjackal
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Topic Author
Posts: 25
Joined: Tue Sep 29, 2015 1:29 pm

traceroute when 5+ consecutive hops timeout

Thu Feb 22, 2018 10:40 pm

One of my Mikrotiks is behind an ISP that hides all of its routers from traceroutes from devices on their network (stupid, but whatever). Since there are six hops between that device and the ISP's upstream (the first place that responds to ICMP pings) and the Mikoritik /tool traceroute tool will automatically stop probing after five consecutive timeouts, this has the effect of making it impossible for me to ever trace a route from this router to anywhere on the WAN.

Sample from the device in question outbound:
[admin@ANC] > /tool traceroute use-dns=yes count=10 8.8.8.8
 # ADDRESS                          LOSS SENT    LAST     AVG    BEST   WORST STD-DEV STATUS
 1                                  100%   10 timeout
 2                                  100%   10 timeout
 3                                  100%   10 timeout
 4                                  100%   10 timeout
 5                                  100%   10 timeout

[admin@ANC] >
To illustrate what's going on, here's a traceroute from me at my current location to the device in question:
[admin@SGF] > /tool traceroute use-dns=yes [redacted] count=10
 # ADDRESS                          LOSS SENT    LAST     AVG    BEST   WORST STD-DEV STATUS
 1 100.64.103.1                       0%   10   0.4ms     0.8     0.4     3.8       1
 2 38.131.218.241                     0%   10   0.2ms     0.2     0.2     0.3       0
 3 38.65.114.217                      0%   10   2.7ms     2.7     2.7     2.7       0
 4 v320.core1.mci3.he.net             0%   10   9.1ms      13     9.1    19.7     4.6
 5 100ge12-1.core1.den1.he.net        0%   10  30.8ms    31.7    21.3    58.3    12.2
 6 100ge10-2.core1.slc1.he.net        0%   10  74.2ms    43.1    32.7    74.2    12.5
 7 100ge11-2.core1.pdx1.he.net        0%   10  51.7ms    50.6    49.1    60.8     3.5
 8 gci2.nwax.net                      0%   10  49.4ms    49.5    49.3    49.9     0.2
 9 10.128.4.157                      40%   10 timeout    49.7    49.4    50.3     0.3
10 10.128.4.166                      40%   10 timeout    73.8    73.3    75.5     0.8
11 10.128.240.17                     40%   10 timeout    73.8    73.3    75.2     0.6
12 10.128.4.130                      30%   10 timeout    88.5    88.4    88.7     0.1
13 10.128.8.57                       30%   10 timeout    91.2    90.8    92.2     0.4
14                                  100%   10 timeout
15 x-x-x-x.gci.net             0%   10  98.8ms    99.9    98.7   101.1     0.8

[admin@SGF] >
As you can see, hops 9-14 are either private IPs or nonresponsive. It's those six hops that don't appear at all when tracing outbound from on GCI's network. (I've also tried with protocol=udp and it's the same, so that's not a solution.)

I don't have access to a computer behind that router at the moment, but tracing from Windows or Unix works fine--there are six nonresponsive hops and then the 7th hop and beyond work fine.

So my question is: is there a way to force the Mikrotik to continue past five nonresponsive traceroute hops? Maybe playing with the TTL or something?

Thanks.
Last edited by alaskanjackal on Fri Feb 23, 2018 6:41 pm, edited 1 time in total.
 
BRMateus2
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Frequent Visitor
Posts: 70
Joined: Thu Oct 26, 2017 11:18 pm

Re: traceroute when 5+ consecutive hops timeout

Fri Feb 23, 2018 7:06 am

You can make an firewall rule which catches those packets from your IP to ISP LAN and redirects to your own router. I didn't knew the traceroute stops after 5 failures.

Edit actually my mikrotik traceroute doesn't stop after 5 timeouts.
 
alaskanjackal
newbie
Topic Author
Posts: 25
Joined: Tue Sep 29, 2015 1:29 pm

Re: traceroute when 5+ consecutive hops timeout

Fri Feb 23, 2018 7:12 pm

You can make an firewall rule which catches those packets from your IP to ISP LAN and redirects to your own router. I didn't knew the traceroute stops after 5 failures.

Thanks. OK, so going with the nugget I gleaned from your advice, I set up a Mangle rule on the Output chain to change the TTL of anything less than 5 to a new TTL of 5. I tested it on my device here and it had the intended effect of making my first four hops all the same as my fifth hop.

