Port 113 is often left visible by firewalls since 113 is the IDENT port.

IDENT is used when you connect to mail servers, or to IRC servers, to find out "who" is using the service. With IDENT filtered, your ISP mail server (unlikely) or IRC server (likely) may refuse your request or take a long time to respond as it waits for a closed/open response.

It is possible to remove IDENTD as showing up as a port by reconfiguring your firewall to over-ride the default rules. As above, if IDENTD is filtered in this way, IRC and mail servers may not work properly.

You can also decide that IDENTD is safe, since just having it visible does not mean there is anything that can be exploited on your side, and live with the less than "perfect" results.

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by KeysCapt
last modified: 2004-02-01 05:50:18