Day: June 17, 2020

admin | June 17, 2020

How to figure out switch and port via tcpdump

Okay if you have ever worked in a place where their network was complete choas with no documentation or network maps to help you figure out where something resides.

You can sometimes use tcpdump to help you figure out where the server is sitting by using tcpdump.

Syntax

tcpdump -nn -v -i <NIC_INTERFACE> -s 1500 -c 1 ‘ether[20:2] == 0x2000’

Example:

root@ansible:~ # tcpdump –nn -v –i eth0 -s 1500 -c 1 ‘ether[20:2] == 0x2000’
tcpdump: listening on eth3, link-type EN10MB (Ethernet), capture size 1500 bytes
03:25:22.146564 CDPv2, ttl: 180s, checksum: 692 (unverified), length 370
Device-ID (0x01), length: 11 bytes: ‘switch-sw02‘
Address (0x02), length: 13 bytes: IPv4 (1) 192.168.1.15
Port-ID (0x03), length: 15 bytes: ‘Ethernet0/1‘
Capability (0x04), length: 4 bytes: (0x00000028): L2 Switch, IGMP snooping
Version String (0x05), length: 220 bytes:
Cisco Internetwork Operating System Software
IOS ™ C2950 Software (C2950-I6Q4L2-M), Version 12.1(14)EA1a, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2003 by cisco Systems, Inc.
Compiled Tue 02-Sep-03 03:33 by Nicola tesla
Platform (0x06), length: 18 bytes: ‘cisco WS-C2950T-24’
Protocol-Hello option (0x08), length: 32 bytes:
VTP Management Domain (0x09), length: 6 bytes: ‘ecomrd‘
Duplex (0x0b), length: 1 byte: full
AVVID trust bitmap (0x12), length: 1 byte: 0x00
AVVID untrusted ports CoS (0x13), length: 1 byte: 0x00
1 packets captured
2 packets received by filter
0 packets dropped by kernel

root@ansible:~ #

Written by Nick Tailor

admin June 17, 2020 Linux, Network Stuff2 Comments »

admin | June 17, 2020

How to increase disk size on virtual scsi drive using gpart

1.Login to VMware vSphere Client and shutdown server VM guest.

2.Select VM Guest server and click “Edit virtual machine settings”. Virtual Machine Properties window will appear. Under “Hardware”, click Hard Disk 2 (which is /data partition) and edit provision size to 200 GB as shown in below screenshot.
Power ON VM guest after editing disk size.

vsphere

3.Take VM snapshot of VM guest.

4.Log on to VM Guest using SSH client, like PuTTy, with “root” user.

5.List the SCSI devices using command – cat /proc/scsi/scsi

6.Run following command to see the name of the partition
ls -d /sys/block/sd*/device/scsi_device/* |awk -F ‘[/]’ ‘{print $4,”- SCSI”,$7}’

7.Run following commands to confirm the size of the SCSI disk for which you have increased size in step 4 has been updated by the following steps

1.echo 1 > /sys/class/scsi_device/2\:0\:1\:0/device/rescan

2.fdisk -l | grep Disk

3.df -h

8.Stop cron and services using commands
service crond stop

9.Unmount “/data” partition using command — umount /data
Note: If you observe “Device is busy” error then make sure that your current session is not in /data partition.

10.Perform following steps to grow added disk space of /data partition based on partition type

For GPT partition type

In this case parted -l command will give below for “sdb” disk partition
*****************************************************
Model: VMware Virtual disk (scsi)
Disk /dev/sdb: 215GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 1049kB 215GB 215GB ext4 Linux LVM lvm
*****************************************************