[PACKET_IO]fix pcap file mode counter bug

ci/travis.sh

@@ -52,6 +52,8 @@ cmake3 -DCMAKE_CXX_FLAGS=$CXX_FLAGS \
 make
 make test
 
+cp -r ../src/packet_io/test/test-64.pcapng ./src/packet_io_test/
+
 if [ -n "${PACKAGE}" ]; then
   make package
   cp ~/rpm_upload_tools.py ./
@@ -64,3 +66,12 @@ if [ -n "${UPLOAD_SYMBOL_FILES}" ]; then
   cp /usr/lib/debug/opt/tsg/stellar/bin/stellar*debug /tmp/stellar.debuginfo.${CI_COMMIT_SHORT_SHA}
   sentry-cli upload-dif -t elf /tmp/stellar.debuginfo.${CI_COMMIT_SHORT_SHA}
 fi
+
+# create tun device
+ip tuntap add dev tun0 mode tun
+
+# add ip addr for tun device
+ip addr add 192.168.3.11/24 dev tun0
+
+# kernel open ip forward
+echo 1 > /proc/sys/inet/ipv4/ip_forward