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Any packet that can be matched by a ipfw rule can be redirected transparently to another port or machine. Redirection to another port mostly makes sense with tcp, where a session can be set up between a proxy and an unsuspecting client. Redirection to another machine requires that the other machine also be expecting to receive the forwarded packets, as their headers will not have been modified. /sbin/ipfw must be recompiled!!! Reviewed by: Peter Wemm <peter@freebsd.org> Submitted by: Chrisy Luke <chrisy@flix.net>
190 lines
6.3 KiB
C
190 lines
6.3 KiB
C
/*
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* Copyright (c) 1993 Daniel Boulet
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* Copyright (c) 1994 Ugen J.S.Antsilevich
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*
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* Redistribution and use in source forms, with and without modification,
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* are permitted provided that this entire comment appears intact.
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*
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* Redistribution in binary form may occur without any restrictions.
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* Obviously, it would be nice if you gave credit where credit is due
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* but requiring it would be too onerous.
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*
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* This software is provided ``AS IS'' without any warranties of any kind.
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*
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* $Id: ip_fw.h,v 1.32 1998/02/03 22:15:03 bde Exp $
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*/
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#ifndef _IP_FW_H
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#define _IP_FW_H
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#include <sys/queue.h>
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/*
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* This union structure identifies an interface, either explicitly
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* by name or implicitly by IP address. The flags IP_FW_F_IIFNAME
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* and IP_FW_F_OIFNAME say how to interpret this structure. An
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* interface unit number of -1 matches any unit number, while an
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* IP address of 0.0.0.0 indicates matches any interface.
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*
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* The receive and transmit interfaces are only compared against the
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* the packet if the corresponding bit (IP_FW_F_IIFACE or IP_FW_F_OIFACE)
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* is set. Note some packets lack a receive or transmit interface
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* (in which case the missing "interface" never matches).
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*/
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union ip_fw_if {
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struct in_addr fu_via_ip; /* Specified by IP address */
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struct { /* Specified by interface name */
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#define FW_IFNLEN IFNAMSIZ
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char name[FW_IFNLEN];
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short unit; /* -1 means match any unit */
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} fu_via_if;
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};
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/*
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* Format of an IP firewall descriptor
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*
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* fw_src, fw_dst, fw_smsk, fw_dmsk are always stored in network byte order.
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* fw_flg and fw_n*p are stored in host byte order (of course).
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* Port numbers are stored in HOST byte order.
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* Warning: setsockopt() will fail if sizeof(struct ip_fw) > MLEN (108)
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*/
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struct ip_fw {
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u_int64_t fw_pcnt,fw_bcnt; /* Packet and byte counters */
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struct in_addr fw_src, fw_dst; /* Source and destination IP addr */
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struct in_addr fw_smsk, fw_dmsk; /* Mask for src and dest IP addr */
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u_short fw_number; /* Rule number */
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u_short fw_flg; /* Flags word */
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#define IP_FW_MAX_PORTS 10 /* A reasonable maximum */
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union {
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u_short fw_pts[IP_FW_MAX_PORTS]; /* Array of port numbers to match */
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#define IP_FW_ICMPTYPES_MAX 128
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#define IP_FW_ICMPTYPES_DIM (IP_FW_ICMPTYPES_MAX / (sizeof(unsigned) * 8))
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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_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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union {
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u_short fu_divert_port; /* Divert/tee port (options IPDIVERT) */
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u_short fu_skipto_rule; /* SKIPTO command rule number */
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u_short fu_reject_code; /* REJECT response code */
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struct sockaddr_in fu_fwd_ip;
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} fw_un;
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u_char fw_prot; /* IP protocol */
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u_char fw_nports; /* N'of src ports and # of dst ports */
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/* in ports array (dst ports follow */
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/* src ports; max of 10 ports in all; */
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/* count of 0 means match all ports) */
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};
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#define IP_FW_GETNSRCP(rule) ((rule)->fw_nports & 0x0f)
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#define IP_FW_SETNSRCP(rule, n) do { \
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(rule)->fw_nports &= ~0x0f; \
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(rule)->fw_nports |= (n); \
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} while (0)
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#define IP_FW_GETNDSTP(rule) ((rule)->fw_nports >> 4)
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#define IP_FW_SETNDSTP(rule, n) do { \
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(rule)->fw_nports &= ~0xf0; \
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(rule)->fw_nports |= (n) << 4;\
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} while (0)
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#define fw_divert_port fw_un.fu_divert_port
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#define fw_skipto_rule fw_un.fu_skipto_rule
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#define fw_reject_code fw_un.fu_reject_code
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#define fw_fwd_ip fw_un.fu_fwd_ip
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struct ip_fw_chain {
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LIST_ENTRY(ip_fw_chain) chain;
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struct ip_fw *rule;
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};
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/*
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* Values for "flags" field .
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*/
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#define IP_FW_F_IN 0x0001 /* Check inbound packets */
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#define IP_FW_F_OUT 0x0002 /* Check outbound packets */
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#define IP_FW_F_IIFACE 0x0004 /* Apply inbound interface test */
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#define IP_FW_F_OIFACE 0x0008 /* Apply outbound interface test */
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#define IP_FW_F_COMMAND 0x0070 /* Mask for type of chain entry: */
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#define IP_FW_F_DENY 0x0000 /* This is a deny rule */
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#define IP_FW_F_REJECT 0x0010 /* Deny and send a response packet */
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#define IP_FW_F_ACCEPT 0x0020 /* This is an accept rule */
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#define IP_FW_F_COUNT 0x0030 /* This is a count rule */
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#define IP_FW_F_DIVERT 0x0040 /* This is a divert rule */
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#define IP_FW_F_TEE 0x0050 /* This is a tee rule */
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#define IP_FW_F_SKIPTO 0x0060 /* This is a skipto rule */
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#define IP_FW_F_FWD 0x0070 /* This is a "change forwarding address" rule */
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#define IP_FW_F_PRN 0x0080 /* Print if this rule matches */
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#define IP_FW_F_SRNG 0x0100 /* The first two src ports are a min *
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* and max range (stored in host byte *
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* order). */
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#define IP_FW_F_DRNG 0x0200 /* The first two dst ports are a min *
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* and max range (stored in host byte *
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* order). */
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#define IP_FW_F_IIFNAME 0x0400 /* In interface by name/unit (not IP) */
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#define IP_FW_F_OIFNAME 0x0800 /* Out interface by name/unit (not IP) */
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#define IP_FW_F_INVSRC 0x1000 /* Invert sense of src check */
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#define IP_FW_F_INVDST 0x2000 /* Invert sense of dst check */
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#define IP_FW_F_FRAG 0x4000 /* Fragment */
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#define IP_FW_F_ICMPBIT 0x8000 /* ICMP type bitmap is valid */
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#define IP_FW_F_MASK 0xFFFF /* All possible flag bits mask */
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/*
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* For backwards compatibility with rules specifying "via iface" but
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* not restricted to only "in" or "out" packets, we define this combination
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* of bits to represent this configuration.
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*/
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#define IF_FW_F_VIAHACK (IP_FW_F_IN|IP_FW_F_OUT|IP_FW_F_IIFACE|IP_FW_F_OIFACE)
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/*
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* Definitions for REJECT response codes.
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* Values less than 256 correspond to ICMP unreachable codes.
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*/
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#define IP_FW_REJECT_RST 0x0100 /* TCP packets: send RST */
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/*
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* Definitions for IP option names.
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*/
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#define IP_FW_IPOPT_LSRR 0x01
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#define IP_FW_IPOPT_SSRR 0x02
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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 flags.
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*/
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#define IP_FW_TCPF_FIN TH_FIN
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#define IP_FW_TCPF_SYN TH_SYN
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#define IP_FW_TCPF_RST TH_RST
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#define IP_FW_TCPF_PSH TH_PUSH
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#define IP_FW_TCPF_ACK TH_ACK
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#define IP_FW_TCPF_URG TH_URG
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#define IP_FW_TCPF_ESTAB 0x40
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/*
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* Main firewall chains definitions and global var's definitions.
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*/
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#ifdef KERNEL
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/*
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* Function definitions.
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*/
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void ip_fw_init __P((void));
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#endif /* KERNEL */
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#endif /* _IP_FW_H */
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