@@ -40,10 +40,6 @@ MODULE_AUTHOR(" Mohd Nawawi Mohamad Jamili <nawawi@tracenetworkcorporation.com>"
MODULE_DESCRIPTION("Xtables: PSD - portscan detection");
MODULE_ALIAS("ipt_psd");
-#define HF_DADDR_CHANGING 0x01
-#define HF_SPORT_CHANGING 0x02
-#define HF_TOS_CHANGING 0x04
-#define HF_TTL_CHANGING 0x08
/*
* Information we keep per each target port
@@ -51,8 +47,6 @@ MODULE_ALIAS("ipt_psd");
struct port {
u_int16_t number; /* port number */
u_int8_t proto; /* protocol number */
- u_int8_t and_flags; /* tcp ANDed flags */
- u_int8_t or_flags; /* tcp ORed flags */
};
/*
@@ -67,9 +61,6 @@ struct host {
int count; /* Number of ports in the list */
int weight; /* Total weight of ports in the list */
struct port ports[SCAN_MAX_COUNT - 1]; /* List of ports */
- unsigned char tos; /* TOS */
- unsigned char ttl; /* TTL */
- unsigned char flags; /* HF_ flags bitmask */
};
/*
@@ -111,26 +102,20 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
} _buf;
struct in_addr addr;
u_int16_t src_port,dest_port;
- u_int8_t tcp_flags, proto;
+ u_int8_t proto;
unsigned long now;
struct host *curr, *last, **head;
int hash, index, count;
/* Parameters from userspace */
const struct xt_psd_info *psdinfo = match->matchinfo;
- /* IP header */
iph = ip_hdr(pskb);
-
- /* Sanity check */
if (iph->frag_off & htons(IP_OFFSET)) {
pr_debug("sanity check failed\n");
return false;
}
- /* TCP or UDP ? */
proto = iph->protocol;
- /* Get the source address, source & destination ports, and TCP flags */
-
addr.s_addr = iph->saddr;
/* We're using IP address 0.0.0.0 for a special purpose here, so don't let
* them spoof us. [DHCP needs this feature - HW] */
@@ -148,7 +133,6 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
/* Yep, it's dirty */
src_port = tcph->source;
dest_port = tcph->dest;
- tcp_flags = *((u_int8_t*)tcph + 13);
} else if (proto == IPPROTO_UDP || proto == IPPROTO_UDPLITE) {
udph = skb_header_pointer(pskb, match->thoff,
sizeof(_buf.udph), &_buf.udph);
@@ -156,14 +140,11 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
return false;
src_port = udph->source;
dest_port = udph->dest;
- tcp_flags = 0;
} else {
pr_debug("protocol not supported\n");
return false;
}
- /* Use jiffies here not to depend on someone setting the time while we're
- * running; we need to be careful with possible return value overflows. */
now = jiffies;
spin_lock(&state.lock);
@@ -181,7 +162,6 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
} while ((curr = curr->next) != NULL);
if (curr != NULL) {
-
/* We know this address, and the entry isn't too old. Update it. */
if (now - curr->timestamp <= (psdinfo->delay_threshold*HZ)/100 &&
time_after_eq(now, curr->timestamp)) {
@@ -190,8 +170,6 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
for (index = 0; index < curr->count; index++) {
if (curr->ports[index].number == dest_port) {
curr->ports[index].proto = proto;
- curr->ports[index].and_flags &= tcp_flags;
- curr->ports[index].or_flags |= tcp_flags;
goto out_no_match;
}
}
@@ -203,26 +181,15 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
/* Packet to a new port, and not TCP/ACK: update the timestamp */
curr->timestamp = now;
- /* Logged this scan already? Then drop the packet. */
+ /* Matched this scan already? Then Leave. */
if (curr->weight >= psdinfo->weight_threshold)
goto out_match;
- /* Specify if destination address, source port, TOS or TTL are not fixed */
- if (curr->dest_addr.s_addr != iph->daddr)
- curr->flags |= HF_DADDR_CHANGING;
- if (curr->src_port != src_port)
- curr->flags |= HF_SPORT_CHANGING;
- if (curr->tos != iph->tos)
- curr->flags |= HF_TOS_CHANGING;
- if (curr->ttl != iph->ttl)
- curr->flags |= HF_TTL_CHANGING;
-
/* Update the total weight */
curr->weight += (ntohs(dest_port) < 1024) ?
psdinfo->lo_ports_weight : psdinfo->hi_ports_weight;
/* Got enough destination ports to decide that this is a scan? */
- /* Then log it and drop the packet. */
if (curr->weight >= psdinfo->weight_threshold)
goto out_match;
@@ -230,8 +197,6 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
if (curr->count < ARRAY_SIZE(curr->ports)) {
curr->ports[curr->count].number = dest_port;
curr->ports[curr->count].proto = proto;
- curr->ports[curr->count].and_flags = tcp_flags;
- curr->ports[curr->count].or_flags = tcp_flags;
curr->count++;
}
@@ -303,10 +268,6 @@ xt_psd_match(const struct sk_buff *pskb, struct xt_action_param *match)
curr->weight = (ntohs(dest_port) < 1024) ? psdinfo->lo_ports_weight : psdinfo->hi_ports_weight;
curr->ports[0].number = dest_port;
curr->ports[0].proto = proto;
- curr->ports[0].and_flags = tcp_flags;
- curr->ports[0].or_flags = tcp_flags;
- curr->tos = iph->tos;
- curr->ttl = iph->ttl;
out_no_match:
spin_unlock(&state.lock);