I then deployed the same rule on the device in Anchorage and it didn't work. I found I had to increase the TTL all the way to 9 to get any results. Apparently GCI, the ISP, hides even more of its network from the inside interface than I thought--the first hop I was able to get to respond was all the way in Seattle (1,500 miles away, at the internet exchange there). They started doing that a couple years ago for completely unknown reasons but since I usually trace routes from a Windows or Linux machine and not from the Mikrotik itself, it never affected me (beyond it being a minor annoyance to wait while those hops failed to respond):

[admin@ANC] > /tool traceroute use-dns=yes count=10 8.8.8.8
 # ADDRESS                          LOSS SENT    LAST     AVG    BEST   WORST STD-DEV STATUS
 1 google.nwax.net                    0%   10  55.1ms    56.5    54.3    69.5     4.4
 2 google.nwax.net                    0%   10    55ms    55.7    53.7      61       2
 3 google.nwax.net                    0%   10    57ms    56.5      54      66     3.9
 4 google.nwax.net                    0%   10    55ms    54.9      54      56     0.7
 5 google.nwax.net                    0%   10    55ms    56.3      54      62     2.3
 6 google.nwax.net                    0%   10  54.4ms    55.3    54.1    60.4     1.8
 7 google.nwax.net                    0%   10  54.5ms      55    54.4    55.9     0.5
 8 google.nwax.net                    0%   10  54.5ms    55.7    54.4    58.6     1.2
 9 google.nwax.net                    0%   10  54.9ms    54.9    54.3    55.7     0.4
10 108.170.245.113                    0%   10  54.9ms      55    53.9    56.2     0.6
11 108.170.231.27                     0%   10  55.3ms    56.5    54.4    68.4       4
12 google-public-dns-a.google.com     0%   10  54.7ms    56.1      54    62.6     2.4

[admin@ANC] > /tool traceroute use-dns=yes count=10 206.81.93.33
 # ADDRESS                          LOSS SENT    LAST     AVG    BEST   WORST STD-DEV STATUS
 1 12.122.158.182                     0%   10  89.2ms    82.2    79.1    89.2     2.6
 2 12.122.158.182                     0%   10  83.2ms    81.9    79.1    87.5     2.6
 3 12.122.158.182                     0%   10  80.1ms    80.8    79.3    83.9     1.4
 4 12.122.158.182                     0%   10  79.7ms    80.4    79.6    83.3       1
 5 12.122.158.182                     0%   10  79.9ms    80.5    79.2    87.6     2.4
 6 12.122.158.182                     0%   10  80.4ms    80.8    79.7    83.9     1.5
 7 12.122.158.182                     0%   10  79.3ms    80.9    79.3    84.2     1.8
 8 12.122.158.182                     0%   10  88.2ms    81.8    79.7    88.2     2.6
 9 12.122.158.182                     0%   10  80.3ms    81.9    79.4    95.7     4.8
10 12.122.158.157                     0%   10  79.1ms    79.3    78.9    80.4     0.4
11 12.117.205.66                      0%   10  85.6ms    80.8    79.4    85.6     1.7
12 ip-206-81-93-33.astac.net          0%   10 109.3ms   102.3    99.9   109.3     2.9

[admin@ANC] >

Anyway, it works, so I was able to diagnose the path I was looking at. (I needed to see if that second test above, to the ASTAC address, was staying local to Alaska or routing from Anchorage to Seattle and back--it's the latter.) Thanks.

Edit actually my mikrotik traceroute doesn't stop after 5 timeouts.

I thought maybe it's just the fact that the first five were timeouts but I was able to sort of recreate it here:
[admin@SGF] > /tool traceroute use-dns=yes protocol=udp count=10 [redacted]
 # ADDRESS                          LOSS SENT    LAST     AVG    BEST   WORST STD-DEV STATUS
 1 100.64.103.1                       0%   10   0.4ms     1.9     0.4     5.2     1.9
 2 38.131.218.241                     0%   10   0.2ms     0.2     0.2     0.3       0
 3 38.65.114.217                      0%   10   2.7ms     2.7     2.7     2.8       0
 4 v320.core1.mci3.he.net             0%   10     9ms    11.4       9    21.1     4.6
 5 100ge12-1.core1.den1.he.net        0%   10  21.5ms    21.4    21.3    21.5     0.1
 6 100ge10-2.core1.slc1.he.net        0%   10    40ms      38    32.7    42.7     4.4
 7 100ge11-2.core1.pdx1.he.net        0%   10  49.9ms    57.7    49.1      88    12.1
 8 gci1.nwax.net                      0%   10  49.5ms    49.5    49.3    49.9     0.2
 9 10.128.4.157                      10%   10 timeout    49.5    49.3    50.1     0.2
10 10.128.4.166                      30%   10 timeout    73.7    73.4    74.7     0.4
11 10.128.240.17                      0%   10  73.4ms    73.4    73.3    73.6     0.1
12 10.128.4.130                       0%   10  88.4ms    88.5    88.4    88.6     0.1
13 10.128.8.57                        0%   10  90.9ms      91    90.8    91.1     0.1
14                                  100%   10 timeout
15                                  100%   10 timeout
16                                  100%   10 timeout
17                                  100%   10 timeout
18                                  100%   10 timeout

[admin@MikroTik] >
I don't have the far-end device set to respond to UDP pings, so it effectively serves as a nonresponsive device, and it causes the same behavior--and you can see it times out after five nonresponsive hops, even if they're at the end of the traceroute. I'm running 6.41.1.

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