Author: J. Patrick Narkinsky
Email: patrick@narkinsky.ml.org
Web Page: http://www.narkinsky.ml.org/
Date Submitted: Mon, Oct 12, 1998
Status: New Entry
Requester: Chris
Email: theking@seanet.com
Request Made: Tue, Apr 21, 1998
Releases: | all |
Platform: | all |
Category: | Networking and netcfg |
Category Listing: | FTP, HTTP, and Telnet are all slow immeiately after initial connection. |
I just Installed linux Redhat 4.2 Full Install 450 megs. What would cause the FTP server, Httpd, and Telnet Servers to have SLOW responce time when tring to login.? Sometimes it will take 5 mins before I even get a User Input responce, Ie. User Name, Password. The Httpd Server dose the same thing. Telnet Server Just sits there and looks dumb. Thanks for the help. Email to: theking@seanet.com
Almost invariably, the type of problems you describe are the result of an incomplete/incorrect reverse DNS setup. In other words, the machine which is trying to connect to you does not have a reverse DNS entry (or possibly has a reverse DNS entry and does not have a matching forward entry). I would recommend two possible solutions for this: first, try getting reverse DNS entries setup for the machines in question. Failing this, add entries for the machines you will be telnetting from to the /etc/hosts file. Most programs will use this file as an alternative to DNS. DNS is an internet protocol/database which allows the host names with which we are all familiar to be converted to IP addresses. Unfortunately, because of the structure of DNS it is impossible to use a single entry to the DNS for both forward (that is I have a hostname and need an IP address) and reverse (I have an IP address and want the hostname) entries. So, every properly configured machine on the internet should have two DNS: one for forward lookups and one for reverse. Very often, network managers are lazy and either do not setup reverse entries at all or only set them up for servers. THIS IS TOTALLY BOGUS AND INCORRECT AND WILL CAUSE ALL KINDS OF PROBLEMS. ALL INTERNET CONNECTED MACHINES SHOULD HAVE MATCHING FORWARD AND REVERSE DNS ENTRIES. Most Linux networking programs (including all of the three you mentioned) attempt to get a hostname for a machine when it connects. If this machine does not have a reverse DNS entry (or possible an entry in /etc/hosts) then this query will have to time out before the application can continue. Typically the timeout can take 30-60 seconds, and will result in exactly the kind of "slow connect performance" problem you are describing. Short form: make sure all your machines have reverse DNS entries.
Man: named /usr/doc/HOWTO/DNS-HOWTO