network_cmds-115.2.tar.gz

diff --git a/alias/alias.c b/alias/alias.c
index fffcae238162f6d7fa9d05d3812a36f8fa0bc74c..561245a16caadc1490dc032a4bb06c2895e404ad 100644 (file)
--- a/alias/alias.c
+++ b/alias/alias.c
@@ -164,6 +164,9 @@
     TcpMonitorIn()  -- These routines monitor TCP connections, and
     TcpMonitorOut()    delete a link when a connection is closed.
 
+       DoMSSClamp()    -- Clamps the MSS of the given TCP header to the
+                       value in packetAliasMSS.
+
 These routines look for SYN, FIN and RST flags to determine when TCP
 connections open and close.  When a TCP connection closes, the data
 structure containing packet aliasing information is deleted after
@@ -176,6 +179,55 @@ static void TcpMonitorIn(struct ip *, struct alias_link *);
 static void TcpMonitorOut(struct ip *, struct alias_link *);
 
 
+static u_short packetAliasMSS;
+
+void PacketAliasClampMSS(u_short mss)
+{
+    packetAliasMSS = mss;
+}
+
+static void DoMSSClamp(struct tcphdr *tc)
+{
+    u_char *option    = (u_char *) tc + sizeof(*tc);
+    u_char *optionEnd = option + ((tc->th_off << 2) - sizeof(*tc));
+
+    while (optionEnd > option)
+    {
+        switch (option[0])
+        {
+            case TCPOPT_EOL:
+                option = optionEnd;
+                break;
+
+            case TCPOPT_NOP:
+                ++option;
+                break;
+
+            case TCPOPT_MAXSEG:
+                if (option[1] == 4)
+                {
+                    u_short *mssPtr = (u_short *) option + 1;
+                    u_short mssVal  = ntohs(*mssPtr);
+
+                    if (packetAliasMSS < mssVal)
+                    {
+                        int accumulate = mssVal;
+                        accumulate -= packetAliasMSS;
+                        *mssPtr = htons(packetAliasMSS);
+                        ADJUST_CHECKSUM(accumulate, tc->th_sum);
+                    }
+
+                    option = optionEnd;
+                }
+                break;
+
+            default:
+                option += option[1];
+                break;
+        }
+    }
+}
+
 static void
 TcpMonitorIn(struct ip *pip, struct alias_link *link)
 {
@@ -189,7 +241,12 @@ TcpMonitorIn(struct ip *pip, struct alias_link *link)
             if (tc->th_flags & TH_RST)
                 SetStateIn(link, ALIAS_TCP_STATE_DISCONNECTED);
             else if (tc->th_flags & TH_SYN)
+            {
                 SetStateIn(link, ALIAS_TCP_STATE_CONNECTED);
+
+                if (packetAliasMSS)
+                    DoMSSClamp(tc);
+            }
             break;
         case ALIAS_TCP_STATE_CONNECTED:
             if (tc->th_flags & (TH_FIN | TH_RST))
@@ -211,7 +268,12 @@ TcpMonitorOut(struct ip *pip, struct alias_link *link)
             if (tc->th_flags & TH_RST)
                 SetStateOut(link, ALIAS_TCP_STATE_DISCONNECTED);
             else if (tc->th_flags & TH_SYN)
+            {
                 SetStateOut(link, ALIAS_TCP_STATE_CONNECTED);
+
+                if (packetAliasMSS)
+                    DoMSSClamp(tc);
+            }
             break;
         case ALIAS_TCP_STATE_CONNECTED:
             if (tc->th_flags & (TH_FIN | TH_RST))

diff --git a/alias/alias.h b/alias/alias.h
index 02d332d31bc57ac5b55f532d569505eaadff9e7d..a84dd6cbb7dea4b979040abfcd9ce76f241e3bd9 100644 (file)
--- a/alias/alias.h
+++ b/alias/alias.h
@@ -82,6 +82,9 @@ struct alias_link;
     PacketAliasSetFWBase(unsigned int, unsigned int);
 #endif
 
+    extern void
+    PacketAliasClampMSS(u_short mss);
+
 /* Packet Handling */
     extern int
     PacketAliasIn(char *, int maxpacketsize);

diff --git a/natd.tproj/natd.8 b/natd.tproj/natd.8
index c6f8e8e490a6a7eedaee5196dfb6a39217a0dbf6..e3786fa5b8f149470005f4699f594c3f7253a217 100644 (file)
--- a/natd.tproj/natd.8
+++ b/natd.tproj/natd.8
@@ -1,5 +1,5 @@
 .\" manual page [] for natd 1.4
-.\"    $Id: natd.8,v 1.4 2002/05/10 00:51:01 mscopp Exp $
+.\"    $Id: natd.8,v 1.4.32.1 2003/03/11 00:59:15 mscopp Exp $
 .Dd June 27, 2000
 .Os Darwin
 .Dt NATD 8
@@ -32,6 +32,7 @@
 .Op Fl log_denied
 .Op Fl log_facility Ar facility_name
 .Op Fl punch_fw Ar firewall_range
+.Op Fl clamp_mss
 .Ek
 .Sh DESCRIPTION
 This program provides a Network Address Translation facility for use
@@ -460,6 +461,12 @@ rules starting from the rule number
 .Ar basenumber
 will be used for punching firewall holes.
 The range will be cleared for all rules on startup.
+.It Fl clamp_mss Xo
+.Xc
+This option enables MSS clamping.  The MSS value is derived from the
+MTU of the interface specified in the
+.Fl interface
+option.
 .El
 .Sh RUNNING NATD
 The following steps are necessary before attempting to run

