# iptables -A PREROUTING -t mangle -i eth4 -j CONNMARK --restore-mark iptables: No chain/target/match by that name What's missing ? I do HAVE the module libipt_CONNMARK.so which also strace confirms. The following output makes me think, perhaps I have to activate something in the /proc filesystem !? open("/usr/local/lib/iptables/libipt_CONNMARK.so", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\200\4\0"..., 1024) = 1024 fstat64(3, {st_mode=S_IFREG|0755, st_size=5016, ...}) = 0 old_mmap(NULL, 7480, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0xb7fe9000 mprotect(0xb7fea000, 3384, PROT_NONE) = 0 old_mmap(0xb7fea000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0xb7fea000 close(3) = 0 socket(PF_INET, SOCK_RAW, IPPROTO_RAW) = 3 getsockopt(3, SOL_IP, 0x40 /* IP_??? */, "mangle\0\301\304e9\300\0\0\0\0\0\0\0\0\1\0\0\0004B\23\300"..., [84]) = 0 brk(0) = 0x8055000 brk(0x8056000) = 0x8056000 getsockopt(3, SOL_IP, 0x41 /* IP_??? */, "mangle\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., [2456]) = 0 setsockopt(3, SOL_IP, 0x40 /* IP_??? */, "mangle\0\267RK\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 2668) = -1 ENOENT (No such file or directory) write(2, "iptables: No chain/target/match "..., 45) = 45