Add tcpoptions to ipfw. This works much in the same way as ipoptions do.
It also squashes 99% of packet kiddie synflood orgies. For example, to rate syn packets without MSS, ipfw pipe 10 config 56Kbit/s queue 10Packets ipfw add pipe 10 tcp from any to any in setup tcpoptions !mss Submitted by: Richard A. Steenbergen <ras@e-gerbil.net>
This commit is contained in:
dan
parent
c5a16b5d15
commit
9214e704a3
@ -650,6 +650,25 @@ The supported IP options are:
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The absence of a particular option may be denoted
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with a
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.Ql ! .
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.It Cm tcpoptions Ar spec
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Match if the TCP header contains the comma separated list of
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options specified in
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.Ar spec .
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The supported TCP options are:
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.Pp
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.Cm mss
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(maximum segment size),
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.Cm window
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(tcp window advertisement),
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.Cm sack
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(selective ack),
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.Cm ts
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(rfc1323 timestamp) and
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.Cm cc
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(rfc1644 t/tcp connection count).
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The absence of a particular option may be denoted
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with a
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.Ql ! .
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.It Cm established
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TCP packets only.
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Match packets that have the RST or ACK bits set.
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@ -437,7 +437,7 @@ show_ipfw(struct ip_fw *chain, int pcwidth, int bcwidth)
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#define PRINTFLG(x) {if (_flg_printed) printf(",");\
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printf(x); _flg_printed = 1;}
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printf(" tcpflg ");
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printf(" tcpflags ");
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if (chain->fw_tcpf & IP_FW_TCPF_FIN) PRINTFLG("fin");
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if (chain->fw_tcpnf & IP_FW_TCPF_FIN) PRINTFLG("!fin");
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if (chain->fw_tcpf & IP_FW_TCPF_SYN) PRINTFLG("syn");
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@ -451,6 +451,24 @@ show_ipfw(struct ip_fw *chain, int pcwidth, int bcwidth)
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if (chain->fw_tcpf & IP_FW_TCPF_URG) PRINTFLG("urg");
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if (chain->fw_tcpnf & IP_FW_TCPF_URG) PRINTFLG("!urg");
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}
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if (chain->fw_tcpopt || chain->fw_tcpnopt) {
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int _opt_printed = 0;
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#define PRINTTOPT(x) {if (_opt_printed) printf(",");\
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printf(x); _opt_printed = 1;}
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printf(" tcpoptions ");
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if (chain->fw_tcpopt & IP_FW_TCPOPT_MSS) PRINTTOPT("mss");
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if (chain->fw_tcpnopt & IP_FW_TCPOPT_MSS) PRINTTOPT("!mss");
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if (chain->fw_tcpopt & IP_FW_TCPOPT_WINDOW) PRINTTOPT("window");
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if (chain->fw_tcpnopt & IP_FW_TCPOPT_WINDOW) PRINTTOPT("!window");
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if (chain->fw_tcpopt & IP_FW_TCPOPT_SACK) PRINTTOPT("sack");
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if (chain->fw_tcpnopt & IP_FW_TCPOPT_SACK) PRINTTOPT("!sack");
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if (chain->fw_tcpopt & IP_FW_TCPOPT_TS) PRINTTOPT("ts");
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if (chain->fw_tcpnopt & IP_FW_TCPOPT_TS) PRINTTOPT("!ts");
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if (chain->fw_tcpopt & IP_FW_TCPOPT_CC) PRINTTOPT("cc");
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if (chain->fw_tcpnopt & IP_FW_TCPOPT_CC) PRINTTOPT("!cc");
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}
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if (chain->fw_flg & IP_FW_F_ICMPBIT) {
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int type_index;
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int first = 1;
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@ -818,6 +836,7 @@ show_usage(const char *fmt, ...)
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" {established|setup}\n"
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" tcpflags [!]{syn|fin|rst|ack|psh|urg},...\n"
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" ipoptions [!]{ssrr|lsrr|rr|ts},...\n"
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" tcpoptions [!]{mss|window|sack|ts|cc},...\n"
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" icmptypes {type[,type]}...\n"
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" pipeconfig:\n"
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" {bw|bandwidth} <number>{bit/s|Kbit/s|Mbit/s|Bytes/s|KBytes/s|MBytes/s}\n"
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@ -1025,9 +1044,7 @@ fill_port(cnt, ptr, off, arg)
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}
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static void
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fill_tcpflag(set, reset, vp)
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u_char *set, *reset;
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char **vp;
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fill_tcpflag(u_char *set, u_char *reset, char **vp)
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{
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char *p = *vp,*q;
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u_char *d;
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@ -1066,6 +1083,45 @@ fill_tcpflag(set, reset, vp)
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}
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}
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static void
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fill_tcpopts(u_char *set, u_char *reset, char **vp)
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{
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char *p = *vp,*q;
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u_char *d;
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while (p && *p) {
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struct tpcopts {
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char * name;
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u_char value;
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} opts[] = {
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{ "mss", IP_FW_TCPOPT_MSS },
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{ "window", IP_FW_TCPOPT_WINDOW },
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{ "sack", IP_FW_TCPOPT_SACK },
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{ "ts", IP_FW_TCPOPT_TS },
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{ "cc", IP_FW_TCPOPT_CC },
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};
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int i;
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if (*p == '!') {
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p++;
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d = reset;
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} else {
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d = set;
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}
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q = strchr(p, ',');
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if (q)
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*q++ = '\0';
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for (i = 0; i < sizeof(opts) / sizeof(opts[0]); ++i)
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if (!strncmp(p, opts[i].name, strlen(p))) {
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*d |= opts[i].value;
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break;
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}
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if (i == sizeof(opts) / sizeof(opts[0]))
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show_usage("invalid tcp option ``%s''", p);
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p = q;