diff --git a/natd.tproj/natd.c b/natd.tproj/natd.c
index bea14a929c78b9603c3c1fce5c6422bfc299b63a..d6437672d216b5a7dc947bda7abc878a01469bd1 100644 (file)
--- a/natd.tproj/natd.c
+++ b/natd.tproj/natd.c
@@ -136,6 +136,7 @@ static      u_short                 outPort;
 static u_short                 inOutPort;
 static struct in_addr          aliasAddr;
 static         int                     dynamicMode;
+static  int                    clampMSS;
 static  int                    ifMTU;
 static int                     aliasOverhead;
 static         int                     icmpSock;
@@ -199,9 +200,6 @@ int main (int argc, char** argv)
        if (aliasAddr.s_addr == INADDR_NONE && ifName == NULL)
                errx (1, "aliasing address not given");
 
-       if (aliasAddr.s_addr != INADDR_NONE && ifName != NULL)
-               errx (1, "both alias address and interface "
-                        "name are not allowed");
 /*
  * Check that valid port number is known.
  */
@@ -784,6 +782,8 @@ SetAliasAddressFromIfName(const char *ifn)
                            strncmp(ifn, sdl->sdl_data, sdl->sdl_nlen) == 0) {
                                ifIndex = ifm->ifm_index;
                                ifMTU = ifm->ifm_data.ifi_mtu;
+                               if (clampMSS)
+                                       PacketAliasClampMSS(ifMTU - sizeof(struct tcphdr) - sizeof(struct ip));
                                break;
                        }
                }
@@ -793,6 +793,7 @@ SetAliasAddressFromIfName(const char *ifn)
 /*
  * Get interface address.
  */
+       if (aliasAddr.s_addr == INADDR_NONE) {
        sin = NULL;
        while (next < lim) {
                ifam = (struct ifa_msghdr *)next;
@@ -828,6 +829,7 @@ SetAliasAddressFromIfName(const char *ifn)
        PacketAliasSetAddress(sin->sin_addr);
        syslog(LOG_INFO, "Aliasing to %s, mtu %d bytes",
               inet_ntoa(sin->sin_addr), ifMTU);
+       }
 
        free(buf);
 }
@@ -888,6 +890,7 @@ enum Option {
        RedirectAddress,
        ConfigFile,
        DynamicMode,
+       ClampMSS,
        ProxyRule,
        LogDenied,
        LogFacility,
@@ -997,6 +1000,14 @@ static struct OptionInfo optionTable[] = {
                "dynamic",
                NULL },
        
+       { ClampMSS,
+               0,
+               YesNo,
+               "[yes|no]",
+               "enable TCP MSS clamping",
+               "clamp_mss",
+               NULL },
+       
        { InPort,
                0,
                Service,
@@ -1219,6 +1230,10 @@ static void ParseOption (const char* option, const char* parms)
                dynamicMode = yesNoValue;
                break;
 
+       case ClampMSS:
+               clampMSS = yesNoValue;
+               break;
+
        case InPort:
                inPort = uNumValue;
                break;

diff --git a/rlogin.tproj/krcmd.c b/rlogin.tproj/krcmd.c
index 51c5a66e61ca6eb200d31c9cce302081e1f8c73d..8f7710eeda95b3b198cc9bc86079af6652300c73 100644 (file)
--- a/rlogin.tproj/krcmd.c
+++ b/rlogin.tproj/krcmd.c
@@ -56,7 +56,7 @@
 
 
 /*
- *     $Source: /cvs/Darwin/src/live/network_cmds/rlogin.tproj/krcmd.c,v $
+ *     $Source: /cvs/root/network_cmds/rlogin.tproj/krcmd.c,v $
  *     $Header: /mit/kerberos/ucb/mit/kcmd/RCS/krcmd.c,v 5.1
  *             89/07/25 15:38:44 kfall Exp Locker: kfall $
  * static char *rcsid_kcmd_c =

diff --git a/rsh.tproj/rsh.c b/rsh.tproj/rsh.c
index 8e290a297a7114414624822f1d7b93c11b063fdd..2e60f42c626dca752fcc03e93705890d4ba634fc 100644 (file)
--- a/rsh.tproj/rsh.c
+++ b/rsh.tproj/rsh.c
@@ -56,8 +56,8 @@
 
 
 /*
- * $Source: /cvs/Darwin/src/live/network_cmds/rsh.tproj/rsh.c,v $
- * $Header: /cvs/Darwin/src/live/network_cmds/rsh.tproj/rsh.c,v 1.1.1.1 1999/05/02 03:58:17 wsanchez Exp $
+ * $Source: /cvs/root/network_cmds/rsh.tproj/rsh.c,v $
+ * $Header: /cvs/root/network_cmds/rsh.tproj/rsh.c,v 1.1.1.1 1999/05/02 03:58:17 wsanchez Exp $
  */
 
 #include <sys/types.h>