SSH Server Slow/Lagged/Delayed Login Response

This is really something the SSH Server developers should consider. The cause of this annoyance is because of failed DNS lookups on your IP address, which is especially common for many dedicated/col-located servers and also computers on internal NAT/private networks.

The chances are this is the cause of your SSH Slow/Delayed Login problems.

The easy solution to SSH Login Problems

Edit /etc/ssh/sshd_config

Add this line to disable reverse DNS lookups when someone is logging into your SSH Server:

UseDNS no

It would make sense for this option to be disabled by default, especially considering that someone could have a fake or invalid reverse DNS which makes it impossible to find who was really logged in or trying to login.

The SSH daemon should not initially due any reverse DNS or at least allow the login process to continue and try a few more times during the session to find the reverse DNS if it must.

Latest Articles

Apache/Mod_SSL not serving the right/expected certificate?2010-03-09 04:09:36

Create/Enable SSL Certificates for Apache on Linux/Unix Systems eg. Redhat,Centos,Debian2010-03-09 04:07:21

MySQL Error "ERROR 1045 (28000): Access denied for user"2010-03-06 06:35:42

MySQL "Got error 28 from storage engine"2010-03-06 06:32:28

How to Track Down/Find Cause of Linux high disk iowait/wa2010-02-19 01:41:31

Mysqld Solution - Can't init databases /usr/libexec/mysqld: Can't read dir of '/tmp/' (Errcode: 13) /usr/libexec/mysqld: Can't create/write to file '/tmp/ibyP1qUC' (Errcode: 13) 100215 7:02:24 InnoDB: Error: unable to create temporary file; errno:2010-02-15 07:11:17

Windows Vista sysprep.exe /generalize error "The computer restarted unexpectedly or encountered an unexpected error. Windows installation cannot proceed. To install Windows, click "OK" to restart the computer, and then restart the installation."2010-02-13 10:08:29

Openvz "Container already locked" Error Message Solution/Fix2010-02-13 09:44:14

Adventures in pre-paid SIM Cards and data GPRS/Edge/3G in China with China Mobile in Shenzhen, Guangzhou, Shanghai, Beijing and other cities2010-02-12 08:37:57

iPhone Enable Tethering Manually Update ipcc Carrier Settings/Update via SSH2010-02-08 06:03:16

How To Enable 3rd/third party packages in RHEL/Redhat/Centos 4/5 Linux via RPMForge2010-01-17 16:44:41

How to avoid web content hijacking/copying/Force content to be accessed by only 1 domain name2010-01-17 16:39:39

SAMBA/SMB Share "Write" Access without Delete2009-12-19 20:04:22

The power of passive vs air cooling. Small fans make a world of difference.2009-12-18 13:22:52

Hard Drive Not Working/Not Detected By Your BIOS Anymore?2009-12-12 11:29:09

GRUB "Error 2: Bad file or directory type" 0.97 won2009-12-09 21:25:09

Unixbench Score with Glusterfs/Openvz & Quad Core Xeon - Updated with GlusterFS 2.0.8 & Optimized Client Config2009-11-29 01:26:44

Clustered/Distributed Network Filesystems, Which Ones live up to the hype?2009-11-28 22:19:13

Unixbench Score with Glusterfs/Openvz & Quad Core Xeon - Updated with GlusterFS 2.0.82009-11-28 22:04:16

yum error not working rpmdb: mmap: No such device TypeError: rpmdb open failed2009-11-23 00:06:42