Program received signal SIGSEGV, Segmentation fault.
pkt_get_seqnum (pkt=pkt@entry=0x0) at src/pkt.c:185
185     return pkt->seqnum;
(gdb) backtrace
#0  pkt_get_seqnum (pkt=pkt@entry=0x0) at src/pkt.c:185
#1  0x0000000000403763 in read_write_loop (sfd=4, file=0x407260) at src/read_write_loop.c:119
#2  0x0000000000402311 in main (argc=<optimized out>, argv=0x7fffffffd838) at src/sender.c:90
(gdb)