rocky10 and trixie-publish

Erspan Support

See merge request cramer/pcapmirror!1

.gitlab-ci.yml

@@ -1,11 +1,10 @@
-
 stages:
   - build
   - publish
   
 variables:
   DEBIAN_FRONTEND: noninteractive
-  VERSION: 0.5
+  VERSION: 0.6
 
 build-bookworm:
   stage: build
@@ -13,7 +12,8 @@ build-bookworm:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic 
+  image: debian-package-builder-bookworm:v1
   script:
     - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
     - apt-get update && apt-get install -y libpcap-dev
@@ -34,11 +34,45 @@ publish-bookworm:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
-    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-1_amd64.deb'
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-deb12_amd64.deb'
+
+build-trixie:
+  stage: build
+  needs: []
+  only:
+    - tags
+  tags:
+    - docker-generic 
+  image: debian-package-builder-trixie:v1
+  script:
+    - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
+    - apt-get update && apt-get install -y libpcap-dev
+    - dpkg-buildpackage -uc -us
+    - mkdir -p build
+    - mv ../pcapmirror*.* build/
+
+  artifacts:
+    paths:
+      - build
+
+publish-trixie:
+  stage: publish
+  needs:
+    - build-trixie
+  dependencies:
+    - build-trixie
+  only:
+    - tags
+  tags:
+    - docker-generic
+  image: debian-package-builder-trixie:v1
+  script:
+    - ls -la build
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/trixie/pcapmirror_$VERSION-deb13_amd64.deb'
 
 build-sid:
   stage: build
@@ -46,7 +80,8 @@ build-sid:
   only:
     - tags
   tags:
-    - sid
+    - docker-generic 
+  image: debian-package-builder-sid:v1
   script:
     - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
     - apt-get update && apt-get install -y libpcap-dev
@@ -67,11 +102,48 @@ publish-sid:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
-    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/sid/pcapmirror_$VERSION-1_amd64.deb'
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/sid/pcapmirror_$VERSION-sid_amd64.deb'
+
+build-rocky10:
+  stage: build
+  needs: []
+  only:
+    - tags
+  tags:
+    - docker-generic 
+  image: rockylinux-package-builder-10:v1
+  script:
+    - dnf install -y libpcap-devel
+    - mkdir -p /root/rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
+    - tar -czf /root/rpmbuild/SOURCES/pcapmirror-v${VERSION}.tar.gz --exclude=debian --exclude=.git .
+    - cp -r * /root/rpmbuild/BUILD
+    - rpmbuild -ba pcapmirror.spec
+    - mkdir -p build
+    - mv /root/rpmbuild/RPMS/x86_64/pcapmirror*.* build/
+    - mv /root/rpmbuild/SRPMS/pcapmirror*.* build/
+
+  artifacts:
+    paths:
+      - build
+
+publish-rocky10:
+  stage: publish
+  needs:
+    - build-rocky10
+  dependencies:
+    - build-rocky10
+  only:
+    - tags
+  tags:
+    - docker-generic
+  image: debian-package-builder-trixie:v1
+  script:
+    - ls -la build
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror-$VERSION-*.el10.x86_64.rpm ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/rockylinux10/pcapmirror-$VERSION-1.el10.x86_64.rpm'
 
 build-rocky9:
   stage: build
@@ -79,11 +151,12 @@ build-rocky9:
   only:
     - tags
   tags:
-    - rocky9
+    - docker-generic 
+  image: rockylinux-package-builder-9:v1
   script:
     - dnf install -y libpcap-devel
     - mkdir -p /root/rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
-    - tar -czf /root/rpmbuild/SOURCES/pcapmirror-v$VERSION.tar.gz --exclude=debian --exclude=.git .
+    - tar -czf /root/rpmbuild/SOURCES/pcapmirror-v${VERSION}.tar.gz --exclude=debian --exclude=.git .
     - cp -r * /root/rpmbuild/BUILD
     - rpmbuild -ba pcapmirror.spec
     - mkdir -p build
@@ -103,11 +176,11 @@ publish-rocky9:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
-    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror-$VERSION-*.el9.x86_64.rpm ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/rockylinux9/pcapmirror-$VERSION-1.el8.x86_64.rpm'
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror-$VERSION-*.el9.x86_64.rpm ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/rockylinux9/pcapmirror-$VERSION-1.el9.x86_64.rpm'
 
