bin/62139: User cannot login through telnet or ssh because of reverse resolving delay

[Rostislav Krasny]

>Number:         62139
>Category:       bin
>Synopsis:       User cannot login through telnet or ssh because of reverse resolving delay
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jan 30 19:00:37 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Rostislav Krasny
>Release:        5.2-RELEASE and 5.2-CURRENT
>Organization:
>Environment:
FreeBSD localhost 5.2-CURRENT FreeBSD 5.2-CURRENT #0: Thu Jan 29 13:03:29 IST 2004     root at localhost:/usr/obj/usr/src/sys/GENERIC  i386 
>Description:
When a user tries to login to the system remoutly (by telnet or ssh) the system is trying to reverse resolve its IP address. Because the system does this resolving synchronously the login process delays. When recorded in the /etc/resolv.conf address of single DNS server is unreachable the delay will be very long and it will produce login timeout. It can made this system inaccessible for remote administration through telnet and ssh.
>How-To-Repeat:
To reproduce this problem write non-existent IP address of your subnet as the address of single DNS server in /etc/resolv.conf file. Then try to login to this system remoutly from somewhere. There should be no previously openned connections from the second system.
>Fix:
To fix this problem you can either disable the reverse resolving or do it asynchronously.
>Release-Note:
>Audit-Trail:
>Unformatted: