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Hi there I'm having a time reader device connect to the network which works fine unless for specific IP addresses it doen't alow telnet but it still relply to the ping. The out put shows my laptop IP address 10.6.80.135 and the problem is with IP address 10.6.80.120

While the IP address 10.6.80.83 is working fine.

78  22.937534000    10.6.80.135 10.6.5.118  TCP 54  49439 > http [RST, ACK] Seq=1 Ack=1 Win=0 Len=0
83  23.578853000    10.6.80.135 10.6.80.120 TCP 66  49443 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1
86  24.092328000    10.6.80.120 10.6.80.135 TCP 60  http > 49443 [RST, ACK] Seq=1 Ack=1 Win=0 Len=0

asked 03 Feb '14, 00:46

sharif's gravatar image

sharif
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accept rate: 0%

edited 03 Feb '14, 02:22

grahamb's gravatar image

grahamb ♦
19.8k330206


Sounds like there is either no telnet server running (or it is listening on a different port) or there is a filter (ACL) that blocks connection requests to the telnet port.

Do you see a SYN-ACK in the capture file?

Regards
Kurt

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answered 03 Feb '14, 01:05

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
24.8k1039237
accept rate: 15%

edited 03 Feb '14, 01:06

In fact it does telnet but when you change the IP address

78 22.937534000 10.6.80.135 10.6.5.118 TCP 54 49439 > http [RST, ACK] Seq=1 Ack=1 Win=0 Len=0 
83 23.578853000 10.6.80.135 10.6.80.120 TCP 66 49443 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1 
86 24.092328000 10.6.80.120 10.6.80.135 TCP 60 http > 49443 [RST, ACK] Seq=1 Ack=1 Win=0 Len=0
(03 Feb '14, 02:01) sharif

Two things

  • you are talking about telnet, but the capture shows http as destination port!?!
  • if you get a RESET (frame 86) after a SYN (frame 83), there is either no server software listening on that port (most likely), or there is a filter on the system (ACL, Firewall) that blocks the connection.

OR

  • there is another system on the network with the same IP. Please check if the MAC address for 10.6.80.120 makes sense (in the capture file), meaning if it is really the MAC address of the device.
(03 Feb '14, 02:08) Kurt Knochner ♦

Yes I'm trying to telnet port 80

(03 Feb '14, 02:48) sharif

O.K. see my comment above, regarding the three possible problems.

(03 Feb '14, 07:16) Kurt Knochner ♦
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question asked: 03 Feb '14, 00:46

question was seen: 2,047 times

last updated: 03 Feb '14, 07:16

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