diff -ruN busybox-1.3.1-old/networking/httpd.c busybox-1.3.1/networking/httpd.c
--- busybox-1.3.1-old/networking/httpd.c	2006-12-27 05:52:39.000000000 +0100
+++ busybox-1.3.1/networking/httpd.c	2006-12-28 18:04:53.000000000 +0100
@@ -137,6 +137,7 @@
 	const char *query;
 
 	USE_FEATURE_HTTPD_CGI(char *referer;)
+	USE_FEATURE_HTTPD_CGI(char *user_agent;)
 
 	const char *configFile;
 
@@ -1062,6 +1063,7 @@
 		putenv("SERVER_PROTOCOL=HTTP/1.0");
 		putenv("GATEWAY_INTERFACE=CGI/1.1");
 		setenv1("REMOTE_ADDR", config->rmt_ip_str);
+		setenv1("HTTP_USER_AGENT", config->user_agent);
 #if ENABLE_FEATURE_HTTPD_SET_REMOTE_PORT_TO_ENV
 		setenv_long("REMOTE_PORT", config->port);
 #endif
@@ -1605,6 +1607,8 @@
 					content_type = strdup(skip_whitespace(buf + sizeof("Content-Type:")-1));
 				} else if ((STRNCASECMP(buf, "Referer:") == 0)) {
 					config->referer = strdup(skip_whitespace(buf + sizeof("Referer:")-1));
+				} else if ((STRNCASECMP(buf, "User-Agent:") == 0)) {
+					config->user_agent = strdup(skip_whitespace(buf + sizeof("User-Agent:")-1));
 				}
 #endif