The Ident Protocol is designed to work as a server daemon, on a user's computer, where it receives requests to a specified TCP port, generally 113.
Host B would then issue a response, identifying the user ("stjohns" in this example) who owns the program that initiated this connection and the name of its local operating system: But if it would turn out that no such connection exists on host B, it would instead issue an error response: All ident messages should be delimited by an end of line sequence consisting of the carriage return and linefeed characters (CR+LF).
[1] Dialup hosts or shared shell servers often provide ident to enable abuse to be tracked back to specific users.
A generally accepted solution to this is to set up a generic/generated identifier, returning node information or even gibberish (from the requesters point of view) rather than usernames.
On most IRC networks, when the server fails to get an Ident response, it falls back to the username given by client, but marks it as "not verified", usually by prefixing with a tilde; e.g., ~josh.