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https://github.com/the-tcpdump-group/tcpdump.git
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RIP: Modernize packet parsing style.
Enable ND_LONGJMP_FROM_TCHECK. Report invalid packets as invalid. Remove two redundant ND_TCHECK_SIZE() instances and an improvised snapshot end guard. Check bounds for the remaining part of the packet header after printing version and command, not before. Lose one pointer and one length variable in rip_print(), also account for the header size when estimating the number of routes. Update two tests.
This commit is contained in:
Denis Ovsienko
parent
4352d30878
commit
db3c742cd7
2
CHANGES
2
CHANGES
@ -2,7 +2,7 @@ Monthday, Month DD, YYYY by gharris and denis
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Summary for 5.0.0 tcpdump release (so far!)
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Source code:
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Use %zu when printing a sizeof to squelch compiler warnings
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AppleTalk, BOOTP, EGP, EIGRP, Geneve, L2TP, OLSR, PGM, RSVP, UDP: Modernize packet parsing style
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AppleTalk, BOOTP, EGP, EIGRP, Geneve, L2TP, OLSR, PGM, RIP, RSVP, UDP: Modernize packet parsing style
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EGP: Replace custom code with tok2str()
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EIGRP: Get the packet header fields right.
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UDP: Clean up address and port printing.
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67
print-rip.c
67
print-rip.c
@ -29,6 +29,7 @@
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#include "netdissect-stdinc.h"
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#define ND_LONGJMP_FROM_TCHECK
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#include "netdissect.h"
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#include "addrtoname.h"
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#include "extract.h"
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@ -195,7 +196,7 @@ rip_entry_print_v1(netdissect_options *ndo, const u_char *p,
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/* RFC 1058 */
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if (remaining < RIP_ROUTELEN)
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return (0);
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goto invalid;
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ND_TCHECK_SIZE(ni);
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family = GET_BE_U_2(ni->rip_family);
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if (family != BSD_AFNUM_INET && family != 0) {
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@ -220,7 +221,7 @@ rip_entry_print_v1(netdissect_options *ndo, const u_char *p,
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GET_IPADDR_STRING(ni->rip_dest),
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GET_BE_U_4(ni->rip_metric));
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return (RIP_ROUTELEN);
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trunc:
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invalid:
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return 0;
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}
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@ -233,7 +234,7 @@ rip_entry_print_v2(netdissect_options *ndo, const u_char *p,
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const struct rip_netinfo_v2 *ni;
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if (remaining < sizeof(*eh))
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return (0);
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goto invalid;
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ND_TCHECK_SIZE(eh);
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family = GET_BE_U_2(eh->rip_family);
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if (family == 0xFFFF) { /* variable-sized authentication structures */
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@ -248,9 +249,8 @@ rip_entry_print_v2(netdissect_options *ndo, const u_char *p,
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const struct rip_auth_crypto_v2 *ch;
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ch = (const struct rip_auth_crypto_v2 *)p;
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ND_TCHECK_SIZE(ch);
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if (remaining < sizeof(*ch))
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return (0);
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goto invalid;
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ND_PRINT("\n\t Auth header:");
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ND_PRINT(" Packet Len %u,",
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GET_BE_U_2(ch->rip_packet_len));
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@ -275,9 +275,8 @@ rip_entry_print_v2(netdissect_options *ndo, const u_char *p,
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print_unknown_data(ndo, p + sizeof(*eh), "\n\t ", RIP_ROUTELEN - sizeof(*eh));
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} else { /* BSD_AFNUM_INET or AFI 0 */
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ni = (const struct rip_netinfo_v2 *)p;
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ND_TCHECK_SIZE(ni);
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if (remaining < sizeof(*ni))
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return (0);
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goto invalid;
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ND_PRINT("\n\t AFI %s, %15s/%-2d, tag 0x%04x, metric: %u, next-hop: ",
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tok2str(bsd_af_values, "%u", family),
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GET_IPADDR_STRING(ni->rip_dest),
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@ -290,37 +289,26 @@ rip_entry_print_v2(netdissect_options *ndo, const u_char *p,
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ND_PRINT("self");
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}
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return (RIP_ROUTELEN);
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trunc:
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invalid:
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return 0;
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}
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void
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rip_print(netdissect_options *ndo,
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const u_char *dat, u_int length)
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const u_char *p, u_int len)
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{
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const struct rip *rp;
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uint8_t vers, cmd;
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const u_char *p;
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u_int len, routecount;
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unsigned entry_size;
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ndo->ndo_protocol = "rip";
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if (ndo->ndo_snapend < dat) {
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nd_print_trunc(ndo);
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return;
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}
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len = ND_BYTES_AVAILABLE_AFTER(dat);
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if (len > length)
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len = length;
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if (len < sizeof(*rp)) {
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nd_print_trunc(ndo);
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return;
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ND_PRINT(" (packet length %u)", len);
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goto invalid;
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}
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len -= sizeof(*rp);
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rp = (const struct rip *)dat;
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rp = (const struct rip *)p;
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ND_TCHECK_SIZE(rp);
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vers = GET_U_1(rp->rip_vers);
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ND_PRINT("%sRIPv%u",
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(ndo->ndo_vflag >= 1) ? "\n\t" : "",