 build-rocky8:
   stage: build
@@ -115,11 +188,12 @@ build-rocky8:
   only:
     - tags
   tags:
-    - rocky8
+    - docker-generic 
+  image: rockylinux-package-builder-8:v1
   script:
     - dnf install -y libpcap-devel
     - mkdir -p /root/rpmbuild/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
-    - tar -czf /root/rpmbuild/SOURCES/pcapmirror-v$VERSION.tar.gz --exclude=debian --exclude=.git .
+    - tar -czf /root/rpmbuild/SOURCES/pcapmirror-v${VERSION}.tar.gz --exclude=debian --exclude=.git .
     - cp -r * /root/rpmbuild/BUILD
     - rpmbuild -ba pcapmirror.spec
     - mkdir -p build
@@ -139,9 +213,9 @@ publish-rocky8:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
     - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror-$VERSION-*.el8.x86_64.rpm ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/rockylinux8/pcapmirror-$VERSION-1.el8.x86_64.rpm'
 
@@ -151,7 +225,8 @@ build-pios12:
   only:
     - tags
   tags:
-    - pios12
+    - docker-generic
+  image: pios-package-builder-bookworm:v1
   script:
     - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
     - apt-get update && apt-get install -y libpcap-dev
@@ -172,11 +247,11 @@ publish-pios12:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
-    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_armhf.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-1_armhf.deb'
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_armhf.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-piso12_armhf.deb'
 
 build-pios12-64:
   stage: build
@@ -184,7 +259,8 @@ build-pios12-64:
   only:
     - tags
   tags:
-    - pios12-64
+    - docker-generic
+  image: pios-package-builder-bookworm:64-v1
   script:
     - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
     - apt-get update && apt-get install -y libpcap-dev
@@ -205,8 +281,77 @@ publish-pios12-64:
   only:
     - tags
   tags:
-    - bookworm
+    - docker-generic
+  image: debian-package-builder-trixie:v1
   script:
-    - apt-get update && apt-get install -y curl
     - ls -la build
-    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_arm64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-1_arm64.deb'
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_arm64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/bookworm/pcapmirror_$VERSION-pios12_arm64.deb'
+
+build-plucky:
+  stage: build
+  needs: []
+  only:
+    - tags
+  tags:
+    - docker-generic 
+  image: ubuntu-package-builder-plucky:v1
+  script:
+    - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
+    - apt-get update && apt-get install -y libpcap-dev
+    - dpkg-buildpackage -uc -us
+    - mkdir -p build
+    - mv ../pcapmirror*.* build/
+
+  artifacts:
+    paths:
+      - build
+
+publish-plucky:
+  stage: publish
+  needs:
+    - build-plucky
+  dependencies:
+    - build-plucky
+  only:
+    - tags
+  tags:
+    - docker-generic
+  image: debian-package-builder-trixie:v1
+  script:
+    - ls -la build
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/trixie/pcapmirror_$VERSION-ubu25.04_amd64.deb'
+
+build-noble:
+  stage: build
+  needs: []
+  only:
+    - tags
+  tags:
+    - docker-generic 
+  image: ubuntu-package-builder-noble:v1
+  script:
+    - tar -czf ../pcapmirror_$VERSION.orig.tar.gz --exclude=debian .
+    - apt-get update && apt-get install -y libpcap-dev
+    - dpkg-buildpackage -uc -us
+    - mkdir -p build
+    - mv ../pcapmirror*.* build/
+
+  artifacts:
+    paths:
+      - build
+
+publish-noble:
+  stage: publish
+  needs:
+    - build-noble
+  dependencies:
+    - build-noble
+  only:
+    - tags
+  tags:
+    - docker-generic
+  image: debian-package-builder-trixie:v1
+  script:
+    - ls -la build
+    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file build/pcapmirror_$VERSION-1_amd64.deb ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/pcapmirror/trixie/pcapmirror_$VERSION-ubu24.04_amd64.deb'
+

