"Linux Advanced Programming" (13th) Linux Socket Network Programming Fundamentals 4

Network Debugging Tools Tcpdump

function : Print header information in the specified network interface that matches the Boolean expression

Key Words :

① Type: Host (default), NET, port

210.27. 48.2  // indicates that it is a host computer 202.0. 0.0       // indicates that a network  at                 // indicate port number

② confirm Transmission direction: SRC, DST, DST or SRC, DST and SRC

210.27. 48.2    // the source address in the IP packet is this value 202.0. 0.0  // Destination network address is 202.0.0.0

③ protocol Keywords: FDDI, IP, ARP, RARP, TCP, UDP default: All

④ Other Keywords: gateway, broadcast, less, greater

logical Operation : Non (' not ' or '! (' and ' or ' && '), or (' or ' or ' | | '), ）

Note that the parentheses in the command line use ' \ (' and ' \ ')

// Intercept host 210.27.48.1 and host 210.27.48.2 or 210.27.48.3 communication 210.27. 48.1 and \ (210.27.  48.2210.27. 48.3 \)

Common Options :

Netstat

Features: Displays active TCP connections, ports that are monitored by the computer, Ethernet statistics, IP routing tables, IPV4 statistics, and IPV6 statistics when no parameters are present

netstat [-a] [-e] [-n] [-O] [-P Protocol] [-R] [-S] [Interval]

1. Output content Analysis

2. Application examples

-e-S-5-N Co

3. Common parameters

Lsof

#查看/etc//etc/passwd-[email protected] Address

1. Output format

"Linux Advanced Programming" (13th) Linux Socket Network Programming Fundamentals 4