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@ -330,10 +318,13 @@ rip_print(netdissect_options *ndo,
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cmd = GET_U_1(rp->rip_cmd);
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ND_PRINT(", %s, length: %u",
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tok2str(rip_cmd_values, "unknown command (%u)", cmd),
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length);
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len);
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ND_TCHECK_SIZE(rp);
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if (ndo->ndo_vflag < 1)
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return;
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p += sizeof(*rp);
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len -= sizeof(*rp);
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switch (cmd) {
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@ -342,21 +333,17 @@ rip_print(netdissect_options *ndo,
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switch (vers) {
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case 1:
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routecount = length / RIP_ROUTELEN;
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ND_PRINT(", routes: %u", routecount);
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p = (const u_char *)(rp + 1);
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ND_PRINT(", routes: %u", len / RIP_ROUTELEN);
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while (len != 0) {
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entry_size = rip_entry_print_v1(ndo, p, len);
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if (entry_size == 0) {
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/* Error */
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nd_print_trunc(ndo);
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break;
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goto invalid;
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}
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if (len < entry_size) {
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ND_PRINT(" [remaining entries length %u < %u]",
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len, entry_size);
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nd_print_invalid(ndo);
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break;
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goto invalid;
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}
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p += entry_size;
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len -= entry_size;
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@ -364,21 +351,17 @@ rip_print(netdissect_options *ndo,
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break;
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case 2:
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routecount = length / RIP_ROUTELEN;
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ND_PRINT(", routes: %u or less", routecount);
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p = (const u_char *)(rp + 1);
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ND_PRINT(", routes: %u or less", len / RIP_ROUTELEN);
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while (len != 0) {
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entry_size = rip_entry_print_v2(ndo, p, len);
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if (entry_size == 0) {
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/* Error */
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nd_print_trunc(ndo);
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break;
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goto invalid;
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}
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if (len < entry_size) {
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ND_PRINT(" [remaining entries length %u < %u]",
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len, entry_size);
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nd_print_invalid(ndo);
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break;
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goto invalid;
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}
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p += entry_size;
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len -= entry_size;
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@ -403,16 +386,18 @@ rip_print(netdissect_options *ndo,
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default:
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if (ndo->ndo_vflag <= 1) {
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if (!print_unknown_data(ndo, (const uint8_t *)rp, "\n\t", length))
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if (!print_unknown_data(ndo, p, "\n\t", len))
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return;
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}
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break;
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}
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/* do we want to see an additionally hexdump ? */
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if (ndo->ndo_vflag> 1) {
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if (!print_unknown_data(ndo, (const uint8_t *)rp, "\n\t", length))
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if (!print_unknown_data(ndo, p, "\n\t", len))
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return;
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}
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trunc:
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return;
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invalid:
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nd_print_invalid(ndo);
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ND_TCHECK_LEN(p, len);
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}
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@ -1,6 +1,6 @@
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1 08:36:15.227124 IP (tos 0xc0, ttl 2, id 0, offset 0, flags [none], proto UDP (17), length 192)
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10.7.56.254.520 > 224.0.0.9.520:
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RIPv2, Response, length: 160, routes: 8 or less
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RIPv2, Response, length: 160, routes: 7 or less
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AFI IPv4, 10.7.0.0/24, tag 0x0000, metric: 1, next-hop: self
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AFI IPv4, 10.7.41.0/24, tag 0x0000, metric: 1, next-hop: self
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AFI IPv4, 10.7.51.0/24, tag 0x0000, metric: 1, next-hop: self
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@ -40,7 +40,7 @@
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0x0010: 3375 fc89
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7 15:49:00.891527 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto UDP (17), length 108)
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10.0.0.20.520 > 224.0.0.9.520:
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RIPv2, Request, length: 80, routes: 4 or less
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RIPv2, Request, length: 80, routes: 3 or less
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Auth header: Packet Len 44, Key-ID 45, Auth Data Len 32, SeqNo 1339429740, MBZ 0, MBZ 0
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AFI 0, 0.0.0.0/0 , tag 0x0000, metric: 16, next-hop: self
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Auth trailer:
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@ -48,7 +48,7 @@
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0x0010: 451a bd20 cee4 8a3d a466 17a0 e550 5b4b
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8 15:49:04.890122 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto UDP (17), length 108)
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10.0.0.20.520 > 224.0.0.9.520:
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RIPv2, Response, length: 80, routes: 4 or less
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RIPv2, Response, length: 80, routes: 3 or less
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Auth header: Packet Len 44, Key-ID 45, Auth Data Len 32, SeqNo 1339429744, MBZ 0, MBZ 0
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AFI IPv4, 10.70.178.0/24, tag 0x0000, metric: 1, next-hop: self
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Auth trailer:
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