2006隨手札記

System Performance and Security

*即時監看log
#tail -f /var/log/[logfile]

*查看網路狀態
＃netstat -tupln
-n : do not resolve IP address to host name
-t : list TCP connections
-u : list UDP connections
-p : show PID and name of the program
-l : listening sockets
-a : --all (non-listening sockets)

*檢查 Ports
#nmap -sS -sU -sR -P0 -A -v stationX
-sS : SYN(chronous) scan
-sU: UDP scan
-sR: RPC/pormap scan
-P0: ping system before scanning
-A : sytem and service version detection
-v : verbose

[root@server1 ~]# nmap -sS -sU -P0 -sR -A -v localhost

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2009-08-03 00:08 CST
Initiating SYN Stealth Scan against localhost.localdomain (127.0.0.1) [1680 ports] at 00:08
Discovered open port 53/tcp on 127.0.0.1
---略---
Discovered open port 995/tcp on 127.0.0.1
The SYN Stealth Scan took 0.32s to scan 1680 total ports.
Initiating UDP Scan against localhost.localdomain (127.0.0.1) [1487 ports] at 00:08
The UDP Scan took 1.46s to scan 1487 total ports.
Initiating service scan against 27 services on localhost.localdomain (127.0.0.1) at 00:08
Discovered open port 53/udp on 127.0.0.1
---略---
Discovered open|filtered port 32772/udp on localhost.localdomain (127.0.0.1) is actually open
The service scan took 76.07s to scan 27 services on 1 host.
Initiating RPCGrind Scan against localhost.localdomain (127.0.0.1) at 00:09
The RPCGrind Scan took 0.04s to scan 6 ports on localhost.localdomain (127.0.0.1).
For OSScan assuming port 21 is open, 1 is closed, and neither are firewalled
For OSScan assuming port 21 is open, 1 is closed, and neither are firewalled
For OSScan assuming port 21 is open, 1 is closed, and neither are firewalled
Host localhost.localdomain (127.0.0.1) appears to be up ... good.
Interesting ports on localhost.localdomain (127.0.0.1):
Not shown: 3140 closed ports
PORT STATE SERVICE VERSION
21/tcp open ftp vsftpd 2.0.5
22/tcp open ssh OpenSSH 4.3 (protocol 2.0)
25/tcp open smtp Sendmail 8.13.8/8.13.8
53/tcp open domain ISC Bind 4.X
---略---

* 檢查file system
#df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
5.1G 1.5G 3.4G 31% /
/dev/xvda2 1.9G 36M 1.8G 2% /home
/dev/xvda1 99M 13M 81M 14% /boot
tmpfs 129M 0 129M 0% /dev/shm

[root@server118 ~]# du -sh /tmp
32K /tmp
[root@server118 ~]#

*搜尋檔案
#find / \( -nouser -o -nogroup \)

*monitor processes
#top