On 2019/09/11 14:34, Martijn van Duren wrote: > Found by a colleague and verified against latest tcpdump version. > > I don't know where the -1 comes from, but it is wrong. > > OK? > > martijn@ > > Index: print-cdp.c > =================================================================== > RCS file: /cvs/src/usr.sbin/tcpdump/print-cdp.c,v > retrieving revision 1.7 > diff -u -p -r1.7 print-cdp.c > --- print-cdp.c 5 Apr 2019 00:57:59 -0000 1.7 > +++ print-cdp.c 11 Sep 2019 12:33:51 -0000 > @@ -115,7 +115,7 @@ cdp_print(const u_char *p, u_int length, > case 0x0a: /* guess - not documented */ > if (len < 6) > goto error; > - printf(" Native-VLAN-ID %d", (p[i+4]<<8) + p[i+4+1] - 1 > ); > + printf(" Native-VLAN-ID %d", (p[i+4]<<8) + p[i+4+1]); > break; > case 0x0b: /* guess - not documented */ > if (len < 5) >
OK. There are some cisco docs that don't say anything about subtracting 1 (maybe replace the "guess - not documented" with the url while there? http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4500-series-switches/13414-103.html#cdp)