Telnet response time slow after SonicWALL installation (992 Views)
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Occasional Advisor
Just Guessing
Posts: 17
Registered: ‎11-17-2005
Message 1 of 12 (992 Views)

Telnet response time slow after SonicWALL installation

I repoaced a Linksys business router with a SonicWALL TZ 215 on my network.  All is well except for my HP UX server.  Users telnet into the HP via ProComm.  The login takes as much as 45 seconds to appear and will often fail.  This is peer to peer traffic via an IP address - not a name - so I know it's not DNS related.

 

I have factory reset the SonicWALL and only conifgured Internet access.  No firewall.  No filtering.  SonicWALL support says it's my network not the SonicWALL.  He says telnet fails at the application level - which means switches.  I do have switches and I have eliminated them by connecting the HP and a laptop directly into the SonicWALL - I have the same problem.

 

I have even tried a crossover cable directly to the HP box via a laptop and I still get this slow response.

 

I have replaced my main roeuter in the past with no problems.  What could be the issue with the SonicWALL - or is this an entirely different issue?

 

Thanks! 

Honored Contributor
Patrick Wallek
Posts: 13,787
Registered: ‎06-21-2000
Message 2 of 12 (988 Views)

Re: Telnet response time slow after SonicWALL installation

I assume the long login time start after the SonicWall was installed?

 

Is there any way to take the SonicWall appliance out of the picture?  Is it possible to connect the HP-UX server and a PC to some sort of switch so they don't go through the SonicWall?

 

If you can do that, and the performance improves, then you have your culprit.  However, if it is still slow, then you have other issues.

Occasional Advisor
Just Guessing
Posts: 17
Registered: ‎11-17-2005
Message 3 of 12 (985 Views)

Re: Telnet response time slow after SonicWALL installation

When I remove the SonicWALL all is well. When I run a crossover cable from my laptop to the HP UX I get a slow login. Everything is fine with my Linksys router connected. But there is no configuration on the Linksys router in connnection with the HP.
Honored Contributor
Laurent Menase
Posts: 1,079
Registered: ‎11-06-2003
Message 4 of 12 (979 Views)

Re: Telnet response time slow after SonicWALL installation

[ Edited ]

Looks like dns problem,

 

typically telnet is slow when dns is not responding.

so try a nslookup ipaddrofthepc

 

Else only tusc may help you to identify what telnetd is doing ( attached to inetd )

 

 and may be a network trace taken on hpux ( nettl -tn all -e all -f somefile ; reproduce; nettl -tf -e all ) then read the file with wireshark.

 

Other common cause for such symptoms: duplicate IP, router not answering to ping done by the dead gateway detection, ....

 

Occasional Advisor
Just Guessing
Posts: 17
Registered: ‎11-17-2005
Message 5 of 12 (966 Views)

Re: Telnet response time slow after SonicWALL installation

But I'm using an IP address to Telnet.  I would think DNS is out of the picture.

Honored Contributor
Matti_Kurkela
Posts: 6,271
Registered: ‎12-02-2001
Message 6 of 12 (962 Views)

Re: Telnet response time slow after SonicWALL installation

The HP-UX system may be trying to do a reverse DNS lookup on the incoming connection, to map a source IP address into a DNS name in order to log where the incoming connection is coming from.

 

Another possibility is identd: the HP-UX system may be trying to contact the source host and query its identd for the username associated with the connection. (This is especially likely if you have tcpwrappers installed and configured in a certain way.) If there is no firewall and the source host has no identd running (e.g. because it's a Windows workstation), the HP-UX system would normally receive a TCP Reset from the source host, which would be a clue that identd is not available. Then the login would proceed normally with an imperceptibly short delay.

 

But with a firewall, an unexpected connection to the identd port is likely to be dropped, causing no response to the identd request at all. An identd request is a TCP connection, so it would observe the normal TCP timeouts. It follows that if the HP-UX systems leaves an incoming telnet connection hanging while it waits for response for its identd connection, by the time the identd connection times out, the telnet connection is close to timing out too.

 

(I once had this exact problem with a FTP service in an old HP-UX, maybe version 11.00 or 10.20. The FTP daemon insisted on making ident queries and I could not find a way to disable that feature at that time.)

 

Most firewalls are set up to DROP (i.e. ignore without any response at all) any connections that are not listed as allowed in the firewall rules. But for the specific case of the ident protocol (port 113/TCP), it might be beneficial to set up a REJECT rule instead (i.e. for a TCP connection, send a TCP Reset packet back to the source of the connection; for anything else, use an appropriate ICMP error packet to inform the source that the requested service is not available). If you're afraid that someone will use the REJECT rule as a vector for a denial-of-service attack, you can combine the REJECT rule with a rate-limiter rule, so that the first few connections per second will be rejected as normal, and any more will be dropped without a response.

MK
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Dennis Handly
Posts: 25,287
Registered: ‎03-06-2006
Message 7 of 12 (957 Views)

Re: Telnet response time slow after SonicWALL installation

>When I run a crossover cable from my laptop to the HP-UX I get a slow login.

 

Then how is SonicWALL involved?

Occasional Advisor
Just Guessing
Posts: 17
Registered: ‎11-17-2005
Message 8 of 12 (944 Views)

Re: Telnet response time slow after SonicWALL installation

The problem goes away when I connect the old Linksys router.  The problem comes back when I install the SonicWALL.  Even though I haven't configured it.  It's pretty frustrating.  I've replaced the router a couple of times before without a hitch.  It may have nothing to do with the SonicWALL, but it the symptom occurs when the SonicWALL is connected - or when I connect directly to the HP UX system with a crossover or simple switch.  It doesn't make any sense to me, either.

Honored Contributor
Steven Schweda
Posts: 9,096
Registered: ‎02-23-2005
Message 9 of 12 (938 Views)

Re: Telnet response time slow after SonicWALL installation

Occasional Advisor
Just Guessing
Posts: 17
Registered: ‎11-17-2005
Message 10 of 12 (904 Views)

Re: Telnet response time slow after SonicWALL installation

I have to admit I'm more of a Windows guy.  What commands can I use at the telnet prompt that will give me my HP's network info - especially the DNS server setting.  I put in a new DNS server last month.  Possibly this is an issue?

 

When I do an nslookup with the HP's IP address, I get a "non-existent domain" error.  I looked in my DNS server and I see no listing for the HP server.  But I doubt I had one in my old DNS server, either.

 

Thanks again.

Honored Contributor
Steven Schweda
Posts: 9,096
Registered: ‎02-23-2005
Message 11 of 12 (901 Views)

Re: Telnet response time slow after SonicWALL installation

Honored Contributor
Laurent Menase
Posts: 1,079
Registered: ‎11-06-2003
Message 12 of 12 (885 Views)

Re: Telnet response time slow after SonicWALL installation

to check if it is a dns problem in nsswitch.conf remove dns

#
# /etc/nsswitch.files:
#
# @(#)
#
# An example file that could be copied over to /etc/nsswitch.conf; it
# does not use any name services.
#
passwd:       files
group:        files
hosts:        files
ipnodes:      files
services:     files
networks:     files
protocols:    files
rpc:          files
publickey:    files
netgroup:     files
automount:    files
aliases:      files

 

else next step use tusc -f  -T "" on inetd, then reproduce,

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