4. Application | DNS, TFTP, TLS/SSL, FTP, Gopher, HTTP, IMAP, IRC, NNTP, POP3, SIP, SMTP, SNMP, SSH, TELNET, ECHO, BitTorrent, RTP, PNRP, rlogin, ENRP, … |
---|---|
Routing protocols like BGP, which for a variety of reasons run over TCP, may also be considered part of the application or network layer. | |
3. Transport | TCP, UDP, DCCP, SCTP, IL, RUDP, … |
2. Internet | Routing protocols like OSPF, which run over IP, are also to be considered part of the network layer, as they provide path selection. ICMP and IGMP run over IP and are considered part of the network layer, as they provide control information. |
IP (IPv4, IPv6) | |
ARP and RARP operate underneath IP but above the link layer so they belong somewhere in between. | |
1. Network access | Ethernet, Wi-Fi, token ring, PPP, SLIP, FDDI, ATM, Frame Relay, SMDS, … |
Sep 26, 2007
TCP/IP Protocol
OSI
OSI Model | |||
---|---|---|---|
Data unit | Layer | Function | |
Host layers | Data | 7. Application | Network process to application |
6. Presentation | Data representation and encryption | ||
5. Session | Interhost communication | ||
Segments | 4. Transport | End-to-end connections and reliability (TCP) | |
Media layers | Packets | 3. Network | Path determination and logical addressing (IP) |
Frames | 2. Data link | Physical addressing (MAC & LLC) | |
Bits | 1. Physical | Media, signal and binary transmission |
TCP/IP & Internet
1969 ARPA (Advanced Research Projects Agency) funded a research and development project to create ARPAnet network.
1975 Converted from an experimental network to an operational network.
1983 TCP/IP protocols were adopted as Military Standards (MIL STD)
Internet: MILNET plus ARPAnet
1975 Converted from an experimental network to an operational network.
1983 TCP/IP protocols were adopted as Military Standards (MIL STD)
Internet: MILNET plus ARPAnet
Sep 18, 2007
Convert string to html table
#!/bin/sh
sed -e '/^[A-Za-z0-9]*[^\:]$/{
d
}' < source_file > tmp_file
echo "<table>" > destination_file.html
sed -e '/:/{
s/^/<tr><td>/g
s/\:/<\/td><td>/g
s/$/<\/td><\/tr>/g
}' < tmp_file >> destination_file.html
echo "</table>" >> destination_file.html
sed -e '/^[A-Za-z0-9]*[^\:]$/{
d
}' < source_file > tmp_file
echo "<table>" > destination_file.html
sed -e '/:/{
s/^/<tr><td>/g
s/\:/<\/td><td>/g
s/$/<\/td><\/tr>/g
}' < tmp_file >> destination_file.html
echo "</table>" >> destination_file.html
Sep 14, 2007
Replace file contents by perl
#!/usr/bin/perl -w
# use strict;
sub replace_str($$$)
{
my $line = shift;
my $old_string = shift;
my $new_string = shift;
if($line =~ m/($old_string)/)
{
$line =~ s/$old_string/$new_string/;
}
return $line;
}
open (SOURCE_FILE, "source.txt");
open (DESTINATION_FILE, '>>destination.txt');
while ($line = <source_file>) {
$line = replace_str($line,"2","3");
print DESTINATION_FILE $line;
}
close(SOURCE_FILE);
close (DESTINATION_FILE);
# use strict;
sub replace_str($$$)
{
my $line = shift;
my $old_string = shift;
my $new_string = shift;
if($line =~ m/($old_string)/)
{
$line =~ s/$old_string/$new_string/;
}
return $line;
}
open (SOURCE_FILE, "source.txt");
open (DESTINATION_FILE, '>>destination.txt');
while ($line = <source_file>) {
$line = replace_str($line,"2","3");
print DESTINATION_FILE $line;
}
close(SOURCE_FILE);
close (DESTINATION_FILE);
SED notes
Replace in sed
sed -e '/pattern/{
s/old1/new1/g
s/old2/new2/g
}' < source_file > destination_file
sed -e '/pattern/{
s/old1/new1/g
s/old2/new2/g
}' < source_file > destination_file
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