Delay on initial access server ftp, http and telnet, etc - NOT usual reverse dns problem

Delay on initial access server ftp, http and telnet, etc - NOT usual reverse dns problem

Post by Walt » Mon, 15 Apr 2002 14:37:34

I'm going to be a bit wordy here, because this is truly weird.

My understanding is that if there is no reverse DNS lookup for
something, and reverse dns lookups are on for a server in general,
there's a big delay while things time out.

If that's the case (there's no DNS entry for the client, as might be
the case on a LAN) then you whack the client into the hosts file, and
make sure that the search order is "hosts, then dns" so that it's
found there and things proceed apace, thusly, without DNS ever being

XXX.XXX.XXX.XXX    domain.sfx yadda

I've got a situation where I've got a host elsewhere on our ISP's DSL
network, not on our LAN (it was on our LAN, but it's been moved...
worked great on our lan with nothing but the appropriate hosts
entries). In the server machine's etc/hosts file, is our WAN IP, in
the form shown above. Likewise, on my machine, I've got that server's
IP and domain name in my local hosts file (win98). I can see the
lookup of the remote server happen instantly - explorer reports it is
attempting to connect to the right IP, there's no delay. The delay
appears to be at the other end.

The search order on the remote server machine is hosts, then dns.

Yet, when I try to get to it, there is a huge delay initially, such
that telnet and ftp will time out, but a couple of attempts with http
to the root domain will, eventually, get the web index page. Once
that's done, telnet and ftp run fine, as does http. fast connections,
no timeouts. If you leave them alone for a while, no activity on any
service, the delay returns, as if there's something being cached
somewhere on the server that lets the incoming machine (me) access
stuff, then being expired. As far as I know, there's no local DNS
running on the machine - it uses our ISP's dns. There is a hardware
firewall in a router between the remote server and the WAN, but it is
set to pass all the appropriate ports, and it knows about the ISP's
DNS as well.

Now, I should add that I'm hitting this machine from a win98 system,
but as I understand it, it all works the same (it certainly seemed to
work fine when we had the machine on our LAN!)

Also, the machine I'm on does have a "real" dns entry out on the WAN,
maintained by our ISP - I only put us in the hosts file on the remote
server because the delay was driving me up a wall, and I thought the
DNS lookup was just slow - that wasn't it, though, because it's STILL
piggy as heck.

Running Red hat 6 for the server.

Anyone? Any ideas? I'm getting a headache... :(

Software Engineer
Black Belt Systems


1. reverse-dns. telnet works, ftp does not


I've been fighting with my machine for about a year now =)  If I telnet to it,
it gets right in.  If I ftp to the machine, it sits for a little while before
letting me in (reverse-dnsing, then sometimes timing out).

The box serves as a firewall, and a DNS.  Why would telnet work, but ftp fail
(the reverse-lookup part)?

Could it be something to do with my firewall? (iptables)  If so, what should I
be looking for.  I have 53 open for DNS queries, and the telnet and ftp ports
as well.

| Dave Marotti                | Looking for a Visio alternative for *nix?    |
| lndshark ! speakeasy net    | Kivio : |
| I just don't trust anything | I suppose that in a few more hours I will    |
| that bleeds for 5 days and  | sober up. That's such a sad thought. I think |
| doesn't die. - Mr. Garrison | I'll have a few more drinks to prepare myself|

2. Printer setup problem

3. Initial Delay in telnet/ftp prompts through ethernet

4. crash bug ?

5. Can ping, but not ftp/telnet/http etc.

6. C.C.Li []

7. Need help with DNS -> ftp,telnet,etc not using

8. How to Get Mach64 card working in XWindows ?

9. Please Help - Connection Delay Times With Telnet /HTTP /FTP

10. LAN issue -- login delay TELNET/POP/FTP/ETC

11. SLIP under NET-2: I can ping server, but not telnet/ftp/etc.

12. RH 7.1 Reverse DNS not using /etc/hosts

13. WIERD - Telnet: 75 second delays getting login and output; ftp not operable