While connecting the Linux server through putty, following error occurred. SSHD server unexpectedly closed network connection<\/p>\n
tail -f \/var\/log\/audit\/audit.log<\/p>\n
type=USER_AUTH msg=audit(1292432614.589:14079): user pid=5965 uid=0 auid=0 ses=1 msg=’op=PAM:authentication acct=”user” exe=”\/usr\/sbin\/sshd” hostname=192.168.1.5 addr=192.168.1.5 terminal=ssh res=success’
\ntype=USER_ACCT msg=audit(1292432614.598:14080): user pid=5965 uid=0 auid=0 ses=1 msg=’op=PAM:accounting acct=”user” exe=”\/usr\/sbin\/sshd” hostname=192.168.1.5 addr=192.168.1.5 terminal=ssh res=failed’
\ntype=USER_LOGIN msg=audit(1292432614.600:14081): user pid=5965 uid=0 auid=0 ses=1 msg=’op=login acct=”user” exe=”\/usr\/sbin\/sshd” hostname=? addr=192.168.1.5 terminal=sshd res=failed’<\/p>\n
There may be several reasons for the error. Try the following trouble shoot methods.<\/p>\n
Solution #1<\/b><\/p>\n
Try
\n#touch \/etc\/environment
\ncreates the file<\/p>\n
Solution #2<\/b>
\nCheck \/etc\/hosts.deny file for any ip \/ host blocking.<\/p>\n
Solution #3<\/b><\/p>\n
Check the authentication method, After modifying the pam.d it started working.<\/p>\n
#cd \/etc\/pam.d
\n#vim\u00a0 system-auth-ac<\/b><\/p>\n
auth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_env.so
\nauth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_unix.so nullok try_first_pass
\nauth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 requisite\u00a0\u00a0\u00a0\u00a0 pam_succeed_if.so uid >= 500 quiet
\nauth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_ldap.so use_first_pass
\nauth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_smb_auth.so use_first_pass nolocal
\nauth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_deny.so<\/p>\n
account\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_unix.so broken_shadow
\naccount\u00a0\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_localuser.so
\naccount\u00a0\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_succeed_if.so uid < 500 quiet
\naccount\u00a0\u00a0\u00a0\u00a0 [default=bad success=ok user_unknown=ignore] pam_ldap.so
\naccount\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_permit.so<\/p>\n
password\u00a0\u00a0\u00a0 requisite\u00a0\u00a0\u00a0\u00a0 pam_cracklib.so try_first_pass retry=3
\npassword\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_unix.so sha512 shadow nullok try_first_pass use_authtok
\npassword\u00a0\u00a0\u00a0 sufficient\u00a0\u00a0\u00a0 pam_ldap.so use_authtok
\npassword\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_deny.so<\/p>\n
session\u00a0\u00a0\u00a0\u00a0 optional\u00a0\u00a0\u00a0\u00a0\u00a0 pam_keyinit.so revoke
\nsession\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_limits.so
\nsession\u00a0\u00a0\u00a0\u00a0 [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
\nsession\u00a0\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0\u00a0 pam_unix.so
\nsession\u00a0\u00a0\u00a0\u00a0 optional\u00a0\u00a0\u00a0\u00a0\u00a0 pam_ldap.so<\/p>\n
#vim sshd<\/b><\/p>\n
auth\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 include\u00a0\u00a0\u00a0\u00a0\u00a0 system-auth
\naccount\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0 pam_nologin.so
\naccount\u00a0\u00a0\u00a0 include\u00a0\u00a0\u00a0\u00a0\u00a0 system-auth
\npassword\u00a0\u00a0 include\u00a0\u00a0\u00a0\u00a0\u00a0 system-auth
\n# pam_selinux.so close should be the first session rule
\nsession\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0 pam_selinux.so close
\nsession\u00a0\u00a0\u00a0 include\u00a0\u00a0\u00a0\u00a0\u00a0 system-auth
\nsession\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0 pam_loginuid.so
\n# pam_selinux.so open should only be followed by sessions to be executed in the user context
\nsession\u00a0\u00a0\u00a0 required\u00a0\u00a0\u00a0\u00a0 pam_selinux.so open env_params
\nsession\u00a0\u00a0\u00a0 optional\u00a0\u00a0\u00a0\u00a0 pam_keyinit.so force revoke<\/p>\n","protected":false},"excerpt":{"rendered":"
While connecting the Linux server through putty, following error occurred. SSHD server unexpectedly closed network connection Error log: tail -f \/var\/log\/audit\/audit.log type=USER_AUTH msg=audit(1292432614.589:14079): user pid=5965 uid=0 auid=0 ses=1 msg=’op=PAM:authentication acct=”user”… Read more »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[110],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/posts\/116"}],"collection":[{"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/comments?post=116"}],"version-history":[{"count":5,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/posts\/116\/revisions"}],"predecessor-version":[{"id":741,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/posts\/116\/revisions\/741"}],"wp:attachment":[{"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/media?parent=116"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/categories?post=116"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.melberi.com\/linuxadmin\/wp-json\/wp\/v2\/tags?post=116"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}