Need to monitor Linux server performance?

Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues.
The commands shown below are the basic commands when it comes to system analysis and debugging server issues:

Continue Reading…

Tutorial TCPdump

Valic —  June 28, 2010 — Leave a comment

TCPdump is a very powerful command line interface packetsniffer.

Step 1. Install TCPdump

apt-get install tcpdump

Stept 2. TCPdump use

Step 2.1 To display the Standard TCPdump output:

tcpdump
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
15:14:25.060050 IP 89.35.90.202.clax.ro.27015 > h89-37-110-61.teleson.ro.27005: UDP, length 229
15:14:25.060071 IP 89.35.90.202.clax.ro.27015 > 86-124-241-9.rdsnet.ro.27005: UDP, length 374
15:14:25.060213 IP 86-124-240-65.rdsnet.ro.27005 > 89.35.90.202.clax.ro.27015: UDP, length 78
15:14:25.060236 IP 91-213-135-21.optic-bridge.com.ro.45249 > 89.38.255.34.28822: UDP, length 20
15:14:25.060240 IP 89.35.90.202.clax.ro.27015 > 86-124-240-65.rdsnet.ro.27005: UDP, length 221
15:14:25.060481 IP 89.35.90.202.clax.ro.27015 > 78-21-42-14.access.telenet.be.27005: UDP, length 163
15:14:25.060694 IP 89.35.90.202.clax.ro.27015 > user-ip-23-89-33-89-sel.rdsnav.ro.63087: UDP, length 224
15:14:25.060731 IP 89.35.90.202.clax.ro.32783 > ns1.clax.ro.domain: 65251+ PTR? 61.110.37.89.in-addr.arpa. (43)
15:14:25.060830 IP 89.35.90.202.clax.ro.27015 > 92.83.223.46.61499: UDP, length 113
15:14:25.060851 IP 89.35.90.202.clax.ro.38331 > 89.35.90.18.clax.ro.62613: P 2328008232:2328008428(196) ack 4034406897 win 410
15:14:25.060910 IP 89.35.90.202.clax.ro.27015 > 86-121-72-43.rdsnet.ro.27005: UDP, length 109
15:14:25.060966 IP 92.83.176.255.27005 > 89.35.90.202.clax.ro.27015: UDP, length 74
15:14:25.061020 IP 89.35.90.202.clax.ro.27015 > 95-65-79-185.starnet.md.27005: UDP, length 117

Step 2.2 Network interfaces available for the capture:

Continue Reading…

Page 1 of 11