Makefile

@@ -24,6 +24,9 @@ PREFIX = /usr
 # Default rule
 all: $(TARGET) man
 
+static: $(OBJS)
+		$(CC) $(CFLAGS) -static $(OBJS) -o $(TARGET) $(LIBS) -ldbus-1 -lsystemd -lcap
+
 # Create executable
 $(TARGET): $(OBJS)
 		$(CC) $(CFLAGS) $(OBJS) -o $(TARGET) $(LIBS)
@@ -37,7 +40,7 @@ man:
 
 # Clean up object files and executable
 clean:
-		rm -f -f $(OBJS) $(TARGET)
+		rm -f -f $(OBJS) $(TARGET) pcapmirror.8.gz
 
 # Install the executable
 install: $(TARGET)

README.md

@@ -2,7 +2,7 @@
 # pcapmirror
 ![pcapmirror logo](logo/pcapmirror_logo_small.png)
 
-pcapmirror is a command-line tool for capturing network traffic and mirroring it to a remote destination using [TZSP encapsulation](https://en.wikipedia.org/wiki/TZSP). It leverages the `libpcap` library for packet capture and provides options for filtering traffic based on BPF syntax. This tool is useful for network monitoring, intrusion detection, and remote packet analysis.
+pcapmirror is a command-line tool for capturing network traffic and mirroring it to a remote destination using [TZSP encapsulation](https://en.wikipedia.org/wiki/TZSP) or [ERSPAN](https://datatracker.ietf.org/doc/html/draft-foschiano-erspan-01). It leverages the `libpcap` library for packet capture and provides options for filtering traffic based on BPF syntax. This tool is useful for network monitoring, intrusion detection, and remote packet analysis.
 
 ## Usage
 
@@ -16,6 +16,9 @@ pcapmirror [options]
 * -f <filter> Specify the capture filter (BPF syntax)
 * -r <host/ipv4/ipv6> Specify the destination host (required)
 * -p <port> Specify the destination port (default: 37008)
+* -e Use ERSPAN encapsulation (default: TZSP)
+* -s <source_ip> Specify the source IP address (required for ERSPAN)
+* -S <session_id> Specify the session ID (default: 42, must be between 0 and 1023)
 * -4 Force IPv4 host lookup
 * -6 Force IPv6 host lookup
 * -l List available network interfaces.

debian/changelog

@@ -1,3 +1,11 @@
+pcapmirror (0.6-1) unstable; urgency=medium
+
+  * Erspan Encapsulation support
+  * added option -e to set the encapsulation type
+  * added option -S to set ERSPAN session id
+
+ -- Matthias Cramer <cramer@freestone.net>  Sun, 20 Apr 2025 16:50:00 +0200
+
 pcapmirror (0.5-1) unstable; urgency=medium
 
   * new option -c to count matching packets (overrides verbose mode)

debian/control

@@ -11,7 +11,7 @@ Architecture: any
 Depends: ${shlibs:Depends}, ${misc:Depends}, libpcap0.8
 Description: A simple packet mirroring tool using libpcap
  pcapmirror is a command-line tool for capturing network traffic and
- mirroring it to a remote destination using TZSP encapsulation. It
+ mirroring it to a remote destination using TZSP or ERSPAN encapsulation.
- leverages the libpcap library for packet capture and provides options
+ It leverages the libpcap library for packet capture and provides options
  for filtering traffic based on BPF syntax. This tool is useful for
  network monitoring, intrusion detection, and remote packet analysis.

main.c

@@ -38,6 +38,19 @@ struct tzsp_tagged {
     unsigned char type;         // Tag type
 };
 
