所以, 試著修改一下 pure-ftpd 的程式, 在 rhost 欄位上頭, 只記錄 IP 位址就可以.

diff -Nur src.orig/ftpd.h src/ftpd.h
--- src.orig/ftpd.h	2006-02-15 22:05:54.000000000 +0800
+++ src/ftpd.h	2006-09-12 21:48:00.629546818 +0800
@@ -557,6 +557,7 @@
 #define STORAGE_PORT6(X) (((struct sockaddr_in6 *) &(X))->sin6_port)
 #define STORAGE_SIN_ADDR(X) ((((struct sockaddr_in *) &(X))->sin_addr).s_addr)
 #define STORAGE_SIN_ADDR6(X) ((((struct sockaddr_in6 *) &(X))->sin6_addr).s6_addr)
+#define STORAGE_SIN_ADDR_NF(X) (((struct sockaddr_in *) &(X))->sin_addr)
 #define STORAGE_SIN_ADDR6_NF(X) (((struct sockaddr_in6 *) &(X))->sin6_addr)
 
 #ifdef HAVE_SS_LEN
diff -Nur src.orig/log_pam.c src/log_pam.c
--- src.orig/log_pam.c	2006-06-12 18:44:25.000000000 +0800
+++ src/log_pam.c	2006-09-12 21:48:12.161475481 +0800
@@ -168,16 +168,19 @@
     logfile(LOG_INFO, "PAM_RHOST enabled. Getting the peer address");
     switch (STORAGE_FAMILY(*peer)) {
       case AF_INET:
-        hent = gethostbyaddr(&STORAGE_SIN_ADDR(*peer), sizeof(STORAGE_SIN_ADDR(*peer)), AF_INET);
+        //hent = gethostbyaddr(&STORAGE_SIN_ADDR(*peer), sizeof(STORAGE_SIN_ADDR(*peer)), AF_INET);
+        hent = NULL;
+	host = inet_ntoa(STORAGE_SIN_ADDR_NF(*peer));
 	break;
 	
       case AF_INET6:
+	host = NULL;
         hent = gethostbyaddr(&STORAGE_SIN_ADDR6(*peer), sizeof(STORAGE_SIN_ADDR6(*peer)), AF_INET6);
 	break;
     }
     
     if (!hent)
-      (void)pam_set_item(pamh, PAM_RHOST, NULL);
+      (void)pam_set_item(pamh, PAM_RHOST, host);
     else
       (void)pam_set_item(pamh, PAM_RHOST, hent->h_name);
 #endif
 

這個 patch 可以由這兒抓取: http://www.teatime.com.tw/~tommy/mypatch/pureftpd_pam_ip.patch

經由上頭的 patch 處理後, 就可以在 rhost 上頭記錄 IP 了.