BCCS199_Session_12 Flashcards
Linux sets up a “conversation” between a local process and…?
a remote server, called a TCP/IP socket.
Like everything else in Linux, a socket is treated as a file which can be…?
written to and read from.
A program uses the same system functions to communicate with a socket as with an…?
ordinary file. The details of how the communication is done are handled at a much lower level.
An application such as a web browser can hold many…?
conversations at once with different (or the same) servers.
Different conversations are identified by…?
different IP addresses and/or port numbers.
In HTTP, a server always receives data on port 80. each separate client conversation, however, has a…?
unique randomly-generated port number which the server uses to send data to that client.
Different protocols use…?
unique port numbers.
Ports less than 1024 are called privileged ports, and are…?
handled especially by the kernel. This helps to ensure that, for example, all HTTP traffic (port 80) is managed by the kernel and not some “rouge” malware.
Find your ip address like this…?
hostname -I
Find the listening ports this way…?
Netstat -tuna | grep “LISTEN”
Internet email is handled by two applications…?
Mail Transfer Agent (MTA).
- A “push” protocol; sends email via SMTP (port 25).
- Sends mail via MTA’s on different servers through the Internet, much like a network of post offices.
Mail User Agent (MUA).
- A “pull” protocol; receives email via POP (port 110) or IMAP (port 143).
- Receives email from MTA; delivers to final recipient on request.
The mail command line application has been around since…?
early Unix days.
It provides a basic email service without the….?
frills, bells and whistles or the massive overhead of a GUI.
/sbin/ifconfig displays…?
local IP configuration.
ping confirms..?
low level network connectivity between hosts.