+// GRE Header Structure
+struct gre_header {
+    uint16_t flags;      // GRE flags
+    uint16_t protocol;   // Protocol type (0x88BE for ERSPAN)
+};
+
+// ERSPAN Header Structure
+// ERSPAN Type II Header Structure
+struct erspan_header {
+    uint32_t ver_vlan_cos_en_t_session; // Ver (4 bits), VLAN (12 bits), COS (3 bits), En (1 bit), T (1 bit), Session ID (10 bits)
+    uint32_t reserved_index;            // Reserved (12 bits), Index (20 bits)
+};
+
 // Add this structure for ARP header parsing
 struct arp_header {
     uint16_t htype;    // Hardware type
@@ -51,12 +64,6 @@ struct arp_header {
     uint8_t tpa[4];    // Target protocol address
 };
 
-// Function to check if the system is little-endian
-int is_little_endian() {
-    volatile unsigned int i=0x01234567;
-    return (((unsigned char*)&i)[0] == 0x67);
-}
-
 void list_interfaces() {
     pcap_if_t *alldevs;
     char errbuf[PCAP_ERRBUF_SIZE];
@@ -119,6 +126,9 @@ void print_usage(const char *program_name) {
     printf("  -f <filter>          Specify the capture filter (BPF syntax)\n");
     printf("  -r <host/ipv4/ipv6>  Specify the destination host (required)\n");
     printf("  -p <port>            Specify the destination port (default: %d)\n", DEFAULT_DEST_PORT);
+    printf("  -e                   Use ERSPAN encapsulation (default: TZSP)\n");
+    printf("  -s <source_ip>       Specify the source IP address (required for ERSPAN)\n");
+    printf("  -S <session_id>      Specify the session ID (default: 42, must be between 0 and 1023)\n");
     printf("  -4                   Force IPv4 host lookup\n");
     printf("  -6                   Force IPv6 host lookup\n");
     printf("  -l                   List available network interfaces\n");
@@ -145,6 +155,10 @@ int main(int argc, char *argv[]) {
     int count_packets = 0; // Flag for counting packets
     unsigned long long int packet_count = 0;  // Counter for matching packets (64bit)
 
+    int use_erspan = 0; // Flag for ERSPAN encapsulation
+    char *source_address = NULL; // Source IP address, default is NULL
+    uint32_t session_id = 42;      // Session ID (10 bits)
+
     // Socket variables
     int sockfd;
     struct addrinfo hints, *res;
@@ -185,6 +199,18 @@ int main(int argc, char *argv[]) {
         } else if (strcmp(argv[i], "-c") == 0) {
             count_packets = 1; // Enable packet counting
             verbose = 0;       // Disable verbose mode if -c is set
+        } else if (strcmp(argv[i], "-e") == 0) {
+            use_erspan = 1; // Enable ERSPAN encapsulation
+        } else if (strcmp(argv[i], "-s") == 0 && i + 1 < argc) {
+            source_address = argv[i + 1]; // Set source IP from command line
+            i++; // Skip the source IP value
+        } else if (strcmp(argv[i], "-S") == 0 && i + 1 < argc) {
+            session_id = atoi(argv[i + 1]); // Set session ID from command line
+            if (session_id > 1023) { // Validate session ID (must fit in 10 bits)
+                fprintf(stderr, "Error: Session ID must be between 0 and 1023.\n");
+                return 1;
+            }
+            i++; // Skip the session ID value
         }
     }
 
@@ -206,6 +232,12 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    // Check if the interface is specified
+    if (dev_name == NULL) {
+        fprintf(stderr, "Error: Interface must be specified\n");
+        return 1;
+    }
+
     // Resolve the destination address
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = AF_UNSPEC; // Allow IPv4 or IPv6
@@ -233,13 +265,32 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
-    // Create UDP socket
+    if (use_erspan) {
+        // Create a raw socket for ERSPAN
+        sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_GRE);
+        if (sockfd == -1) {
+            perror("socket");
+            freeaddrinfo(res);
+            return 1;
+        }
+    
+        // Set the IP_HDRINCL option to include the IP header in the packet
+        int optval = 1;
+        if (setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &optval, sizeof(optval)) == -1) {
+            perror("setsockopt");
+            close(sockfd);
+            freeaddrinfo(res);
+            return 1;
+        }
+    } else {
+        // Create a UDP socket for TZSP
         sockfd = socket(res->ai_family, SOCK_DGRAM, 0);
         if (sockfd == -1) {
             perror("socket");
             freeaddrinfo(res);
             return 1;
         }
+    }
 
     memset(&dest_addr, 0, sizeof(dest_addr));
 
