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VDI-Tech-Guy merged 2 commits into from
Mar 10, 2026
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tcpdump nni switch #265

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tcpdump nni switch
j-hammer Mar 10, 2026
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Merge branch 'develop' into jhart-adc-updates
VDI-Tech-Guy Mar 10, 2026
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54 changes: 27 additions & 27 deletions docs/class7/modules/module06.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@ Troubleshoot using TCPDump or Curl
a. First let’s see what if we are hitting the virtual server. At the
Linux CLI prompt:

i. **tcpdump -i client_vlan -X -s 128 'host 10.1.10.100 and port 80'**
i. **tcpdump -nni client_vlan -X -s 128 'host 10.1.10.100 and port 80'**

* This is a little overkill, but a good example of syntax. We
will only look at traffic headed for the virtual server, we
Expand Down Expand Up @@ -89,35 +89,35 @@ Troubleshoot using TCPDump or Curl
3. In the second SSH window we will do an expanded **tcpdump** for the
sake of interest.

a. **tcpdump -i server_vlan -X -s 128 'host 10.1.10.6'**
a. **tcpdump –nni server_vlan -X –s 128 'host 10.1.10.6'**

b. Hit your virtual server again. You see packets with your client IP heading for the servers. They just aren’t responding. So we could reasonably suspect a server issue.

.. code::

19:23:24.394987 IP d95aecf4-7016-4b32-b8db-65d7f7af42d8.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994478442 ecr 0], length 0
0x0000: 4500 003c 846e 4000 ff06 c539 0a01 0a06 E..<.n@....9....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 896a 0000 0000 ....;F.j....
19:23:25.394816 IP d95aecf4-7016-4b32-b8db-65d7f7af42d8.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994479442 ecr 0], length 0
0x0000: 4500 003c 8473 4000 ff06 c534 0a01 0a06 E..<.s@....4....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 8d52 0000 0000 ....;F.R....
19:23:26.394885 IP d95aecf4-7016-4b32-b8db-65d7f7af42d8.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994480442 ecr 0], length 0
0x0000: 4500 003c 8477 4000 ff06 c530 0a01 0a06 E..<.w@....0....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 913a 0000 0000 ....;F.:....
19:23:27.394897 IP d95aecf4-7016-4b32-b8db-65d7f7af42d8.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,sackOK,eol], length 0
0x0000: 4500 0030 847c 4000 ff06 c537 0a01 0a06 E..0.|@....7....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: 7002 3908 3236 0000 0204 05b4 0402 0000 p.9.26..........
19:23:28.394998 IP d95aecf4-7016-4b32-b8db-65d7f7af42d8.59358 > 10.1.20.12.http: Flags [R.], seq 792828690, ack 0, win 0, length 0
0x0000: 4500 0028 8480 4000 ff06 c53b 0a01 0a06 E..(..@....;....
0x0010: 0a01 140c e7de 0050 2f41 9b12 0000 0000 .......P/A......
0x0020: 5014 0000 322e 0000 P...2...
.. code::

19:23:24.394987 IP 10.1.10.659358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994478442 ecr 0], length 0
0x0000: 4500 003c 846e 4000 ff06 c539 0a01 0a06 E..<.n@....9....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 896a 0000 0000 ....;F.j....
19:23:25.394816 IP 10.1.10.6.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994479442 ecr 0], length 0
0x0000: 4500 003c 8473 4000 ff06 c534 0a01 0a06 E..<.s@....4....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 8d52 0000 0000 ....;F.R....
19:23:26.394885 IP 10.1.10.6.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,nop,wscale 0,sackOK,TS val 994480442 ecr 0], length 0
0x0000: 4500 003c 8477 4000 ff06 c530 0a01 0a06 E..<.w@....0....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: a002 3908 3242 0000 0204 05b4 0103 0300 ..9.2B..........
0x0030: 0402 080a 3b46 913a 0000 0000 ....;F.:....
19:23:27.394897 IP 10.1.10.6.59358 > 10.1.20.12.http: Flags [S], seq 792828689, win 14600, options [mss 1460,sackOK,eol], length 0
0x0000: 4500 0030 847c 4000 ff06 c537 0a01 0a06 E..0.|@....7....
0x0010: 0a01 140c e7de 0050 2f41 9b11 0000 0000 .......P/A......
0x0020: 7002 3908 3236 0000 0204 05b4 0402 0000 p.9.26..........
19:23:28.394998 IP 10.1.10.6.59358 > 10.1.20.12.http: Flags [R.], seq 792828690, ack 0, win 0, length 0
0x0000: 4500 0028 8480 4000 ff06 c53b 0a01 0a06 E..(..@....;....
0x0010: 0a01 140c e7de 0050 2f41 9b12 0000 0000 .......P/A......
0x0020: 5014 0000 322e 0000 P...2...


4. First, let’s check to see if the server is responding to HTTP on port 80. On the BIG-IP in an SSH window:
Expand Down
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