RHEL5.4IPOPS and IMAPS server configuration details

This section describes the simple configuration of pop3 and ipops servers and the use of packet capture tools in Linux. domestic users generally prefer to use the pop3 protocol to receive emails, which is very insecure, this section also describes the configuration of the ipops server. in the production environment, to configure the ipop3 server, you must sign the certificate in pem format to the CA to be trusted and used by other users. pop3, the imap protocol uses TCP ports 110 and 143 by default, And the ipops and imaps protocols use TCP ports 993 and 9 by default.

This section describes the simple configuration of pop3 and ipops servers and the use of packet capture tools in Linux. domestic users generally prefer to use the pop3 protocol to receive emails, which is very insecure, this section also describes the configuration of the ipops server. in the production environment, to configure the ipop3 server, you must sign the certificate in pem format to the CA to be trusted and used by other users. pop3, by default, the imap protocol uses TCP ports 110 and 143, while the ipops and imaps protocols use TCP ports 993 and 995 by default. The account used by the mail service is a system account, so security is very important, this is also the focus of RHCE...

[Root @ server ~] # Yum-y install dovecot. i386 // install the dovecot package, start the service, set the next time you enable automatic start, view the port
[Root @ server ~] # Service dovecot start
Starting Dovecot Imap: [OK]
[Root @ server ~] # Chkconfig dovecot on
[Root @ server ~] # Netstat-ntpl | grep-E '2017 | 110 | 143 | 993 +'
Tcp 0 0: 993: * LISTEN 4652/dovecot
Tcp 0 0: 995: * LISTEN 4652/dovecot
Tcp 0 0: 110: * LISTEN 4652/dovecot
Tcp 0 0: 143: * LISTEN 4652/dovecot

[Root @ server ~] # Useradd test // create a new system account for testing
[Root @ server ~] # Echo "test" | passwd -- stdin test
Changing password for user test.
Passwd: all authentication tokens updated successfully.

[Root @ server ~] # Yum-y install wireshark. i386 // install the packet capture tool wireshark

[Root @ server ~] # Ifconfig eth1 | grep 'inet addr '// view the local IP Address
Inet addr: 192.168.100.254 Bcast: 192.168.100.255 Mask: 255.255.255.0

[Root @ client ~] # Nmap 192.168.100.254 // use nmap on the client to scan the port opened on the server

Starting Nmap 4.11 (http://www.insecure.org/nmap/) at 2010-03-24 EDT
Interesting ports on 192.168.100.254:
Not shown: 1667 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
53/tcp open domain
110/tcp open pop3
111/tcp open rpcbind
143/tcp open imap
763/tcp open cycleserv
784/tcp open unknown
796/tcp open unknown
993/tcp open imaps
995/tcp open pop3s
2049/tcp open nfs
MAC Address: 00: 0C: 29: 0C: 7C: 4E (VMware)

Nmap finished: 1 IP address (1 host up) scanned in 23.250 seconds

[Root @ client ~] # Telnet 192.168.100.254 110 // The client uses telnet to log on to the POP3 server
Trying 192.168.100.254...
Connected to 192.168.100.254 (192.168.100.254 ).
Escape character is '^]'.
+ OK Dovecot ready.
User test
+ OK
Pass test
+ OK Logged in.
Quit
+ OK Logging out.
Connection closed by foreign host.