@@ -308,6 +359,7 @@ int main(int argc, char *argv[]) {
     struct ip6_hdr *ip6_header; // Declare ip6_header
     int ip_protocol = 0;
     struct timeval current_time, last_count;
+    static uint32_t sequence_number = 0; // Sequence number for ERSPAN packets
 
     gettimeofday(&last_count, NULL);
     printf("\n");
@@ -394,6 +446,104 @@ int main(int argc, char *argv[]) {
             }
         }
 
+        // Encapsulation logic
+        if (use_erspan) {
+            // ERSPAN Encapsulation
+            struct ip ip_header;
+            struct gre_header gre;
+            struct erspan_header erspan;
+        
+            // Set IP header fields
+            memset(&ip_header, 0, sizeof(ip_header));
+            ip_header.ip_hl = 5; // Header length (5 * 4 = 20 bytes)
+            ip_header.ip_v = 4;  // IPv4
+            ip_header.ip_tos = 0; // Type of Service
+            ip_header.ip_len = htons(sizeof(ip_header) + sizeof(gre) + sizeof(sequence_number) + sizeof(erspan) + header.caplen);
+            ip_header.ip_id = htons(0); // Identification
+            ip_header.ip_off = 0; // Fragment offset
+            ip_header.ip_ttl = 64; // Time to live
+            ip_header.ip_p = IPPROTO_GRE; // Protocol (GRE)
+            ip_header.ip_dst.s_addr = ((struct sockaddr_in *)&dest_addr)->sin_addr.s_addr;
+            
+            if (source_address != NULL) {
+                if (inet_pton(AF_INET, source_address, &(ip_header.ip_src)) != 1) {
+                    fprintf(stderr, "Error: Invalid source IP address '%s'\n", source_address);
+                    return 1;
+                }
+            } else {
+                ip_header.ip_src.s_addr = inet_addr("192.168.1.1"); // Default source IP
+            }
+
+            ip_header.ip_src.s_addr = inet_addr("192.168.1.1"); // Replace with your source IP
+        
+            // Set GRE header fields
+            gre.flags = htons(0x1000); // GRE flags (S bit set for Sequence Number Present)
+            gre.protocol = htons(0x88BE); // ERSPAN protocol type
+        
+            // Set ERSPAN header fields
+            uint32_t version = 1;          // Version (4 bits)
+            uint32_t vlan = 100;           // VLAN ID (12 bits)
+            uint32_t cos = 5;              // Class of Service (3 bits)
+            uint32_t en = 0;               // Trunk Encapsulation Type (2 bit)
+            uint32_t t = 1;                // Truncated (1 bit)
+
+            // Combine fields into the 32-bit ver_vlan_cos_en_t_session field
+            erspan.ver_vlan_cos_en_t_session = 
+                ((version & 0xF) << 28) |  // Version (4 bits, shifted to bits 28-31)
+                ((vlan & 0xFFF) << 16) |   // VLAN ID (12 bits, shifted to bits 16-27)
+                ((cos & 0x7) << 13) |      // Class of Service (3 bits, shifted to bits 13-15)
+                ((en & 0x3) << 11) |       // Trunk Encapsulation Type (2 bit, bit 12)
+                ((t & 0x1) << 10) |        // Truncated (1 bit, bit 11)
+                (session_id & 0x3FF);      // Session ID (10 bits, bits 0-9)
+
+            // Convert to network byte order
+            erspan.ver_vlan_cos_en_t_session = htonl(erspan.ver_vlan_cos_en_t_session);
+
+            // Set the reserved and index fields
+            uint32_t reserved = 0;         // Reserved (12 bits)
+            uint32_t index = 12345;        // Index (20 bits)
+
+            // Combine fields into the 32-bit reserved_index field
+            erspan.reserved_index = 
+                ((reserved & 0xFFF) << 20) | // Reserved (12 bits, bits 20-31)
+                (index & 0xFFFFF);           // Index (20 bits, bits 0-19)
+
+            // Convert to network byte order
+            erspan.reserved_index = htonl(erspan.reserved_index);
+        
+            // Calculate total length
+            unsigned short total_length = sizeof(ip_header) + sizeof(gre) + sizeof(sequence_number) + sizeof(erspan) + header.caplen;
+        
+            // Allocate memory for ERSPAN packet
+            unsigned char *erspan_packet = (unsigned char *)malloc(total_length);
+            if (erspan_packet == NULL) {
+                perror("malloc");
+                continue; // Skip this packet
+            }
+        
+            // Copy IP header, GRE header, sequence number, ERSPAN header, and packet data into the new buffer
+            unsigned char *ptr = erspan_packet;
+            memcpy(ptr, &ip_header, sizeof(ip_header));
+            ptr += sizeof(ip_header);
+            memcpy(ptr, &gre, sizeof(gre));
+            ptr += sizeof(gre);
+            uint32_t seq_num_network_order = htonl(sequence_number++);
+            memcpy(ptr, &seq_num_network_order, sizeof(sequence_number));
+            ptr += sizeof(sequence_number);
+            memcpy(ptr, &erspan, sizeof(erspan));
+            ptr += sizeof(erspan);
+            memcpy(ptr, packet, header.caplen);
+        
+            // Send packet via raw socket
+            if (sendto(sockfd, erspan_packet, total_length, 0, (struct sockaddr *)&dest_addr, dest_addr_size) == -1) {
+                perror("sendto");
+            }
+        
+            free(erspan_packet); // Free allocated memory
+            printf("Sent ERSPAN packet with sequence number: %u\n", sequence_number - 1);
+        } else {
+            // TZSP Encapsulation
+
             // Create TZSP Header
             struct tzsp_header tzsp;
             tzsp.version = 1;          // TZSP Version 1
@@ -430,6 +580,7 @@ int main(int argc, char *argv[]) {
 
