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:
There is now UseDNS option (openssh-3.9p1 in current Fedora Core). If it still fails, reopen the bug report.