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Have cheep noname "managed" websmart switch, generic china. It have default IP 192.168.1.199 When ping it on LAN with my favorit ping program https://github.com/dexit/fping-windows (using it for years as a windows built-in program print wrong ping statistics when "Destination host unreachable" msg receive), it print no response (tried both TCP and ICMP). When tried windows built-in ping, it print strange text enclosed by parenthesis never seen before, windows 10-19044/ 64bit

Reply from 192.168.1.199: bytes=52 (sent 32) time=1ms TTL=64

compare with ping google DNS server

Reply from 8.8.8.8: bytes=32 time=1ms TTL=57

Have doubts about switch ICMP implementation and plan to report it to vendor as a bug, but not sure. Anyone have idea what this (sent 32) means?

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  • It means 32 bytes were sent but the response had 52. I recommend you take a look at the ICMP traffic using Wireshark.
    – Daniel B
    Commented Oct 6, 2022 at 12:43
  • I have already recorded ICMP communication in wireshark format, but do not understand it. If someone want to look at it, its here: github.com/dexit/fping-windows/files/9723032/icmp.zip Commented Oct 6, 2022 at 17:09

1 Answer 1

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Well, being a noname “smart” switch makes it hazardous software waste I guess! I think the ping routine may be sending out stuff it should not, most likely freed/uninitialized memory.

When you ping, the request contains some random data. The response is supposed to contain the same data. In this case however, there is some trailing garbage.

The request body (random data):

Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000  F0 68 C5 0E 03 E9 58 53 7D E0 83 E5 D1 06 EA 66  ðhÅ..éXS}àƒåÑ.êf
00000010  67 34 D1 9D 3F 78 DF 24 D8 68 22 60 50 B6 54 B6  g4Ñ.?xß$Øh"`P¶T¶

The response body:

Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000  F0 68 C5 0E 03 E9 58 53 7D E0 83 E5 D1 06 EA 66  ðhÅ..éXS}àƒåÑ.êf
00000010  67 34 D1 9D 3F 78 DF 24 D8 68 22 60 50 B6 54 B6  g4Ñ.?xß$Øh"`P¶T¶
00000020  A3 C7 63 74 69 6F 6E 3A 20 63 6C 6F 73 65 0D 0A  £Çction: close..
00000030  43 6F 6E 74                                      Cont

Note the “ction: close”. That’s a fragment of a HTTP header, “Connection: close”. It should not be there. The “Cont” thing is almost certainly also an HTTP header.

Windows appears to be more liberal with interpreting ping responses, not requiring the exact same data back. Or maybe it only compares the 32 bytes it sent, which are the same. The sequence number is okay, too. fping is apparently more strict.

In the end, there is nothing you can do. The switch software is broken and you will probably never get an update.

If you’re interested in hacking, this looks like a fun thing to explore. You could try hitting the web interface while pinging to see if the trailing garbage changes or something.

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