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}
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}
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static void
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fill_ipopt(u_char *set, u_char *reset, char **vp)
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{
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@ -1839,7 +1895,7 @@ add(ac,av)
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rule.fw_tcpnf |= IP_FW_TCPF_ACK;
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av++; ac--; continue;
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}
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if (!strncmp(*av,"tcpflags",strlen(*av))) {
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if (!strncmp(*av,"tcpflags",strlen(*av)) || !strncmp(*av,"tcpflgs",strlen(*av))) {
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av++; ac--;
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if (!ac)
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show_usage("missing argument"
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@ -1847,6 +1903,14 @@ add(ac,av)
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fill_tcpflag(&rule.fw_tcpf, &rule.fw_tcpnf, av);
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av++; ac--; continue;
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}
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if (!strncmp(*av,"tcpoptions",strlen(*av)) || !strncmp(*av, "tcpopts",strlen(*av))) {
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av++; ac--;
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if (!ac)
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show_usage("missing argument"
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" for ``tcpflags''");
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fill_tcpopts(&rule.fw_tcpopt, &rule.fw_tcpnopt, av);
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av++; ac--; continue;
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}
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}
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if (rule.fw_prot == IPPROTO_ICMP) {
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if (!strncmp(*av,"icmptypes",strlen(*av))) {
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@ -353,6 +353,73 @@ ipopts_match(struct ip *ip, struct ip_fw *f)
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return 0;
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}
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static int
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tcpopts_match(struct tcphdr *tcp, struct ip_fw *f)
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{
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register u_char *cp;
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int opt, optlen, cnt;
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u_char opts, nopts, nopts_sve;
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cp = (u_char *)(tcp + 1);
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cnt = (tcp->th_off << 2) - sizeof (struct tcphdr);
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opts = f->fw_tcpopt;
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nopts = nopts_sve = f->fw_tcpnopt;
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for (; cnt > 0; cnt -= optlen, cp += optlen) {
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opt = cp[0];
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if (opt == TCPOPT_EOL)
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break;
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if (opt == TCPOPT_NOP)
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optlen = 1;
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else {
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optlen = cp[1];
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if (optlen <= 0)
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break;
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}
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switch (opt) {
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default:
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break;
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case TCPOPT_MAXSEG:
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opts &= ~IP_FW_TCPOPT_MSS;
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nopts &= ~IP_FW_TCPOPT_MSS;
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break;
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case TCPOPT_WINDOW:
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opts &= ~IP_FW_TCPOPT_WINDOW;
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nopts &= ~IP_FW_TCPOPT_WINDOW;
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break;
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case TCPOPT_SACK_PERMITTED:
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case TCPOPT_SACK:
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opts &= ~IP_FW_TCPOPT_SACK;
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nopts &= ~IP_FW_TCPOPT_SACK;
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break;
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case TCPOPT_TIMESTAMP:
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opts &= ~IP_FW_TCPOPT_TS;
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nopts &= ~IP_FW_TCPOPT_TS;
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break;
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case TCPOPT_CC:
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case TCPOPT_CCNEW:
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case TCPOPT_CCECHO:
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opts &= ~IP_FW_TCPOPT_CC;
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nopts &= ~IP_FW_TCPOPT_CC;
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break;
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}
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if (opts == nopts)
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break;
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}
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if (opts == 0 && nopts == nopts_sve)
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return 1;
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else
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return 0;
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}
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static __inline int
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iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname)
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{
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@ -1143,6 +1210,9 @@ ip_fw_chk(struct ip **pip, int hlen,
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break;
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}
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tcp = (struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl);
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if (f->fw_tcpopt != f->fw_tcpnopt && !tcpopts_match(tcp, f))
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continue;
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if (f->fw_tcpf != f->fw_tcpnf && !tcpflg_match(tcp, f))
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continue;
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goto check_ports;
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@ -64,6 +64,7 @@ struct ip_fw {
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unsigned fw_icmptypes[IP_FW_ICMPTYPES_DIM]; /* ICMP types bitmap */
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} fw_uar;
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u_char fw_ipopt,fw_ipnopt; /* IP options set/unset */
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u_char fw_tcpopt,fw_tcpnopt; /* TCP options set/unset */
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u_char fw_tcpf,fw_tcpnf; /* TCP flags set/unset */
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long timestamp; /* timestamp (tv_sec) of last match */
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union ip_fw_if fw_in_if, fw_out_if; /* Incoming and outgoing interfaces */
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@ -229,6 +230,15 @@ struct ipfw_dyn_rule {
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#define IP_FW_IPOPT_RR 0x04
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#define IP_FW_IPOPT_TS 0x08
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/*
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* Definitions for TCP option names.
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*/
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#define IP_FW_TCPOPT_MSS 0x01
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#define IP_FW_TCPOPT_WINDOW 0x02
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#define IP_FW_TCPOPT_SACK 0x04
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#define IP_FW_TCPOPT_TS 0x08
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#define IP_FW_TCPOPT_CC 0x10
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/*
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* Definitions for TCP flags.
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*/
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