sudo vi \/etc\/ssh\/sshd_config<\/pre>\nAdd or update the following line:<\/p>\n
UseDNS no<\/pre>\nSave the file and restart the SSH daemon:<\/p>\n
sudo systemctl restart sshd<\/pre>\nB. Verify Hostname Resolution<\/strong><\/h4>\n\n- Ensure the server\u2019s hostname is correctly mapped in
\/etc\/hosts<\/code>:<\/li>\n<\/ul>\n127.0.0.1 localhost\r\n192.168.x.x your-hostname<\/pre>\n2. Check for GSSAPI Authentication Delays<\/strong><\/h3>\nGSSAPI (Kerberos) authentication can slow down SSH login if not configured properly.<\/p>\n
\n- Edit the SSH configuration:<\/li>\n<\/ul>\n
sudo vi \/etc\/ssh\/sshd_config<\/pre>\nDisable GSSAPI-related options:<\/p>\n
GSSAPIAuthentication no\r\nGSSAPICleanupCredentials no<\/pre>\nSave the file and restart SSH:<\/p>\n
sudo systemctl restart sshd<\/pre>\n3. Optimize PAM (Pluggable Authentication Module) Settings<\/strong><\/h3>\nPAM modules, such as delay-inducing password checks or environment setups, can impact login times.<\/p>\n
\n- Review
\/etc\/pam.d\/sshd<\/code> for unnecessary modules.<\/li>\n- Disable or reconfigure any non-essential modules.<\/li>\n<\/ul>\n
4. Check SSH Key Authentication<\/strong><\/h3>\n\n- If you are using key-based authentication:\n
\n- Ensure the private key is not encrypted with a passphrase (or use
ssh-agent<\/code> to cache passphrases).<\/li>\n- Test the key exchange manually for delays:<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
ssh -vvv user@hostname<\/pre>\n5. Inspect SELinux and Firewall<\/strong><\/h3>\nA. SELinux<\/strong><\/h4>\n\n- Ensure SELinux is not causing delays by logging denials:<\/li>\n<\/ul>\n
sudo ausearch -m AVC -ts recent<\/pre>\nIf necessary, temporarily disable SELinux to test:<\/p>\n
sudo setenforce 0<\/pre>\nB. Firewall<\/strong><\/h4>\n\n- Check if firewalld or iptables rules are delaying connections:<\/li>\n<\/ul>\n
sudo firewall-cmd --list-all<\/pre>\n6. Analyze System Logs<\/strong><\/h3>\n\n- Inspect
\/var\/log\/secure<\/code> or \/var\/log\/messages<\/code> for SSH-related errors or delays:<\/li>\n<\/ul>\nsudo tail -f \/var\/log\/secure\r\nsudo tail -f \/var\/log\/messages<\/pre>\n7. Test Network Latency<\/strong><\/h3>\n\n- Ensure network latency is not the root cause<\/li>\n<\/ul>\n
ping -c 4 <client-ip>\r\ntraceroute <client-ip><\/pre>\n8. Miscellaneous Configurations<\/strong><\/h3>\n\n- Increase SSH logging for debugging:<\/li>\n<\/ul>\n
sudo vi \/etc\/ssh\/sshd_config<\/pre>\nLogLevel DEBUG<\/p>\n
Restart SSH:<\/p>\n
sudo systemctl restart sshd<\/pre>\nIf NTP synchronization issues exist, correct the time settings:<\/p>\n
sudo timedatectl set-ntp true<\/pre>\n9. Final Optimization<\/strong><\/h3>\n\n- Ensure the SSH server is running the latest version:<\/li>\n<\/ul>\n
sudo yum update -y openssh-server<\/pre>\nConsider optimizing sshd<\/code> configurations further based on system requirements:<\/p>\nClientAliveInterval 30\r\nClientAliveCountMax 3<\/pre>\nBy systematically addressing these factors, you can resolve ssh login slow issues on RHEL7.<\/p>\n","protected":false},"excerpt":{"rendered":"
Here in this post you can find a simple solution to fix SSH login slow. Slow SSH login on RHEL7 can be caused by various factors, including DNS resolution, reverse lookups, PAM configurations, or network latency. Here’s a step-by-step guide to troubleshoot and resolve the issue: Steps to fix ssh login slow: 1. Check DNS […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,10,1,11],"tags":[74,36,75],"class_list":["post-670","post","type-post","status-publish","format-standard","hentry","category-control-panel","category-general","category-linux","category-security","tag-dns","tag-firewall","tag-ssh"],"_links":{"self":[{"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/posts\/670","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/comments?post=670"}],"version-history":[{"count":10,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/posts\/670\/revisions"}],"predecessor-version":[{"id":680,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/posts\/670\/revisions\/680"}],"wp:attachment":[{"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/media?parent=670"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/categories?post=670"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/249host.com\/tutorials\/wp-json\/wp\/v2\/tags?post=670"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}