Bug 49687

Summary: 'ReverseMappingCheck' do not work and try to resolve PTR recode when to log in with ssh/slogin
Product: [Retired] Red Hat Linux Reporter: Need Real Name <omori>
Component: opensshAssignee: Tomas Mraz <tmraz>
Status: CLOSED CURRENTRELEASE QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 7.1   
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2005-02-03 09:47:33 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Need Real Name 2001-07-23 10:08:49 UTC 
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux 2.2.18-0vl4.2 i686; ja-JP; 0.7)
Gecko/20010125

Description of problem:
It was very slow when first log in to a linux box with ssh.

How reproducible:
Always

Steps to Reproduce:
It was very slow when first log in to a linux box with ssh.

# tcpdump -evvn -i eth1 '(not port ssh)'

told me the machine tried to look up PTR recode like this:


19:08:06.111363 > 0:0:0:0:0:0 **:**:**:**:**:** ip 85: 192.168.1.11.32768 >
210.188.241.66.domain: 12855+ PTR? 20.1.168.192.in-addr.arpa. (43) (DF)
(ttl 64, id 50829)
19:08:06.131363 < **:**:**:**:**:** 0:0:0:0:0:1 ip 147:
210.188.241.66.domain > 192.168.1.11.32768: 12855 NXDomain q:
20.1.168.192.in-addr.arpa. 0/1/0 (105) (ttl 52, id 57226)

I tried to disable reverse mapping check explicitly with the following command:

# perl -i.bak -pe 's@^#ReverseMappingCheck yes$@ReverseMappingCheck no@'
/etc/ssh/sshd_config

but it found out meaningless. The same packet was sent...


Expected Results:  No reverse mapping check.

Additional info:
Comment 1 Tomas Mraz 2005-02-03 09:47:33 UTC 
There is now UseDNS option (openssh-3.9p1 in current Fedora Core).

If it still fails, reopen the bug report.