fix search domain

src/network/tun_linux.rs

@@ -951,6 +951,7 @@ pub fn modify_resolv_conf(new_nameservers: &[String], search_domain: &str, keep_
     for ns in new_nameservers {
         lines.push(format!("nameserver {}", ns))
     }
+    lines.push(format!("search {}", search_domain));
     /* 
     let mut inserted = false;
     let mut encounted_nameserver = false;