When using sshd's -i option with stdio that is not a AF_INET/AF_INET6 socket, auth_get_canonical_hostname() returns "UNKNOWN" which is then set as the value of PAM_RHOST, causing pam to try to do a reverse DNS query of "UNKNOWN", which times out multiple times, causing a substantial slowdown when logging in. To fix this, let's only set PAM_RHOST if the hostname is not "UNKNOWN". --- auth-pam.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/auth-pam.c b/auth-pam.c index b49d415e7..706b02420 100644 --- a/auth-pam.c +++ b/auth-pam.c @@ -735,7 +735,7 @@ sshpam_init(struct ssh *ssh, Authctxt *authctxt) sshpam_laddr = get_local_ipaddr( ssh_packet_get_connection_in(s sh)); } - if (sshpam_rhost != NULL) { + if (sshpam_rhost != NULL && strcmp(sshpam_rhost, "UNKNOWN") != 0) { debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, sshpam_rhost); -- 2.43.0 _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev