Notion of the Mind

Checking server’s network switch information

I used tcpdump to get the VLAN information I need especially if I don’t have any knowledge with the switch/vLAN I should use (this normally happens if you’re involved in quite big organization with several integrated teams).  Good thing!

[mmond@contra ~]$ sudo tcpdump -i eth0 -vv -w /tmp/vlaninfo.pcap

[mmond@contra ~]$ sudo tcpdump -r /tmp/vlaninfo.pcap


[mmond@contra ~]$ strings /tmp/vlaninfo.pcap


Or better yet using the link I found recently.

[mmond@contra ~]$ sudo tcpdump -nn -v -i bond0 -s 1500 -c 1 ‘ether[20:2]==0x2000’
tcpdump: listening on bond0, link-type EN10MB (Ethernet), capture size 1500 bytes
12:28:18.670063 CDPv2, ttl: 180s, checksum: 692 (unverified), length 264
Device-ID (0x01), length: 27 bytes: ‘roph1p02bck001(FOC1400P80U)’
Address (0x02), length: 13 bytes: IPv4 (1)
Port-ID (0x03), length: 12 bytes: ‘Ethernet1/15’
Capability (0x04), length: 4 bytes: (0x00000229): Router, L2 Switch, IGMP snooping
Version String (0x05), length: 66 bytes:
Cisco Nexus Operating System (NX-OS) Software, Version 7.0(7)N1(1)
Platform (0x06), length: 13 bytes: ‘N6K-C6001-64P’
Native VLAN ID (0x0a), length: 2 bytes: 51
AVVID trust bitmap (0x12), length: 1 byte: 0x00
AVVID untrusted ports CoS (0x13), length: 1 byte: 0x00
Duplex (0x0b), length: 1 byte: full
MTU (0x11), length: 4 bytes: 1500 bytes
System Name (0x14), length: 14 bytes: ‘roph1p02bck001’
System Object ID (not decoded) (0x15), length: 14 bytes:
0x0000: 060c 2b06 0104 0109 0c03 0103 8a1c
Management Addresses (0x16), length: 13 bytes: IPv4 (1)
Physical Location (0x17), length: 15 bytes: 0x00/ML101-R1.2-U10
1 packets captured
1 packets received by filter
0 packets dropped by kernel


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This entry was posted on 2016-02-06 by in Linux, Technology and tagged , , , , .
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