             free(tzsp_packet); // Free allocated memory
         }
+    }
 
     pcap_freecode(&fp);
     pcap_close(handle);

pcapmirror.8

@@ -24,6 +24,15 @@ Specify the destination host (required).
 .B \-p \fIport\fR
 Specify the destination port (default: 37008).
 .TP
+.B \-e
+Use ERSPAN encapsulation.
+.TP
+.B \-s \fIsource_ip\fR
+Specify the source IP address (required for ERSPAN).
+.TP
+.B \-S \fIsession_id\fR
+Specify the session ID (default: 42, must be between 0 and 1023)
+.TP
 .B \-4
 Force IPv4 host lookup.
 .TP

pcapmirror.spec

@@ -1,5 +1,5 @@
 Name:     pcapmirror
-Version:  0.5
+Version:  0.6
 Release:  %(perl -e 'print time()')%{?dist}
 Summary:  A simple packet capture mirror
 License:  BSD 3-Clause License
@@ -10,7 +10,7 @@ BuildRequires:   make
 BuildRequires:   libpcap-devel
 
 %description
-pcapmirror is a command-line tool for capturing and mirroring network traffic using TZSP encapsulation. It leverages the `libpcap` library for packet capture and supports BPF syntax for filtering traffic.
+pcapmirror is a command-line tool for capturing and mirroring network traffic using TZSP or ERSPAN encapsulation. It leverages the `libpcap` library for packet capture and supports BPF syntax for filtering traffic.
 
 %build
 %make_build
@@ -26,7 +26,11 @@ pcapmirror is a command-line tool for capturing and mirroring network traffic us
 
 
 %changelog
-* Sat Mar 29 2025 Matthias Cramer <cramer@freesone.net> 0.5-1
+* Sun Apr 20 2025 Matthias Cramer <cramer@freestone.net> 0.6-1
+- Erspan Encapsulation support
+- added option -e to set the encapsulation type
+- added option -S to set ERSPAN session id
+* Sat Mar 29 2025 Matthias Cramer <cramer@freestone.net> 0.5-1
 - new option -c to count matching packets (overrides verbose mode)
 - reworked packet decoder to also decode arp, vlan and qinq packets
 - well known protocols numbers are now decoded