This appears to be a problem with IPv6 support being required by ufw even when the user doesn't request it. Although IPv6 is enabled by default in hardy, VPS providers do not appear to support it (like vpslink.com, per below - IP addresses changed to protect the innocent). # ufw --version ufw 0.16.2 Copyright (C) 2008 Canonical Ltd. # ufw status Firewall not loaded # ufw enable ERROR: problem running init script # /etc/init.d/ufw force-reload * Stopping firewall: ufw... FATAL: Could not load /lib/modules/2.6.18-ovz028stab039.1-smp/modules.dep: No such file or directory ip6tables v1.3.8: can't initialize ip6tables table `filter': iptables who? (do you need to insmod?) Perhaps ip6tables or your kernel needs to be upgraded. FATAL: Could not load /lib/modules/2.6.18-ovz028stab039.1-smp/modules.dep: No such file or directory ip6tables v1.3.8: can't initialize ip6tables table `filter': iptables who? (do you need to insmod?) Perhaps ip6tables or your kernel needs to be upgraded. FATAL: Could not load /lib/modules/2.6.18-ovz028stab039.1-smp/modules.dep: No such file or directory ip6tables v1.3.8: can't initialize ip6tables table `filter': iptables who? (do you need to insmod?) Perhaps ip6tables or your kernel needs to be upgraded. FATAL: Could not load /lib/modules/2.6.18-ovz028stab039.1-smp/modules.dep: No such file or directory ip6tables v1.3.8: can't initialize ip6tables table `filter': iptables who? (do you need to insmod?) Perhaps ip6tables or your kernel needs to be upgraded. FATAL: Could not load /lib/modules/2.6.18-ovz028stab039.1-smp/modules.dep: No such file or directory ip6tables v1.3.8: can't initialize ip6tables table `filter': iptables who? (do you need to insmod?) Perhaps ip6tables or your kernel needs to be upgraded. ...fail! # iptables -L -n Chain INPUT (policy DROP) target prot opt source destination ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-input all -- 0.0.0.0/0 0.0.0.0/0 Chain FORWARD (policy DROP) target prot opt source destination ufw-before-forward all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-forward all -- 0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (policy ACCEPT) target prot opt source destination ufw-before-output all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-output all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-forward (1 references) target prot opt source destination LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK FORWARD]: ' RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-input (1 references) target prot opt source destination RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:137 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:138 RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:139 RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:445 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:68 LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK INPUT]: ' RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-output (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-forward (1 references) target prot opt source destination ufw-user-forward all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-input (1 references) target prot opt source destination ufw-user-input all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-output (1 references) target prot opt source destination ufw-user-output all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-not-local (0 references) target prot opt source destination Chain ufw-user-forward (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-input (1 references) target prot opt source destination ACCEPT all -- 1.2.3.4 0.0.0.0/0 ACCEPT all -- 1.2.3.5 0.0.0.0/0 ACCEPT all -- 1.2.3.6 0.0.0.0/0 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:53 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-output (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0