Introduction Product Overview Installation & Use Support & Troubleshooting Links     updated: 6/17/98

Related Topic   ASIP Ports & Firewalls This section discusses ports used by ASIP services, and how port numbers can be used to provide security. What is a port Table of ports numbers used in ASIP [Advanced] What is a port? A port is a number used to uniquely identify a transaction over a network by specifying not only the host, but the application. For example, you may have a single machine running many different IP services, such as Web service (HTTP), mail service (SMTP), LPD, AFP over TCP, and FTP. When clients attempt to connect, they need your IP address, but they also need to indicate what service they want to talk to so that the data can be sent up to the appropriate application. The port number is what uniquely identifies that service on that host. For example, the default port number for SMTP is 25 and the default for HTTP is 80. If a packet comes in to host "asip.company.com" port 80, then the data is transferred to the web server. If the packet is going to port 25, the data is transferred up to the Mail server. Each host can only have one application "listening" on each port. This means that you couldn't have ASIP Web Service and Personal WebSharing both operating on the same machine unless you changed the port number for one of them (Personal Web Sharing 1.5 now gives you the option to change the port number). The port numbers used are often transparent to the end user; the client software will specify the port number. However, sometimes the user can override the defaults. For example, if you changed your Personal Web Sharing control panel so that it was using port 8080, then users could specify that port number in their URL to make a connection to Personal Web Sharing instead of ASIP Web Server. The URL would look like: http://asip.company.com:8080". Firewalls Port numbers are often used to create "Firewalls", which provide security on a network. For example, if you didn't want anyone outside of your intranet to be able to access your web servers, you can set up a firewall which would prohibit any packet destined to port 80 from passing through your routers. Or you might set up a firewall to prevent all packets except those destined to port 25 to pass; this would allow SMTP service for your intranet, but nothing else. Firewalls can also be set up in other ways, such as allowing or refusing access based on network number of the source computer. Port numbers used in ASIP The table below lists the default port numbers used by ASIP services. ASIP Component Protocol Port number ASIP Web & File Service (File) AFP over TCP 548 (Web) HTTP 80 (FTP) FTP 20, 21 (SMB) Windows File Sharing 139 Name Service (Windows) 137 Datagram Service (Windows) 138 Session Service (Windows) 139 ASIP Mail Server SMTP (in) 25 SMTP (out) 25 IMAP (in) 143 IMAP Admin Access (in) 626 POP3 (in) 110 PASS (in) 106 FINGER (in) 79 Notify Mail (out) 79 ASIP Print Server LPR 515